AKTUALITY - International Atomic Energy Agency

I N l S - m f - - 1 i 3 5 ?

AKTUALITYZ KLINICKEJ ONKOLOGIE

14

THE //. SYMPOSIUM OF RADIOLOGICAL PHYSICISTS

II. SYMPOZIUM RADIOLOGICKYCH FYZIKOV

< • ' „ • = ! '

Bratislava, august 1987

A K T U A L i t i

I L I I I C K U ORK

Vydár* tfatay kllnlok«J onkoltgl* T•lea Ú'*«1OTÚ pubilMolu

pr« p«tr»lra

Bmtla lara , auguat 1987

A K T U A L I T Y Z R L I S I C K E J O N K O L Ó G I E

Hls-rojí rpdaktor: MUDr. Přter Čepí tle, CSe.Záotupca h lavního rvd&ktorat MUDr. Andr«J ŠtatakRedakčné rada: MUDr. Pater 3ep<5»k, 0,50., liUDr. RHDr. J o c a f H»Ilr»,

d » o . HUPr. Ir«n Utftks, CSo. , MUDr. Andra]Hedakelat KUCr. R.TDr. J o s « f Halíc*, FhSr. J ú l i u e S t r l n k a , CSo.

Informaci.* pra autorov:Í r:spev!cj sa zssielajú v 1 «x«tnplárooh na adraaui

tístav klinlckej onkológl*(reáaksia Aktualit)Heydukova 10812 50 Bratlalara

Optimálny rcesah étiídií J« 10-15 ntrán, apráv > 5 atrán, per»oníllí 1-?strany, reoaasií 1-5 «tráa (1 strana • 30 riadkor, 1 rladak • 60 typ«r).

Vríepavkj posudzujti % r»o»nE»nti a iob uvarajnanl* aobvaluja radakSnárada.

rjzári«rka 16. Šiml* ju 31.II1.19B8.Pri c ltaei l e Aktualit r kllnioktj onkvlógl* aa pautíra akratkaozikol.

'/a,

THE //. SYMPOSIUM OF RADIOLOGICAL PHYSICISTS

WITH INTERNATIONAL PARTICIPATION

(Smolenice, 22.-25.9.1986)

II. SYMPÓZIUM KLINICKÝCH RÁDIOFYZIKOV

S MEDZINÁRODNOU ÚČASfOU

(Smolenice, 22.- 25.9.1986)

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r e k n e h r a n é p r a c - ' V : ; í >•. n v n R O J 1 " • .• ~ 1 ; 1 i p l •>>

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y e d » O K . ý i | i O « K r n t i i r o n ) b . l a H U r . . ' . ' j j r f i í w v i i , C . i o .

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t u 4 . ) r e f e r ř S ť v p r e d r l p s l l 6 p r » f i i ' . ' i : " k , ' 1 ? . < - v i a r a k o p n l n v i ' - i .

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p Ó 7 . i * ; • . - - f ••: I i f t r - n z V p i v . " . ' H r í t á i . i * . < ť c n v p r o g r a m b n ) r n z - i o l ř n . v >'- •• k ™ -

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e h . l a ů j i i i . ^ s p r f f i . - . e u l a a n a t o n i i c K ; . : ' s ! i i ' i r l a d " V p u t ri>lin;i ;oli ; vm r l n r v v u s i IJ i l n > j ,

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b u d e p r i r : O B o m i d o p l á n o v a n i a l i e č b j . I ? i K . M a c h a i n K . r f - t i n » í ' i l z RTO K!í v V l 7 . n l

o b o . T i . i í i n l l l ú i ' a » t n í k o v a p r e g r a m o B p r » r á d l o l « r a p e u < . l o i c f 5 p l ň r o r a n i * a n m o d * ] «

t u i k o v ^ h o z v S z l c u p ř i p l á n o v a n í ,

lmihý tematický c«lolr bol vanoTaný oelolcožnsj •lektronónovsj terapii a otvo-r l l ho nvojou prednéňkou prof««or KarEnark z U3A. Otázkám kor«kČ!-.;vch faktoroT1 oř,icac•';,••• li komor a křivkám build up bola Yenoraná pr»*n«ňlc« lng."ovdín a lag.Kovotnéna z ÓDZ ČSAV v Prah*. 0 do nim* t r i i ťaíkýoh íaat ío hovořil i'r..Jasa«ní hánnka a o ieodózovyob křivkách při "Rnou»»" Dř.Fsnohřv z Bulharska.

- 4 -

; r u f o p n r Aalp'ora zo i v í ri i k M i t v o r i l '.re t i blok ^ " ' ' i . i í ^ i " r o ' ' t o ' "v> c. o y ? t ^ -me CAHT vyvlnutom v a e v e r s k ý o h «ri . ' , ln '(ch a o "skúfl»iu ^ • i ><ch o Vlnr ' T " n n n . "••ÍB-t u p c v i R n5 o». tur;. <*h f l r i o m - Voo^t n íuynt - o'••7.r;-'m111 ú<" RB tr.i'kov H ; T P > ' ! I n r.a~vým vvrubnjm prci'.iram 'in cipi : i t rve j [ T Í f t r o . i o v p J \nn i:p.i ky ::ati\"ris-^J r.r r ' " ' : " V r«;>lu.i r . O o r u u k o v s I r .I .J In/com zo ^':ii( oa z a i n p r a l l nu v - ť i:«vj t<T»pí ' . j . !::»•.'• • ' ' n va Itn'..Kovflř r o f e r o v a l i o fyz ikó lnyn ! i s a p n u t o c h " q i i ' M t y a « i u r e r ^ » " <\ r.'/»»'?: CVÍÍB kolek t ívom o k n l l b r ^ c l l lonlzn^n.vch komor a i. por"V!,Ovacích u p r a t l«i"k. ! rpsr. tw-ťou v b r a c h y t e r a p l l sa i a c b q r P l R I r.Síymcr.vk z r o T s k n .

V bloicu otázok tyicRjúoich sa ochrany <pr«C r laron ín ' r e f e r o v e l I r . ' i n h a ro mertuií apHtního rozpty lu a I n g . r » r n i ř í a z !Í1 Z f. AV T r-7>ih« na znot-i-nl r*spelctromotriíi X - í l a r « n i a o « n « r g l l 10 - 3>'O keV. I r . i omhnzlcy z V.iAl !n--.-or11 ov l s l O B t l e f e k t í v n e h o l ln«árn«ho sbaorbčního ko»fi '-ier f n.

TOHIKIII^ blolc tylcajúol aa biol.iKlox.vol) ntrfzok ^ivc^rl] pmr»«nr Vurtin 7 V«;k<>J i i r l t í ín l* pr«dnAĚkou v«novtvnou prt í ívru i lu p>> o i f f l i m i i . kumulnt; VM>O i n i r *rór.nyoh frakclonnííných noh^m h o v o ř i l lnf;»I'rnk«B 1 KN •/ i rnh» a p"slt-''!uka Ir.i 'andoveJ a k o l e k t i v u z Oulhftroka bola aanmriníi n« o ' ! n r « l « "'< •:>

gu.Fo v a ř ň l n e prednáňolc bola bohatá dlsicuBla, ktor-í ns nr:o/i. xrát pr»r.l».«O» r pr»d-

náéKOveJ m i e s t n o a t i 1 <ío npolorenakyoh pri»i<torov zámku.Súóneťou nympozia bola I výstqvka nlPrrtorýoh pr ía t r» lov fy Th»r«"' no 1 T.'ucle—

tron.Celkové možno Konétntovaf, íe aympózlum málo velmi dobrii odbornú úrovaň, ako

to v z/lverečnom hodnotení ivvedal í prcf«»or W«iotaai zo ,*!v ;dak«. '•brr.r.řunl 1 i em»aa navaájom a novými poznatkami z daného odboru vo sv«t» a prezentovali sae aú-čaaný aiav rádloleglokej fysiky u nia. Nadvlasall aa nov ; x 1,takty, ktor^ urřlt*budu prínoaom do áalěej práoe. l í íaatnícl •• obosnáalll a pKkri in prcntra^ím .'r,c-lenlokóh .• zámku, kúpelml FlaSťtuiy • to «1 oren»tou pohostlnnonťou.

Sympóziu pradohádsalo »a»«<3anl« £7011? r Bratlalara, na ktorm sa / .úfastnlli

záatupoovla IS Sl«nalc/oh organizáolí . Bol svolaný nory T^bor VT.WT na ř«l« aproftaorom Leet«o« % NSR.

Na role 1991 a* plánuj* I I I . sy&pósliw opMť • medslnárodnou úřanťou podtou EPOMP.

RSDr.Vlara La«ii,oYá, CSc.

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THE II.SYMPOSIUM OF RADIOLOQICAIi PHTSICISTSWITH IHTERMATIOHAL rARTICIFATIOK

(Smolenioe, ?.2. - 25.9.19«6)

Cllnioal radlophvslcs haa become en Inseparable part of the '-ruieer th»r«pyprooesa, elnce It help* lo Improve tumour loca l i za t ion , •courncy *nd optimizationof irradiation plans, verl f loatlon doolmotry in vivo, and - last but not least -protection of tho staff arid th« pntiente opainct iijideslr&Me Irradiation ooiaequen-oea. In ordor to exchange "Xjmrlenoe and to anttr into relations with aptciillatafrom foreiKi) countries the Klrat oympoalum of Hadlologloal <'hynlcinta with Inter-nal lonaj participation waa orKanited In Uratlalava In l''Ul. Aa thin me»tinf. was anunJlnputable nurcaaa, the Cr.»choi.lovak lladloal .'.oolety of J. l,.i urkjne -u.d the In-ntltuta of Cllnloal fiioology in Bratislava oonvoned the I I . Symposium of Hatilolo-Sioal Phyalolnta with International part ic ipat ion, which took plaoa in the Honeof Scientiota of the Slovak .Jcience Academy in Smolenloe in "eptember l'-fft. Thei"ympoBlum was apenoorad by ttio »'LMJ' (European Federation of rginizatl^na forModloal rhj-nloa) ftJid l ta hcinourable ohalrman waa profeanor .1 ..'i.i'll rton fmn JraatBritain, the f l re t oiiaj rman arid oo-founder of the KFoMP. At thia opportunity hewaa gnuited <->• madnl of honour of the .Slovak Medioal Soolety by asalatant pro-fenaor Ivan Knuica, V..1'.

The ac ient i f lo aacretary of the Symposium waa Viora Laglnov/i, i .:"o.At the Sympoaliun there were 88 participants from 16 countrlea, n<>t or.ly from

Europe, but also from beyond the aee, - from U.'i.A., India and -ir«nt Britain. Mtof \7 for<tij(n partioliifinte 26 hud givnn a l»oturo< i . e . of the total n ;mb»r nfrcportu 11) thay had more th«n a half.

AftiT th* addraaa of weloone and oonuni>n »raent th« hor.oura.bla ohalrman : " o f « -sor Clifton from i.reat Britain made an lntroduotary apeeoh. The «ol«nt l f ]r jfh»-dul" waa >Uvlded Into 'j units:

I. Therapy planning^. . .'llnloal doalraetryjl. "he Inatrumeii tal technology teclinlquos and "quality aasuranc'e" In rndlothe-

rnpyj4. i(a<5i«tion protection probler.a in radiotherapy;5. iUol,,(5ioal problBma in radiotherapy.

The nrat unit of reporta waa daaltng with the role of computers in therapyplanning in view of aocuraoy of anatomlo data neoeeaary for th« therapy planninf,aa well ma In view to the >uttlraiia doaa dl«t rlbution.

Profaaaur Clifton lnfcmed the partioipanta (hia apaeoh la not Included Intothe mlsoellany) about the new method of 3-dlmenalonal reoonatruction, vhlch laused at present mainly In head and neok aurgary, but i t probably will impror* thetherapy planning «a wall. J.Uaoh, H.So. and J.PotmeSll, M.Sc. from the TeachingHospital, Flsafi, CisaohoalOTaJtla, reported about tha procraaai of radiotherapy plan-ning and tha model of panall beam In planning.

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Th« seoond unit was dealing with ollnloal doslaetry and m opened by the Ice-t u n of profactor Karraark from U.S.A. about th« total akin eleotron therapy.J.Kovaj, U.Sor and J.Hovotny", M.3o. of the Cseoh Solanoa Academy, Prague, apokaIn thalr lecture about oorraotlon faotorr of ionlzatlctn ohambara and build-up cur-ves . About doslmetry of heavy ohargad partlolae apoka doctor W.Hansssn from Dan-mark and about leodoaa In unit "Rocus" dootor Fenohav fro» Bulgaria.

Profaaaor Rune Walstaa from Sweden openad tba third unit of leoturee by a re-port about tha CART-oomputar system, developed In Scandinavian oountrlaa and aboutexparlanca with Mlorotron. Tha representatives of aoaa f l n u - Voogt and Guyot -Informed the partlolpanta about th« new produotlon program concerning top techno-logy In radiotherapy. V.S.Khoroahkov, M.D. and S.P.Llaoveta, U.V. froa tba U.S.3.R.gave a l«ctur» about dlffarant proton Irradiation ttohnlquae. J.N'ovotn.f, II.So. andZ.Kovir, y.So. reported about phyaioai aapaota of quality aasuranoe In radiationtherapy and Vlora Ltglnora' with her team reported about lonlzatlon ohanbar ca l i -bration and lnterooniparlaoa meaauramant. Mra.ScymoByk, M.D. froa Poland apotca•bout brtiohytherapy.

In th« unit dealing with radiation protection proMeut reported A.K.3lnha, M.D.from India about maaaurement of baokaoattered photon* and r.Pamlfka fro» tha In-stitute of Radiation Doslmetry at the Cteohojlorak Aoadeay of Sclecoe, Fragua.a poke about speotrometry of x-rays froa 10 - to 300 Ker, T.Porubsrky. I . e . , fromBudapest reported about the dependenoe of affaotlra linear attenuation coefficient.

Tha last unit oonoernlng blologloal problema waa opened by professor Mnrtlnfrom Treat Brltalnj he gave a laoture about surrlral after radiation. About theoumulatlve effeot In fraotlonatlon sohemas reported K.Prokei, H.So. froa theTeaching Hospital, Prague, and the last leoture of V.Pandora, H.I. and her tea*from Bulgaria was dealing with radiation treatment ot malignant na«opaaryng*altumours.

The majority of lectures was followed by a vivid dlsousslon, continuing nanytines also In the lounges of the castle.

An exposition of some apparatures of the flra Tharados and Hue la tr on was alsoa part of the Symposium.

In aJ.l, It can be stated that, the Symposium had a high professional standard,as was said In the olosing speeoh by professor Walstaa fro* Swedes. Tha partici-pants had Informed eaoh other about naw knowledges In their specialisation and tlMoaeohoslovak radlophysiolsts reported about the present state of radlophysice Intheir oountry. The partiolpants got acquainted with eaoh other, and these newcontacts surely will bring about Impulses to the work. Tha partlolpantc were a l -so shown the beautiful milieu of the oastla Smolsnlos, the Pleitany spa and theSlovak hospitality.

The Syaposiun was praoeded by a session of EPOHP In Bratislava, on whleh par-ticipated representatives from 18 Mabership organisation*. A new IPOUP oosjaltteewas eleoted with professor Lasts from the Oeraao federal Republic at the head.

The III . Symposlusi la to take plaw* In 1991, again with international partlol-Patlon.

Vlera laglnovtf, D.So.

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I . T R E A T M E N T P L A H H I K O

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A a r h u s K c m m u n e h n a f l t a l , Aar-hua, Denmark

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t '• i n M u a n r a t h a f". -ur.mt'frm. A | « r f e c t s ewn » r a o a e t r y i s o l t s j n a i i o n l y f ••< • r v j t n -

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thin ;nj.«>r hns bean to investigate by phiuitoa etudiee how auch darlatlona froajthii. Itfeal altuatlon induce ahlfta In CT-«uBbera for four CT-<yata«ai O117070, 8e-neral Klectrlo 8800, Phil ips Toaoaoaa 31C and Slaaann Soantoa fRH, and to relatethen* phantoa atudlae to actual o l l a l o a l luv*atl«atlon# and lntsrpretatlona ofabsolute CT-nunbere in <tc rta, l l r e r and spleen. The oonneqiiaT-eas for the uae ofCT-niunbers In CT-baaed dose planning praotioe haa also bean lnTeatlcmted for the?JH 17070 ar.i the Soaatoa L'RH ayeteaa. •

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t a s haa tha nao»«tri<- mv.i.mr-

treaant arhiaT»f1 ly vBrv i tv

1U> raapi'ct to tfi^ | » " n n i-rrmy nn

an'i rh^raby nijttat >h» »c«n fi"l<l to tha s i c * of tha patient . Th# O-ir-land more aimpla gacnetry 1« raprasantad by two CT-nystaaiii: the O.E.PPPO at"l •»•:iOUATOM ayatan.

A wstar a |uival«nt p irat ic ph"nto« h»s baan uaed with • iMaaetar of i?i an »n*with th« poBniMlity of plnclng up t» r in* anallar inaerta into tha phantoa « n haolutiona of diffarent danaitiea and 7. rrjuaa /Tip. 2/. Table 1 ahowa P solutionswith the ir phyalcal ânsit iaa, re la t ive elctron denaitiea to water and efract i»aatoaic nunbara. for comparison are ahown the corresponding raluaa for auacle amibone. To thla cylindrical- ehfaped phantoa perapax al iraa can be added to changetha rat io between tha twa axaa froa 1.0 to 1.56. For a aet of aeaeureaenta we pattha coherence between the CT-nuabera «nfl tha danoitlaa - t.ha aaaa danaitiea or the.re la t ive electron danait iea . /Tig. 3 / . For tha a>aas <*annitlea i» ia ponaible topresent thla coherence aa two etraight l inaa , one for soft tiaaue and one for bona

- e -

rig. 2 . 3

For eiaetron denaitita it i* a littla aore eooplax. In tha followit^; ww w H l ceo-

csntrat* on the <MM d#n<ity lin* for aoft tl«u#. * straight line ía aafÍ!*#ó by

two p*r*m*t*ra: ita alopa *nó < point on tha Una f. *z. for Penalty 1.0 /water/

and the CT-nuabar for water /C H.U./.

SOiuurJ.

. - ! •» * t,»}tt

put iri

I . . .-V

1

I

i »i

\~ :•, } ..-

: ... _!...._._ . 1 i JTable 1

In table 2 such a repreeentation of eoft tieeue linea are ehown for the four

CT-ayeteaa and for three different retioa for the two axea - froa the circular

ahapa to the aoat oral ehape. The bottea line ia for the oral shaped phantoa Ale-

placed to a aaxiaua to one eide in the aperture. *or the EM7O7O aystea we see a

change in slope when the a/b ratio lncreasea and we eee iiilte a rewritable ahift

in the water veluee indicating a bad calibration. Por O.K. 8800 we have parallel

linee and slaoat zero values for water tor cylindrical and aedexate oval shape.

Deviations sre ssen where we have aaterlal outside the scsn field. For the Soaa-

toa we eee parallel lines <«nd vary food water values end only tmr the eitreae Ala-

i' ".'•'!« 'VI j l i ' lM T MHufw CIU-

. . j

r"L. - J ; - r

_ . . JTable 2

plaead phentoa *• aeeeure d«-v la t lone . TMe ecenner type»:•• «n «p#rttjr» <Jisa»ter or 7©ea. For the Tcaoacan we againaaa changes in slope and In tbavaiar ralua 4ep*nding en be>wall tha phuntOB »<3juate th»•can f l a l d . Tha aaaa picturaia aaan for tha llnaa in thaton* region for ihaaa four aya-laaa.

• hat doaa a l l thla aaan to our c l in ica l atttdlaa?Up to about t>0 aubaaiuant patlant atutilea on aach CT-ayataa ).«r# baan «na9y-

tad by dataralnatlon of tha aaan CT-nuabara for an tr<-» in U.« aorta, tr.a ailaan*n<1 for thraa araaa In tha l i var . Tht acana hava br«t> parft i»*fl by typical cJlltil-cal aaehlna tachnljuaa. Tabla 3 ahoaa tha aaan *aluea of ttaaa C?-nuabara for tha

- .» • *:•• i... . . . eer.ter uraa in lha M»ar for tha

1 , four f l f farani ayataaa. Taa aaa-.' •• sl*'-' • » • . .. -•. « i «v.i ' bar of azasinatlona ara l latad

• • i i - i

'. , in tha f l r a t coluan and for aach

• ' ' j ' - ' " ' ! aear. valua tha atanderd devla-

• • t ion ia calculated and the me-

dian value <Vtarained indicat ing

a regular d i s t r ibut ion of CT-»a-

. • ) u t i . The ixnga froa lo«eat te

tii^haet rr-»alue for each eerlaa

of exaainatione are H a t e d . Scana

of the c ircular ptantr.a « i th the

aean par'<aatere uaad reaulta in a water value of 0 - 3 ti.U. The deviat ions for

M17O7C end TOMOSCAM auet therefore be aaalgned to devlxtlona of tha patienta froa

the ideel geoaetry.

I

Table 3

Ts!le 4

In table 4 we see the aean valuoe for all "> araaa in each aeriee of exaalnetlenaand their standard devietiona respectively. for the >J.E.8eC0 and SOBUTOH aye teawe aaa a vary good agreeaent for all five areaa and rtry unlfora veluea for thaaraaa lx .he l iver. For the MI7C7O we have another level aa shown on the previouselide aji* we heve higher values for tha peripheral areaa In the l iver due to thedishing effect **ich unfortunately never has been aolved for thie aystea. Aleo forthe TOaCCAN «e have a «t.ift in CT lsvel and fluctuations in the l iver.

VI IT I trj

- 10 -

The consequences on 3ese calculations using CT-niiabere Trom Cifferent scanner

ayelea* her* been inr <»«tie»t«(J by •canning pstlenta »iif carrinoae of the bl»<«aer

In two of the aoet different systsas: the MI7O7O en<! U.« 20KAT0M DJH.

A 3-field technique Is used in our c>pertaent «it» ml jvi<*uel Bhielfljr* tlocks

*ni coapenseting f i l ters for esch f ield. /Fig. *>/.

Dose cslculetlore for toth sete

of CT-d«te hove t>«en i«rforsaefl on

a KT'FlAji 31 /upgraded/ eystsa for

* ft>m pstipctn aa e j<ilot study

end «re et o«n jr. t tU« 5. The ee-

ae rar«a;»t»rB of the rafilction

fields f:e»i> ieen ua«1 for tt* two

ca) cu)»'.:' nn of tr<e rercenta^e sb-

aort«<i '1oe«e it: tte rentre joint.

The calculation* urinn CT-n«-Bbers

are bssed on U.e vuivelent r*thtO... . . . P^« uoo- «•» length actho'l.

The cslrulstions ^»lv• be«r, ncr-** salized to bulk or water *3uiva-

Itm tiasue for the SHI-4ftta. TheCT-aystsas h"ve been calibrated for different phentoa shapes and ayatea reraa*-tera /wedges/. For the IHI data we aee a shift of 1-? percentage depending on thacalibration used. We do not sse such s varistion for the SCHATOM systea. A varia-tion up to about ons percentage between the t*o nystras for bulk cslrulstione areobserved. The influence froa internal variations of CT-nunbera on tt.r flose calcu-lation on the whole can therefore be described ea no^est.

I ' i

Table 5

; . i < • • : < - . i o

i - - • • • ! r -

r ! JJO t I QQ ]

. . - -4

"* 4_T^!.9? i

OR 1

la oonoluslon It oaa ba stated that for quantitative use of CT-m*ibere tb* l o -cation and she pa of the patient in the aperture has to be taken into considera-tion and an optiaal ndjuataent of tha ecan field to the patient ia necessary. Fur-thermore there eaeaa to ba quite considerable variations between the differentCT-aystea* and therefor* i t is very important to analyze the actual eyateei for i tssultebil ity for jusnlltetive CT which not necssssriljr is disclosed in th« tradi-tional parsastars for the plctur* quality as noise and spatial resolution.

Quantitative CT for diagnostic purpoaea is therefor* -jueetiorisble an* BUST ifn**d*d always be done under vary controlled conditions but fortunately i t is leascrit ical for dose calculation purpose*.

- 11 -

CT-BASP TKIATMPIT PIAMHIKO SYSTMFOB COMMODOKI-64 HOMl-COMPUTgR

T. Treer,

Department of Radiology,Medical Urivera i ty P i c e , Hungary

In Hungary we have a p o s s i b i l i t y to use a treatment planning program on a cen-t r a l computer ir Budapest. At the Medical Univers i ty of Pecs we a l s o have « t e r -minal to t h i s computer but the qua l i ty of data l i n e 1* continoualy rather bed. Sotwo yeare ago I decided to develope euch a program. We had money enough to purche-ae only a home-computer type Commodore-64.

When developing my eoftware I hud two a i g n i f i c a n t problems. At f i r s t , the oor*maaory a f t e r loading the b'UPBRORAPHXC system Is only 3? kbytes; at second, thespeed of C-64 i s rather amxll . Ho I ueed very simple approximation methods forcomputing the doae, in moet ceses l i n e a r in t erpo la t iona ; and to make the programf a s t e r I used a s p e c i a l polar coordinate syetem for def in ing the grid p o i n t s .

The main advsntage of t h i s system i s that i t can compute and draw the ieodoeecurves in one section of the patient irrsdiated by static fields of cobblt-60 u-nit for much lower price then the other more complex doee planning systems.

Ir. the evaluation method corrections are made for the shape of the pstient'scontour, for wedged fi lters end for inhomogeneities /lungs or bonss/. It is po-ssible to view two alternative dose distributions on the screen in one second.It helps to chooee the optimal doee plan from the alternative dose distributionsby not only computing the volume dose absorbed in the tumor and the healthy t i -ssues, but evaluating also the effective volume rioee /EVD/ introduced by Wendl.au-sen. By the uss of EVD numbers one can find the dose plen which gives the smallestradiobiological risk for the healthy tiseuee of the patients. The depth doee iscomputed by linear interpolation between the data from Brit. J. of Radiology,Supplement no. 11.

425

I

T *

t

t

Flg. 2

The f i r a t al ide shows the half of a dose-profi le of our Co-60 uni t . The causeof this small decrease in the middle ia that in this old Hungarian unit /type Qra-v i c e r t / the f ie ld- l ightening lamp la situated in the middle of the gamma pathway.From profi le measurements at 4 different depths I constructed the decrement l ines/ F i g . 2 / which intersect the middle l ine at different diatance frou the aurfaceof the water phantom. So a l l decrement l ine s are characterized by two numbers ina f i l e of the program. Profile dose i s computed by interpolation and i terat ion .

- 12 -

I l l t t t l I 1 I tj

$

•4-

•v •. -'• •

. 4

Ne«'. - : ; "a a!.owa /F ig . i/ trifl computed iaodoee d is tr ibut ion of an open f i e l d .i>i. :l.e r.eit sjifle /F ig . 4 / we can • •« e do«« plan in M sect ion of a patient

I.BV n.f- « u.mcr ir. tr» parot ie . Two wedded f i e lde of 6 x 6 i r t uead in the d i r e e -t ii<r . •' <• d e c r e e s .

:).t . xjutir .^ t ine i» cca 4 minute* per f i e l d .*t\ai sLcut the accuracy of t h i a prograu? Tw» waeka a^o we i r r a d i a t e d a few

o s c U i I.J ••'.' Aliet-HL' hbnrio phantoa and aensured th» abeorbed doaa with 420 TL 4 e -t e c t u r n . i t f rt-oul t s uf t h i s meaaurejiente have shown that the avail BUB d i f f a r e n c ate twee : t).e place of c<m;uted and Measured isodoaa p o i n t s i s J ma In thr c«ee ofa dose p]sr. of f jur r ia l ."a .

To suo.mnrize my i" t* i 1 think that t h i e program f o r i t a i n e i p e n e W e C-6< lauaable for a t a l i c rielrl l o s e p lanning .

TCIOHEIHX AND DOSt FLANNIHGIN TbLEOAIOtATHERAPI

CF THE PBOSTATIC CAhCIHOMA

V. Uiltr^.ev, L. Alexandrora, II. Houahaov,t>ncolorical !<eaeiirch I n s t i t u t e ,

A considerable increfcse of the proatatic earcinoa* incidence ia observed Inour country as * e l l aa in the othera in the recant years. There war* 447 new ea-aea in 1970 and they had riaen to 638 er to 14,3 par 100 000 aala population In19t'-y /*>/, VY.e proportion of patianta indicated for radical proetatecto«y ia varyansl l •":, - 1^*/, so the majority of pat ients , even without eridence for general i -zatior. of the tumor procsas has been put to pa l l ia t ive treatment - cheno- or hor-aotinl it.ern py /2/ .

ThP introduction of high energy treatment units which enabled delivering can-cericide doae in deep situated tumore and sparing the organs at r isk, as wall astt.e c^si.^ei attitude towards the radioreaistance of the prost«tic carcinoma, havereined the iroblem of i t s radical radiotherapy for patianta with local or l o c a l -regional exu-i i / s tages 1 - I I I / , ouch are about 1/3 of the newly diagnoaed cases ,

- 13 -

oorreapondlng la Bulgaria, to roughly 200 person* par yeajr /5/. In some foreign ra.-

dloJLogloal oenters iwdleal radiotherapy la already oarrled out and high aurrlTal

ratae ara reported - 55 to 85% <31e«aae free fira yearo aurrlTal rate for tha stt>-

ga mentioned abore /I, 2/.

When radical radiotherapy is performed tha target volume conelats at first, of

a small target volume comprising the priasry tumor where a total tumor doaa of 70

Oy is to be reached, and, at second, a large volume including tha primary tumor

and the p]vic lymph nodea in which we usually give a total dose of 50 Qy /5/.

In determining the aaall volume it is taken into account that the anatomical cen-

ter of the proetete liea on the central frontal plane 6 en cranially from the pe-

rineum /Fig. 1/. In caudal direction it reaches tuber ossia ischii and ita exact

Bite depends on the spread of the proceas. It could be determined by « simulotor

after Bagshaw's technique /I/, by

ultraeonography /4/ or computer to-

mography, and usually ha« spheri-

cal form with a diameter 7 - 1 0 cm.

The large voluae includea the re-

gional lymph nodes as well, i.e.

all the true pelvis, ao that in

cranial direction it reaches the

promontory, in caudal direction -

tuber oseie iachii, laterally -

Kg. 1Sagittal and frontal eoheme of tha anato-mloe.1 struoturea and tha target volume

1 cm outside the terminal line,

ventrally - 2 - i cm in front of

the promontory, and <1oroally incor-

porates the frontal 1/3 of the lumen of the rectum. Taking into account these re-

quirements, an anatomical cross-section is drawn up individually for every patient,

Th& radiotherapy is performed by a teletherapy unit "Oammatron - 3" with ro-

btilt-60 gamma-raya. Dose planning ia doaa by computer program ICENDCSA /j/. Be-

sides the main transversal plane, a series of parallel planes &re assigned to en-

sure the adequacy of dose over the total treatment volume. In order to consider

the effect of tissue inhemogeneitlea on the dose distribution the contours of bo-

nes were given using CT ecana. After investigation of the methods of telegamrae-

therapy of the primary tumor the leocentric pendulum irradiation was found to be

the most suitable /Fip. 2/. It provides homogeneous dose distribution in the tar-

get volume, and a considerable fall of the dose in the organs at risk - rectum

and bladder. Optimal doaa distribution ia achieved by the arc of rotation frna

•?40° up to 100°; the rield alt* being from 7 cm up to 10 cm. T»m situation or (he

isorenter is chosen individually for every patient according to his "netnmiua]

characteristics and spread of the tumor proceas. The dorsal wall of the rectum and

the ventral part of the bladder obtain 50 - 80% end the neck of the femur - t«3ow

50* of the tumor dose.

We have chosen the box tachnique for irredihtion of the large target volume,

applying fixed SSD b*ams.

The complete planning and irradiation techniques have been checked up on nn

anthropomorphic phantom "Alderson" previous to start treating patients. Topogra-

phic cross-sections have been drawn in tha transversal plane through tha center

of the small volume, assumed to be a sphere with a diameter of 6 cm, and in four

additional transversal planea at diatances 2.5 and 5 cm from tha caatral plane.

It waa estimated that tha optimal dose distribution can be achieved by a rotatio-

nal arc of 240* and field si«e 7 cm. Tha phantom was irradiated under theaa con-

ditions and doae values In points lying on the five plansa ware measured by tner-

meluminescent doaemeters. Tha measured valuea ware compared with the planned va-

- 14 -

lues. The diff*r*nc*e did rot p*c*ed 5* inaid* the targat volu»* in th* centra:plans and 10*. for a few points outaide thi* volum* /Pig. 3 / . In th* additionalplan** larger difference! were found but aoet of th*m were s t i l l within the l i -mit* of - IP* and only in a few point* in the p»nu»br»l region they reached 20*.

Dose distributionfrs« 300° pendu-lom irradiationof th* n i l tar-get

In • similar way th* accuracy of irradiating th* large volume was estimated.It was proved that the deviations of th* measured doae fron th* planned floe* didnot exceed 5% in th* central plane and remained lea* than 10% in the other pi fines.

Fi«. 3Doae distrioutionfrom 2*0° pendu-lum irradint ionof the smaM tar-get voluar in aphantoa. The rum-bars in circles arethe percentage -1 if-ference* betweenmeasured an<i planned

values

Thia technicyue has been introduced recently into the clinical routine of th*Oncological Research Institute in Sofia. The anatomic-topographical planning iaperformed by a simulator and information for the location of soft tissue organais tricen from CT scans. Computer supported three-dimensional do** planning in ful-f i l led for every pati*nt. During th* irradiation the delivered dose in the organsat risk is checked up by in vivo oeaauremente with thermoluminiecent •ios*uet.*r*.For measuring th* dose in the rectum • plastic cathet*r ia us*d, in which capsu-l*s with lithium fluorid* a* pa rated by radioop*i>J* murk* re »r* plrced. In th*urethra there is a thin tub* with lithium fuorid* rods driven in, so that the rod aare inside the small volua*. Th* exact poeitiona of the doa*met*r* ar* defined by

- 1 5 -

by ň"""*a*!*adioyraphy, performed itrtnediately after irrarliation.lt waa found that

the uiřaKurer! vsítila differ from th« t-lanned onřa by not more than 5t in the re-

gion of platau an^ léna th*n 10% in the per.uibra.

The invfati^wte-i írradiaHon technique en'blea ta mak* ar. adequate doae dietri-

hutirin for radical radiothetnpy of the proatatic carcinoma for patient* in local

anři itx-xl-rapional ateêa. Th* irradf-tion ia eaeily performed and the accuracy

of th* rinwo îatribusinrm c^rreaponde to the demanda in ra<!ioth^rtpy.

i'*fer<-ncea :

1. bagahaw, M.A.; Extended radiation therapy of concer of the proatate. In:

Cancer /Jupfl./^, :96O, 9I?-1921.

2. dei Hega'-. J.A.: Lon^ tena curative reaulte of radiotheraRy of patienta

with inoperable rroetatic cf.rcinoaa. In: Radiology 131. 1979, 291-297.

3. Konatantinov, B. et al. A prograa for computing doae diatribntiona in iao-

centric te)eâmmatherapy. Proc. Ill Mat. Conf. Bioajed. Phya. and Ing., Sofia,

I960, 38 /in b<;lK./.

4. !ee, D.J.: Carcinoma of the prottat*. In: Cancer j^, 19B0, 724-727.

5. Mouahmov, M., Fantchev, p., Alexandrova, L. and MMtehM, V.t

py of th* prc'ata with local and loca!-re%!eml tpreadinjř. In: Oneolagija

1985, 4. P O ] - ^ /it. bulg./.

COMPUTE? H O I RAM

FOP H!YJI1AI. AND PADI0PI0L0GICA1, CALCU1-ATICNS

OF THE rn-. TMET-'T ři ANS

IN LTMil.q HAU10Ti!hf./PY Or CARCINOMAS

OF HiE UTÍMNE CE!YIX

P. Matula, E. FutdA, J. Hexovd, M. Britnškovî,

M. Klvaňa, A. Katar

Complex radiHtion therapy of carcinomas of tr,e uterine cervix and enrSomatrium,

in which intr*c"vitary therapy playa an important role, h"a been e c r.cern rf

radiotherapiata and ^yneacolOřiate for long yeara. Tie rontrit-ntior, of pt.val

in ths team work waa limited to checking dosimetric parameters of radiraoiv*

eourcea. The pl"nniny procedure conwieted in the applicMtion <f et'nderd !*tlea

and achamea elaborated for specific confiûrationa of intracavitory ar.tjťcea and

atandar treatment techniquea for external radiatian be^na.

Theae achemaa do not ta)ce into account marked diffarencea in doae Matriřu-

tion cauaed by pathologic devietione of tho uterua and by other chrnêa.

By adopting the aftarloading technique and uainx computere preconditiona for

the tore conapicuoua role of the phyaiciat in the planning procedur* were piven.

The ain) of our contribution ia to give a aurvey of apprcchea to theae iuea-

tiona in our Department. One part of thia contribution deala with the analyaia

of the open queation - 'efficiency and information value of phyaieal veraua ra-

diobiologieal plana in the complex radiation therapy, in the complex radiation

therapy, in the view of the praaent knowledge concerning doaage equivalenta*.

For the time being we apply the endocurietherapy by a manual afterloeding

- 16 -

technique with makeshift applicator "FIMAL" loaded with 226Ra /3/.

The localization of radioactive sources i3 determined by ne&r.s of s stereome-

tric method with the calibration of recording obtained on e single X-ray film /5/.

-The calculation of the isodose plans is perform** on the treatment planning

system OSS Philips installated in our Department in KoSice 1 1/2 year ago. Since

the software of OSS Philips does not allow to use input date from e stereometric

record, we developed a small program "ORTO" to transform stereo-dats into ortho-

gonal coordinates using "Free programming mode" and both graphic input and out-

put devices of the computer. An example of the output from the program ORTO is

demonstrated on the Fig. 1. It serves as input into the program BRACEY Philips.

Pig. 1 Pig. 2

An example of the output from The output of the program BRACHY

the program ORTO

The output of the program BRACHY is on the Pig. 2.

The calculation of the isodose plans for the complementary external beam tech-

nique /split method/cen be performed on the basis of CT - cuts by the program EX-

TERNAL with the possibility of a 3-dimensional dose distribution reconstruction.

The computer system OSS Philips does not allow as well to calculate composite

dose distribution from the external beam and the lntracavitary therapy. This is

a serious limitation in complex planning process, especially in this anatomical

area.

Therefore we developed a new computer program "SUMA" which summarizes Indivi-

dual contributions from endo- and extarnal beam therapy into one output isodoae

plan /4/. The program was elaborated for the computer SM-4-20 made in SSSR, but

Is adaptable to various oomputer systems. At present time it works la 12 radio-

therapy departments in <5SSR.

To support the treatment planning we have set up a terminal in our department

connected through a telephone network with a central computer in the distance of

6 km.

The significance of the program "SUMMA" will be illustrated by a rather ex-

treme case.

We found on the stereo-recorded X-ray film of on* patient /female/ a narked

deviation of one intrauterine applicator which was 16 mm from the midllne In the

- 17 -

plane of the points A and B /Fig. 3/. The consequence of this deviation was re-flected by a different dose in the points B /on the left pcint B +56% and on theright point -45% versus standard symterioal dose distribution/.

Ii

Fig. 3The output of the program ECT-3Dillustrating the asymetrical dosedistribution in the consequence ofthe deviation of uterus

Pig. 4The oomposite isodose chart for 2 Ra-insertions and split technique with thecompensation by the moving beam fieldto the right parametrium

The oomposite isodose distribution for two Ra-Insertions /60 Gy/point A and36 Gy/point B external beem therapy given by the standard split method/ demonstra-tes an underdosing in the point B. This underdosing of the right parametrium re-sulted in the persistence of the tumor. We therefore supplemented the dose to theright parametrium by an external moving beam field /6 x 10 cm / as can be seen onthe Fig. 4. The oomposite isodose plan shows the result of this compensation -both sides were given equal dose /80 %" isodose/.

An analysis of Ra-lnsertions pn the basis of X-ray stereorecordings and sub-sequent calculations showed that we had to give such compensations in unsuitabledose distributions In 12-15& ot patients.

The oomposite isodose plan appears as a convenient aid for the elaboration ofthe optimal treatment approaoh.

We are aware that a physical isodose plan does not reflect in full extent ra-diobiologloal relations and effeots in the treatment volume. We therefore attemp-ted to analyse these effects by means of the so called "isoret plans". We publishedthis oonoept for external beam therapy in 1974 /4/. At present we are developingthe ooncept of "isoret plans" for endocurletherapy.

We used the results of the work of Ellis and Sorrensson /I/ which deals withthe relationship of the "dose-factor" on the dose rate in the low-dose rate region10-150 oGy/hour.

Calculation of the "Isoret plans" for Ra-lnsertlons was performed aocordlng tothe relationship stated In the paper of Gottein in 1976 /2/.

As the differences are not expressive enough on the output of "isoret plans"versus "isodose plans" we prepared the profile of the distributions in a selectedtransversal plane.

Fig. 5 demonstrates the differences between the physioal and biological effectsafter the composition of contributions from intraoavitary and external Irradiation*

The difference 1B 7,6%".

- 18 -

Our conclusions may be summarized Into

3 points:

1. Necessity of individualized planning

in radiotherapy of the uterine malignancies

using 3-D distribution calculations;

2. insufficiency of dose planning with-

out calculation of composite isodose plans

from endo- and external team therapy;

3. possibility of a deeper insight into

radioblological effects of radiation the-

rapy by using the isoeffect distribution

calculations.

Fig. 5

The plot demonstrating the differen-

ced between the physical and biolo-

gioal effects after the composition

of contributions from intracavitary

and external irradiation.

REFERENCES

1. Ellis, F., Sorensen, A.: A method of estimating biological effect of com-

bined lntracavitary low dose rate radiation with external radiation In carcino-

ma of the cervix uteri. Radiology 110: 661-686, March 1974.

2. Goltein, 14.: Review of parameters characterizing response of normal connec-

tive tissue to radiation. Clln.Radlol. /1976/ 27, 389-404.

3. Kazix, A., Matula, P., Kunstadt, E.: Fixed manual afterloading system.

5sl.Radlol., 38, 1, 1984, 61-65.

4. Matula, P., fdvana, H., Kunstadt, K., Put^S, E.i Contribution of "isoret

plans" to optimization of the dose distribution in the radiation therapy. Radlo-

blol.Radiother., 15, 1974, 369.

5. Matula, P., Putis, E., Kunstadt, E., Klvafia, U., Rexovi, J.: Construction

of the isodooe plans In radiotherapy of carcinoma cervix uterine using the ooa-

puter. I.Application of the stereometrioal method In tepometry of lntraoavltary

radiation sources. Cal.Radiol., 35, 6, 1981, 415-422.

- 1 9 -

TEL TUŽKOVÝCH 3VAZK?PRO Pl/NOVJÍNÍ I^ČBY ZÍňENŮí

Jiří Mach, Jaroalav Potměšil,Radioterapeutioká odděleni FH-Kl)!!Z, Plzeň,Výpočetní atředlako O3LOZ-K!)HZ, Plzeň

Úvod

Pro potřeby plánování láíby zářenia byla vytvořena oelá řada eaplrlokýoh nate-matiokýoh modelů, která popisuji rozloteni dávek v těle ptolent* (7, P, 9). Nevý-hody téohto modeld jeou zejatáne, velký ob jen experiHentálníoh údtjú, aalá flexibi-lit* pro apeoiální teohniky ozářeni (tvarovaná pole, ttngenolálni ozářeni) a těí-ko odhadnutelná ohyba při použiti s* jinýoh pvdminek, neí sa kterýoh byly odvozenyTyto nedoat*tky odetreAuji aemiempirloká oodely. Pro radloterapii ee zdá být nej-vhodnějáim model tuíkovýoh ave.skú.

Fyzikální model

Poloempirioký model tuikovýoh avenM vyoháti z lineámoetl BoltHaanovy tra**-portní rovnloe.

.{(?-,T,JT) S(?,T,R)+JdT"j<Ur./*;%(T*T",ň")())

T diferenolálni fluenoe SáatloS diferenoiálni huatota zdroje XáatioM- lineární aoučinitel zealabeni<í. diferenciální součinitel zeslabení pro InterakciT kinetioká energiejH jednotkový vektor smíru?* polehový vektorV diferenoiálni HaalltonAv operátor

Linearita transportní rovnice dovoluje rozložit rovnoběžný svazek, který kol-Mo dopadá na polonekonečná prostředí, na lnflMitlzimálni tuiková svaaky. Dávkuv danám bodu P spočtené jako integrál přispěvM od tutkovýoh svazků. Integrujese přes všechny tučkova svazky, která tvoří makroskopický svazek (viz. obr.3. i).

Obr. !. 1

- 20 -

Cal/ problem, JaJc aa'taMtloky r j j i d r l t drfrku r daain bodu, aa radukuja nai f jlc*ni E^rlsloati dirlcy T hlouboa h a ra rsdtflanoatl r od tuCkorlho arasku. Funk-ol PBD(r, h) dafinujama JaJco dirku od tuEkortfbo armafcu r bodu P, kdri enargla pro-i l * tutkor^D arackam Ja 1 J.

PBD(r.h) =

d (r, h) dirk* T bodu P

7 fluenoa narfla

dS plooha tulkorlho avazku

Mvku r bodu P od nakroakoplcklbo araaku apoitaaa podia ntfaladujfofbo rsta»

hu.

0(P) = (F(x,y).PBD(r,h).dS '

fuqkot PBD(r. h) pro fotonoTa"

U fotonoviho tArtrii zatfm n«bjlo popaano da'vkora' roaloiaof r okclf tuikov4bo

aratku. Itumi *• proto ryjit c axparlaantrflaa naaafanôb udajfl. UrSani funkoa PIS

ryohdti s poatupu publikovemâ v [\].

Proaantualnl hloubkovtf dtfvka TV Ja darinorina poaaraa dir«k r danrfs bodu a T

blouboa ionliaSnfho maziaa n* o^ntrilnim papraku. Podia ttto daflnloa a

(3) pfi S8D—>#• doatir<m«

l F n . f ( x , \ ) . ! 1 H f » ( r , h ) . d SPD(P) r 1(1(1. J i

(F .f,(x,v).PBD(r,h K d S

f ( x , y ) r f 1 ( x , > ) . f 2 ( x , v ) (6)

J f ( « , % I . I « M i , | , i . d - . J j f , , % > . r R H ( r , h ) . d s

pun1) - iw._°, . _. ......!j f . f x ^ i i i ' i ' i i . i . i - . # - . J r , ( » , \ ) . i n i i ( r , h )J 1 m / 1 . . "

J r ( « ,\ i . r u n f t , i i > < i " - » E X J r ( > , > ) . r n i > ( r , h I . « I S

J f , ( « , % ) . P H I i f r . h l . i l ^ I I ] I , ( x ,\ i . r R l i ( r , h l . d s

Po Jednoduohôh uprartfob ioatiriu* retail ( 6 ) .

J a a t l l l a A 3 —> 0, p«k

J f ( x , y ) . P B D ( r , h ) . d S = f Cx , y ) . j PBI)(r ,h ) .dS ^ f ( x , y ) . D ( r , h >

V ( r , b) ja drfrk* r bodu P od m i k u o prflfaau A S ( r l a . obr. 5 . 2 « ) .

Oar. 5. 2k

- 21 -

Doaasanla (3) do (8 ) doatanaaa

f ( x p , y p ) . D ( R , h W H J Z f C x , v ) . D f r , h )

PD(P) = 100.D(R ,l

0r 8

TAR pro krubori pola o poloaaru R ja daflnorajao

TAR(R.h) =DS

( n )

D_(R,h) ja dfrke T hlouboa h na oaotrAlnla papraku kruhoT^ho pola o poleX, M ja dtfvka r ttela bodu va "rolatfa proatoru".

Podia obr.S. 2b • rstahu (11) doataaaaa

| ) f r ,h ) z DS.(TAR(R*AR,h) - TARfR.h ) ) .2-1 (U)2 *

\ \

Obr. « . 2b

Pa iprmri n(r,h) = ns.A TAR(r.h)

Goaacanfa (13) do (10) slakajia T

ku.

PD(P) = 100

{41)

Tatab pro prooantualni hloubkoTou dtfr-

)+E If(x,\ ).&TAK(r,h I

TAIKH ,h )+ Z £ri(x,.v).ATAH(i ,h

runkoa f (z , 7) naji poplauja ralatlimi roalolanl fiuanoa »n«r«la • rovtna kol-a< k oaa aTaaku. Podia (6) Jaaa TjJidrlH tuto funkol Jako aouiis funkoi f j d . y )• f 2 (x ,y) . f j popiauja ralatlrnl roslolaai nuanaa aaargla baa pfitoanoeti kH-no-rfch filtrtt, koapanaafinloh flltrA'a tvarofaalob blokft. f£ popiauja abaorpCnlJainJcy klinorfoh flltrtt, koapass«Saieh filtrfl a tvaroTaefah blokfl.

Prl konafin^oh hodnotioh BSD Ja nuta4 Ta TBtaJiu (14) proT<et korakal c« dlT«t>-S«nal arasku a 6byt«k fiuanoa aaargla a roatoual v«d<l«no«*l od adroja. Ha obr.6.3 ja snaaorxMa* altoaaa prl konaBatf rsd^lanoatl mdroj-povreh.

- 22 -

Obr. 8. 3

Pa doaaaani prialufatfoh korakof do Txtahu (14) doatanaaai

1SSD • h^ \ f(x ,y ) • TAR(Ro,h') • r 7 f ( i | | ) •?D(P) . 100 *| ) . - £ - 2 (15)

\sSD * h / TAR(RO, h^) • I^J^ 1 (x .y) .

SSDr Ja refaranJnf rsd^lanoat edroj-po-rrah » SSD ja aJctuilni TXd<lamo«t »droj-poTreh. h ja korigoTani hloubka Oodu ? am "itkmf" prflchod tuikovflto ar»>slni. h"•poStama podia T»tahu (16).

y 2 ' s s p 2

SSO

DoatataSna* praanoatl rfyaitit Ja doaaiano pri rolba d. r • 1 CM, RQ - 0,5 o«a A 9 - 10°. Pro anargla fotonft vitSi oat 5 MaV Ja autn< TAR nakradlt tlaaua pha»-to» ratio.

?unkoa FBD(r.h) pro alaktronoT< w u l oJaJc rjplfri z praoi rady autorft L2,3] , l«a profll tulkor^ho aramku popaat po-

mooi Oauaora noraalniho roslolani. Funkol PBD(r.h) afllaaa podia [3] Tyjadrlt ra

PBD(r.h) =

h ja hloubka a W / J a atradnf kradratloka odoh^lka dhlu latu alaktroxn prl ano-honataobna'ii rotptylu r latoa. < 9 >apoita«a podia ratabu pnMHrnranfa • L • J • 'trad-ni anarsll alaktronu apoStaaa podia rsorea uradan<» T ^5j .Vyjdaaa-li • daflnioa prooantualnf hloubkoT< darkjr a TBtaka (17), doatanaaa p%jadaoduob/oh ilpraWfohc

J f(«,y).G(h).a"r '4 >&PP(P) = 100. —

- 23 -

ftinkol O(ta) Is* ryjtfdflt pfaa prooantualai hloubkorou da>ku nakonaona i iro-ktfho aTaekv*, pro ktartf plati » o . f (x,j)-P o # lakonacna air ok* n u i k laa r u U t o -T»t Straroov^a polaa axa, kda 0,5.a R .R Ja axtrapoloTani doaab alaktroas. Vatah

>pllkuj««* ns nakonadni *irolc# arutak • po lntagraol do«taa«««i

0(b) . O(hB).S(h) (20)

i(h) )t dino rovaloi (21).

3(h)<r2(h,)>

Doaadfaa (20) do (19) a po iipr»T» doat

P D - (h) C21)

(t) = 100. (2j ,

-•72 -t>72 '

V«t«h (15) • jX odTosm *• pf«dpokl«du, i» aruak do««d< kolae M peloi>«k«iaS-a* prortradi. V klinl«k4 praxl n*at4rtf Saato altuaoa, pfl ktar* arasak dofja44"•tkao" na povrata tala paolan«a (via. obr.8.4).

Oorraatlam of ebllau* inaldanaa

ot ,6.4

Baa •tra'tj praaaoatl laa aprozlaoyat prof l l araaku pro roaptyiani utrmi (Clanjaa T M t a t a l l a jaanoratall aloadra raoroa k r i t l (15) ) praroiUiifr roalo iaala . To-to ajadnoduianf ratahu (15) aal luja airoky aa v^pofiatnf Saa pfl jaho "jBimlmni.Zaradaniu korakoa aa "alka^" dopad do Teoroa (15) a ajadaoduaanla doatiTaM vatab (23 ) .

SD +L

Iddaktf talo naaplfluja pradpokla* boayiganniho proa trad £. T I I T hataroganaoatllit Yjjrfdflt nahraaaniH hloubky bodu ? pod povrehaa afaktlmi hloubkov. fradpokladpolonakonaonoatl proatfadl ami *4i aplaan. To arttla apftaoblt readily aaal •fo6«a>nou a aaifanou dirkou T oblaatl rfatupu arasku a tala p*ol«ata.

U alaktronof^oh arazlcfl ja altuaoa T kllaloktf praxl jalta koajpllkoTanajil.1. Spaktnai alaktrona jaJc anar(otloU tak aaaroTtf na porrakn airlaf aajaa ns

anarfll alaktrona prad rfmtvpwm m urjotaloraSa a roaptyloTtf falll, ala 1 n* T « 1 1 -koatl tubuau.

- 24 -

2. OauaoTO Bormrflnf roadalaai ni« T hlaubkioh •lXsk^oh R aapaplauja aprivaaroaloEan£ d<Tfcj T okoli tnikorAio »T»rfcu (vla.o»:r,S,9).

HBUTITK DO8B DISTanOTICBI Ot PMOU BMIM

«# - 12.2 HaT

h - 6 ea

Obr.iJ. 5

3. l«pl«tf itTeroory tikon pro iJbjtek fluanea aavrgl* alaktroaA a* Tsd<l«noat{od sdroj*.

2 tiohto dftTodft J« nuta< nahradlt funkkl S(h) T« Tttalna (22) bodaotaad. pToatm-tuelni hloubkori da>ky •zpcriaentiln* zurtn< pro daa^ tufcua. Ml* }m natatf pa-ulft i«Jf»n^ s^Tlalostl iSbytka fluanoa an«r(la aa Txd<lcnoatl od adroja T . fmdoaazani do rctahu (2?) doataXaa vsorao (24).

• i \ ' i

n . ( p > = (24)

a J h .'

V tabulo* S.i Jaou poroTriny •zparlaentilBa Baafaa^ • apo£t«a< hodaoty pro>oentuelnioh hloubkorfeh divak n* oaatrtflniai papraku pro ziraai gaa* Co OBATO-

rad« Chl*obalt, "• obr.2.6 a 5.7 Jaou porornaay azpariaantilBa cawfantf • apoStan<lsodotnf krlTky pro Xfi oaarorai.

Xa obrrfsku 5.8 jaou »po5t«n< laodoaal krlvkj pro alaktroaov^ avasak s batatro-au 6»«ko»lo»«n8k< rfrohj B 19. Hoadailai aaar(la alaktroafl 15 1I«T, atradni anar-gla aa porrohu 12,2 HaV.

Haxla^lni odob^lka aatl apodtaaou a •Mranoa proeantualai aloubkorou dtfvkov a*oantrllnfa papraku nani ratif aai 1% aaaraa4 bodaaty.Odohylky aaal axparlaaatilaa waaraaiad. • •po^taa^al laodonial krl.viwal v oalaatlTalkiho gredlaatu dtfvky jaon •anii aal 3 am.

r 25 -

I ' I I >H r"

Hit 111

•;MJ=HII cm

SSU'KO CM

r,xr,

SSU'lMl rn:IHX3H

ll

1

1(1

I ' l

I

r.InIT,

1!•

10

13

1:,

lu] ' .

M• • - . .

7 H .

r . ' . .. I M .

!>H.

7 H .

.r>(..

((7.7 3 .

•IB.

3 8 .

t l i l f

flfl.

70.ri!i.

::

i

:>

8

3

H

II

U

!,

1

7

4(i

Ll! • >

' h .

' H .

' • ' • .

I K ,

' IH .7 f i .

r><>.

3 9 .

'J7.7 3 .

4 8 .

3 7 .

Ul),

Bfi,

7 U .r.r>.

.!'•

r,

\t

1

8

3

8

l l

7

H

U

7

5

Tab. 5.1 dbr.S. 6

Obr. 8. 7

Polcamplrlak/ ««d«l tuikoT^oh arasM )• pro arojl pr««noat • fltzlbllltupro p*«it»8or4 plinovajii o««f«n£ r r«dlet*r*ptl.

Obr. č. 6

Literatura

1. Cumnin^haat J.R., Shrlvastava r.B., Wilkinaon J.M. : Program IRRBG^Calculatlon

of Dose from Irregularly ahapřd Radiation Beams. Computer Progr. in Biomed. 2. 192

(1972). _

2. Oaman C. t Deoreaent Curves in Therapeutlo Electron Beams and*Ťť?lr '!se im

Medlnal Computers, Aplled Radiology, September - October, 53 (1977).

3. Kozlov A.P., Shlslov V.A.: Calculation of high - energy eleotron UtM diatri-

butions in tissue - equiY*lent media. In: StreAlentheraple 158(1982) p.298-304.

4. Bethe H.A., AaMcin J.' Experimental Nucl*aj- Phy<loa, Vol I, fart II, Mew

York, John Wiley And Sons. 1953, p.166.

5. Klinická dosimetrie terapeutlokýoh fotonových a elettronov?oh a^a^M T obo-

ru energií 10 keV - 50 MeV. Aktuality z kUmiokej onkológle B (19B4).

6. Van de Celjn.t EtTDOS 71. Conpu*er Progr. in Biomed. 2 (1972).

7. Matula P. a kol.t Priapevok k raoionallsaoli vypočtu dlatribuoie d**vok T ae-

gavoltovej terapii. I.Statloká terapla. Cel. radiol. 27, 3, 1973. atr. 209.

8. Sterling T.D., Perry H., Weinkaa J.J.: Automation of radlAtloa treat-#nt

planning - Calculation and visualisation of the total treatment volant. Brlt.J.

Radiol. 38, 1965, 906.

PROGRAM FOR RADIOTHERAPY TREATMENT PLAJntna

J. Potměšil, J.Maeh,Faoulty Hospital - Computer Centre and Department of Radiotherapy,

PlteR, ČSSR

A computer program In FORTRAN has been written using the penoll-bemw model for

photon I and gamma -ray and eleotron*.This model make* possible a very natural dose calculation in the oase of i*ho-

- 2 7 -

mogeneity of the tisane, irregular fields, filters, eto. Static and dynamio plans

aa well as combinations of various sources ai*e possible.

Quasi 3-D plans are oaloulated and manually optimised lr an interactive way on

a computer of IBM PC/AT type.

1. Jvod

Důležitá místo v systému léčby onkologloných onemoonění zaujímá ]6<"ba ionlzu-

jíoím zářením. V současnosti ae využívají pro tyto účely technloky složitá zaří-

zení, jako např. kobaltová ozařovače, lineami uryohlovače, betatrouy, npeolálni

RTG přístroje.

Základní podmínkou úspěšné léčby Je, aby nádor byl kompletně a homogenně prozá-

řen a současně okolní zdravá a radiačně citlivá tkáň byla zasažena zářením mini-

málně. Toho lze dosáhnout správnou volbou ozařovaoího přístroje a optimální teoh-

nikou ozáření. Podkladem pro optimální volbu ozařovací teohniky je tzv. iaodozní

plán. Zde nastupuje na pomoc výpočetní technika, a matematické modely.

2. Matematické model

Základním předpokladem Bprávně vypočteného laodozního plánu je korektní mate-

matický model lnterakoe záření s tělem pacienta.

Na ror.óíl od systémů firea Siemens, Philips nebo Robotron, které využívají

empirických vztahů, jame rozpraonvali model "tužkovýoh" svazků publikovaný v (1)

a (2). i.dobný model je zatím učíván pro numerickou národnost jen ojediněle.

Podutttou moJelu je, ie dávku v libovolnétr bodě těla paoienta od svazku ioni-

tujíoího z4ř*ní lze vypoííst lntegraoí "tuikovýoh" svazků, na které je tmkroako-

ploký svazek rozloíen.

Tento model má několik záaadníoh výhod: dává nejpřesnějíí výsledky, je velice

flexibilní (umožňuje výpočty pro svazky libovolného tvaru a flltraoa), vychází

z fyzikální podstaty Interakce záření a látkou a lze snadno konstruovat 3 t plá-

ny. Blliěí popis modelu pro zářeni X a gamma je v (3) a v předchozím referátu

autorů na tomto setkání.

3. Popis softwareovýoh prostředků ONPLAB

Systém ONPLAN klade na základní software tyto pořadavky: operační systém pro

praol v reálném čase (interakoe), kompilátor Portranu, výhodný je soubor progra-

mů pro grafiku.

Hlavními programy systému ONPLAN jsou PLAN a BRACH. Tyto prograny si aohou at-

zivýsledky předávat přes diskový soubor EIT, čshei se vyu!íva při léčbě gyntkolo-

glokýoh nádorů (kombinuje se externí a interní ozářeni paolsntky).

Programy jsou modulárně stavěny, přičmi byly dodržovány zásady atrukturovan4-

ho pmgramováni (pokud to nebylo příllč na úkor ryohlosti výpočtu).

Program PIAN obsahuje tyto základní modulyt

INPE - interaktivní zadávání parametrů pacienta (nožno uHt výstup z počí-

tačového tomografu),

M A M - interaktivní <*<l4v<ní a opravy pAr*astrt o<#J-ovMÍoh swMků,

COMPK - výpočet matloe dávek v těls paoltntl,

EITRW - čtení a zápis dat z diskového souboru EIT,

ISOD - výpočet isodořníoh křivek z aatloa 4áv#k,

DISPL - zobrazeni lsodozní distribuce Y til* paoltnt* na obrazoTos (grafla-

ké, alfanumerické),

PLOTT - vykresli na plotteru (tiskárně) lsodotni dlxtribuoi.

Program P L H j* již dlouhou dobu dspěfn* pouiiyáa * průběžná zdokonalován.

Program BRACH obsahuj* tyto moduly!

INPB - Interaktivní zadáni dat ptolsntt,

SOURCE * lnt*raktlvni ttdáni zdrojA v t*l* paol*nta.

- 2 8 -

*OPTIM - výpočet optimální volby aktivity zdrojů.

OOMFB - výpočet dávkové mříža v rovině (eagltální, frontální, transverzál-

ní).

I30D - výpočet lsodozních křivek z matice dávek,

B3CTRW - čtení * ^4pla Bouboru RXT,

DISPL - zobra"-í loodozní distribuce na obrazové*,

PLOTT - vytcrpf! t plotteru (tiskáme) iaodozní dlatrlbuol.

Praoovník veda 'i.^, a počítačem pomooí klávesnice a alfanumerická obrazov-

ky. Nojd :'v tadá ; Mt-t -y oaclenta, pak ozařovaoí svazky. Počítač vypočte lso-

doznf rozloíení R x< trazi Je na obrazovku. Lákař poaoudí vhodnost otířeni. Pokud

je nevyhovujíoí, zmtní potrametry ezařovaoioh avazkú, a stroj opět zpoBte rotlaíe-

ní. Tento prooeo pokračuje do doby, ne! se nalezne vyhovujíoí "optimální" plán.

Potoč* ae naohá lsodozni plán vykreslit na plotteru nebo vytisknout na tiskáme.

Programy PLAN a BRACH potřebují tyto diskové soubory!

POP - aoubor geometrlokýoh parametrů pacientů (max. 100 pao.), 100 kB,

POS - aoubor te.belovanýoh funkcí ozařovařú a zářičů, 250 kB,

EXT - aoubor mátlo dávek (max. 20 paolentů), 270 kB.

Ostatní programy v cystámu ONPLAN slouží ke zpraoování eiperlmentálníoh dat o

ozařovačíoh e. k uložení do diekováho aouboru POS.

System programů ONPLAN umoínuja přesný výpočet isodozníoh plánů pro tyto tech-

niky ozáření: teohnika víoe polí, kyvadlová a rotařní ozáření leocentrloká a e^ea-

trloká, klínová filtry a nepravidelně tvarovaná pole, tcombinaoe rnznýoh druhů zá-

ření (I, ganrnna, rychlá elektrony), kombinace externího ozáření a brachyterapie,

výpoí!et jak v "oentrální* tinnaverzální rovině, tak v rovlnáoh rovnoběznýoh (kva-

zl 3D plánováaí).

4. Ponls hardwtyeovych oro<tredků ONřLA!!

3ystám OHPIAN vyžaduje tyto hardwa)c#ová prostředky: počítač se 126 kB operač-

ní pamětí a s rychlostí minimálně 150 000 operací/seo. Vnějáí diskovou paměť 1MB,

grafloký display (v nouzi alfanumerický), tiskárna, (plotter, dlglte-lisátor).

Poslední dvě zařízení nejsou nutná, ale velice usnadňují práci.

Z toho plyne, ía systém OHPLM! lze provozovat!

a) na minipočítačích (např. PDP 11/34, SM 52/11, ...) neb-í vyltonn?oh prof*aio-

aalníoh osobních počítačioh (IBM PC XT, PP 04, ...) maistěnýoh přímo na radiote-

rapeutlokám oddělení^

b) na nUtropočítačl přlpojenám aa počítač, který je mimo RT oddělení (mikropo-

čítač provádí dialog a zobrazení dávková distrlbuoa, po!ít*B provádí časově nároč-

ný výpočet dávková matice)^

o) na jednoduoháa termimálw spojenám s centrálním počítače*, bohu!*l obvykle

bez graflokýoh perlfárlí.

5. Závěr

Systám OHPMJt je vyzkoušen a provozován na počítači Vldeoton K 10 11 ve výpo-

četním středisku fakultní nemoonloe Plzeň. Podle lsodozníoh plánů vypočtených sy#-

támeo 0NPMN bylo k dneBnimu 4ni ozářeno pros 400 paolentů.

Uteratnr*:

1. ?.H.Attix nt til.! Radls-tion dosimetyy, Vol. 3. Aeoad. Pres*, Wew York 1969.

2. A.P.Koslov, V.A.ShlsloY! Calculation of doma distributions In tissue-equi-

valent media. In! Strahltnthwrtpiw 15B (1982) 3, Z98-304.

3. J.M*oh, J.PotoěMl! Poloeeiplriak^ model svazkn tářtni JC a ^ p r o

plánování láčby. Int Aktcmlity z kliníeká onhoit.%* 4 Í19B3). 135-141.

- 29 -

OPTIMALIZATIOH OF RADIOTHERAPY

g Ca MAMMAE

0. Raeovekii, A.Halir, V.Krystof, Z.Kuallckova:, J.Peolna

Striking ohangea in th« therapy of Ca mamma* hava ocourred In recent 10 yea

A numbar of ouoologloal olinios both la Europe and th« D.S.A. prefer conservati-

ve surgical lntarrentlon, euoh aa local rtsaotlon or segmenteotomy, to total ma»-

taotomy. Thaaa perfonnanoea ara furtharnora aeoured by adjuvant hornona or ohe-

motherapy and poat-oparatlra irradiation of tha namna or lta regional lyaphatlo

ration. Thin more and mora patlanta with dlagnoaad Ca manaaa ooae to radlothera-

pinta with tha raqulraoant to lmprora thalr quality of Ufa, to diminish tha po-

•albilltlaa of looal tumour raourranoa and to gat a satlafaotory ooamatlo effect*

Omitting tha importance of aatabllahlng optimal value of tumoroua lethal do-

aia and Ita tima distribution, It la naoaaaary to ooma out of tha most aocurata

topometry whan oomplatlag tha plan of Irradiation. That means to alaborata topo-

matrloally the target sphere and to limit aoourately the irradiated volume.

Tha looatlon of primary tumour in the mammae with reapeot to the easy aooessl-

billty of this organ for ollnioal examination and tha aoourata demarcation of tu-

•oroua lanlon on tha nanMacran la not a (raat problem fe» tha radlotharapiat. Tha

Slnoa a routine performing of lynphography and aolntlgraphy la lapoaalble, tha

uaa of modern teohnlque - simulator and oomputar tomography - prorldas an Ideal

altarnatlra.

Particularly CT la a valuable contribution for topometry because it gives tha

acourate oontour and survey of anatomical arrangement of the relevant body region

and the CT finding la alao a baaa for individual demarcation of the target region.

To find tha looatlon of aoma groupa of axillary nodea, whloh ara not oontree-

tlng aufflolently in the CT ploture, upper extremity lymphography waa oarrled out

In a few patlanta.

Another requirement for the radlotheraplat la homogeneoua thorough Irradiation

of ti»a target region. Any non-homogeneity oan threaten aerioualy the result of ra-

diotherapy. Lower dosing leads to recurrenoy, over-dosing to the damage to healthy

tlsauea.

- 4*7

n.g. 1 W g . 2

Thla risk la particularly great In the aupraolavioular and ailliar region* whieh

ara vary delioate araaa from tha view of anatomy. Hemogeneoue distribution of tha

doala la given by tha properly ohoaan teohnique of Irradiation and acourata appli-

cation of Irradiation paraaeteraS

- 30 -

FRONT326

ILEFT

7«

- 186

Fig. 3

Our ollnlo was equipped with the

pluming unit EVA DOS oonneoted with

CT and thua had varlflad tha uaad Irra-

diation teohnlquaa and, at tha same tl-

M , we oould arrange Individually stan-

dard techniques of Irradiation and aoeu-

rate oriantation of tha distribution ot

tha dosls In tha whola irradiated vo-

lume.

For Irradiating the manna, our de-

partment has baan using olassloal tech-

nlqua of 2 tangantial opposite fialda

In a eobalt lrradlator. Optimal plan

wue made by tha planning system EVAD03

on tha baaa of tha CT soan In Individual patla&t. 'Wg. 1)

Whan postoparatlra Irradiation la lndloatad aftar maateotomy, tha Irradiation

of thorao4o wall by maans of aro tharepy with aooalaratad eleotrons is considered

aa optimum. Thus, wa oan proteot la tha bast way tha adjaoent orltloal organ -

pulmonary paranohyma - and tha sultabla distribution of tha Irradiation dosia Is

obtained In tha raqulrad volume of the thoraolo wall and retrosternal space, (fig, t)

A CI seatlon, besides contours of tha thorax, gives us information on the thick-

noes of tha thoracio wall and oan help to determine tha needed energy of electrone.

Whan choosing Irradiation teohnlques determined tor the Irradiation of lympha-

tic area In tha supraclavioular region and tha axilla ws hare elaborated our own

technique. It is the irradiation ot tha subolarioular and axillar region* from 2

fields with a radio-cobalt irradiator with the tilt ot head and the use of the

wadgs filter adjusted to the axillar area. Tha general validity ot the takax re-

ference point for tha subolavloular region has been verified by simulator and CT.

Tha prerequisite for optlmlzatlng this teohnique la to plaoa tha patient into stan-

dard position whioh la not ohanged during tha prooadura and thus unplanned orosslng

of irradiation bean balow tba aurfaoe of Input fialda eannot o«o«r aa It oan ba •

seen in other techniques of Irradiation whan eaoh field Is Irradiated In another

position of tha patient. (?ig. 3)

Tha justifiable using of our Irradiation teohnique has been verified by ellal-

oal expsrianoes. In patienta, who underwent this method, a aaall number of post-

lrradiatioa changes oan ba observed (flbroinduration, oedemaa or neurologleal signs

of daoage in oerrloobraohlal plaxua) with eatlafylng therapeuttoal effaeta.

- 31 -

OUR EXPERIENCESWITH BRACHYTlffiRAFT TR3ATMEKT PIABHIBO

B. PleSko, V. I*R inoT(i, J . Ka l lay , D. Keder, G. Kra l lk ,

Institute of Clinical Pnooiogj, Bratislava

3umpaxy

Rain>if»lv n u n l n i l l w i • T tm r l omi I ng •jrntanm liavn h e a n 1 n t rortiioed In many o e n t r a s

b e o a u a a nC I h a l r nrt vmi tn,.'Biui«i j i u j j o r l 1 a a . T h i s p a p e r w i l l flenorlhe t w o - y e a r a e i -

perjenoe with .'leleolron !.!'R afterLondlng syntesi In tha treatment of utarlna oei«-vlx carcinoma. Ns<:»««nry data for axaot braohy therapy tr»ati»ent planning - loca-lization of tha appl 1 ohlor, aouroao and eceoiflsd polnta related to tha organ atrlak ara obtalnad hy orthogonal X-ray projaotlonii. Spaclal tiox 1« uaad for aasyoorraotlon In can» of oblique projection or dlff«r»nt aouro»-fllm 'llBtunoa. Traat-ment plniinlng la mndit by i.noology Support Syatam.

Comparifion of computad plans with In vivo ! r, s 1 me t ry ahowa good epreement. Po-ea dlntrlbution of oblique application i s optimized either by number of nouroaa

_and irradiation time or by modified teletherapjf. _. _ _ . _Carcinoma of the utarlne cervix ie on the second plaoe of cancer incidence In

'nrhfin i ovak women. Intracevitaxy radiotherapy is one of the moat sucoesful »a-thnd« r.f treatment this aiaiioor. We ciui art an offort in many radiotherapy car.treotc im;i-(ve Intrecavitary mil olh«rdpy. A Buhatv.lial contribution to the Improve-ment «re tha remotely controlled afterloadlng ayatana. At praaant two baaio typsc

drf [if>« r i'.ow doe* r«ta and hlph deer rate. Adrantagoa wnA diafl'ivaji)«>•<?« ot »achtypo (ire nt l l l under diBCUBaion. Some of them «re phown tn table I.

TaMe I .I. I B

Radltttl- ; ro-trction . t P'laffand roomProtmuttonLarper refficiency

p

j e« with ' '<6Ra appl.-1-2 fraction*

137,

T ~ • _ " "

j - J'atl rnt im-

: ir.obllioation

for 10 '* hour*

- orly for in-

door patienta

- long duration

of application

chang*B in

lrradlnt.g»om.

1... H r< R "1

1..

- Radiation

protection

of etaff

- ahort dura-

tion of

application ji

- for out - '

door patients ;

- constant geom.i

5 or more

fraction?

nbeolutaly

'•'-t r

lower Hoi

• fficlmiry

Radiation

Frottction

of Roon

LT>R Saleotron Afterloadlng hae been Installed in our Inatltu'n of :ii-

nloal Oncology in Bratlalara. After lnntalatlon (May 1 84'< <?00 patients hnvr h»«n

treated at the gynaecological department! 194 cervical aarcinomnt

6 vaginal oarolnoaai

Patltnta with cerrical carcinoma mw» mostly in clinical stage II for all

patiente supplementary parametrlal and pelvic external beaa radlother>py waa de-

livered through AP opposed cobalt or 42 HeV I-ray fields.

Necessary data for exaot brachytherapy planning) Position of aplloatore, sour-

oea and specified points related to organ* at rlak are obtained by orthogonal

I-ray projections - fig. 1. Tha bladdar refaraaoa point is detarmlned In agrae-

niant with ICRU report 38. The baloon of the Foley catheter la fillrd with 7 on

of radio-opaque fluid. Tha referenoe point la taken at tha posterior surface on

- 32 -

thf Intern!! projection, and at the center of th*> baloon on the A! pr<'\) option. Theposit ion of the reot«l wall 1B vimialiapd by op*rlficntlon of the r^rtftl cavitywith cor.trnjit medium in cotxiomn. Projections ar« mnde by rila#no»tlc X-riy unit .»i>r the ] oca] 1 nation of appllcatore more simple and mor« reprodwnibl p p-o-e-'urewith a Bpt-oiaj film cassette holder 1B used. Rxcept ui-ual mnrkere i t "u tnlnj fourlep.d •troBffwlrea with defined nizea embedded in the walln of ths film holder. Pro*the enlnrgpmeijt of the anterior projected crospwlre by simple algorithm we can ma-ke source - film dlfitarice correction. Prom the nhifting of ar.terior firu* posteriorcrosnwtrep projections we ORE rn«ke correction in cape of nor. exactly •• r*!>o.-THIloVliquei projection. I'Bta obtained by loca l i sa t ion prooedure together »1!h r)i~nical data about s ize and extent of tumor nre necasaary for the c«l- .; lst 1 .n of do-se diptrlbution. Calculations are performed by Philips OSK trea'mer.t pip.r.nlng ny«-tem by using Veisberger-Shftlek calculation model. DOBS diptribution nre mostly ni»-playeii in frontal or sag i t ta l plane. Pone J i etrlbution ploted 'iireotly or inieralfilm with doe» to organ at risk In recommended an wel l . In our 1 4 appl1"6'l"nn thelength of the. in'rauterlne tub* was 4-11 cm anrt number of the souroee *-7 r-f i,4PC,Pq eaoh, ? ovclda with ? souroe.q ? l 1,40 ".Rq. It meaun tlmt th» refe'^ti^e nirkorroa rate was 0,7?1 - 1,1?? mtiy.h at 1 m ami total reference air kei-raa • ,&> -4,4>S cGy at 1 m in two appl icat ions. Total doee TA - 60 fly, total dura*ior of tr»nt-mprt 36 - 4R fours, treatment performed in two appl icat ions.

•"laleulatlons for a l l patients had been verif ied by in vivo dosimetry in re-mimand bladder, and our praotlce confirmed I t s necess i ty . ?h» measuring probe i s mo-Ted so that the t ip of the probe move a along the tnldlin* of the recto-vaplnal :>»p-tuis ur.til the point of maximum dose rate i s reaohed. Measuring in the bladder 1»done in a similar way. Maximal done rates and depths distances are recorded. -'Ti-the baeia of in vivo donimetry we decrease the to ta l dose In 10 appl icat ions. - urexperience also showed that In TITO doalraetrj in both application* 1* needed. On thefollowing examples - f i g . 2, f i g . J we can see 1 and ?n application of the samepatient . Localization projections are almost Ident ical , but aeasured values increa-sed in the bladder from 13,8 Gy to 1S,1 Gy and in the rectun from 1?,R Gy to ; 4 , iGy. During ? and half year of c l ln ioa l routine work of afterloadlng we have had onlj1 small fa i lure . The ftystem proved to be very r e l i a b l e .

Conclusion

Afterloading LDR 1B advantageous for c l i n i c a l work. After loca l i sat ion proc«flu-r«, starting of treatment and ranking in vivo doe ira? try, we can compare resul ts of;)0 8lmetry with the calculation of dose distr ibution or the dope delivered to spe-c i f ied points related to organs at r isk, and make corrections. Our preotloe con-firms that In vivo doaimetry Is necessary.

Our aim i s a complex optimization of cervix uteri treatment by col«botmtion withthe reaearoh work of the departmeats of radiotherapy, gynaecology, radioblology.We would l ike to invest igate radioblologioal aspects to introduoe the Integral *L-ctoalaetry of complete treataent duration, to reach BO re aoourftte topoaetrlo infor-mations by CT, and treataent planning of external beaa radiotherapy together withbrachytherapy considering their different radloblologloal effeota.

- 3 3 -

COMPLEI DOSE fLAWINO

C!) IRM CQMI'ATIBLE PC

)t. Katnna, J. Polgar, r. Zarand,

^ell Hmll HoH;,lt.al

Onnoradiology Centre

Uzeottl u. ?9. H-1145 Budapest, Hungry

Summary

The authors have dsveloped * oomplex irradiation treatment planning program.

Th< pr'-nram la adequate for the oaloulatlon of the doae distribution of both *x

t*rt)*i mtd lntomal Irradiation aa well as for the almulation of the repro'tuolbl-

H'.y of the tr**tm#nt t'lan at pointo «r Hn*s of fnt*r*st. The *r.<hlv*t]nn and th#

Bta(tnl)'n) c^^lm.)on of th* p*H#n<.c* <tn<) trxotmant d<t« 0<<n b< ta«<l# hy th* )'"'<*

ratti. Mhurt <1«K''.rlp<.lon "f t'mlr JhM oompatlht* [it'onrim mt(! the o<opm!t«<tt <f o*l-

(tul<it*d «!!() meawurMd don* dlatrlbutlon M*< pr<a*ct*d. An *:<unpl< in Rlv*n fr.r th*

quality nasuranc* of thu radiation treatment.

lH{r.c<luctipn

'hf computer Asalated doae planning start*d in Hung*jy in 1970 by using th* mo-

dified van d" Geijn program (1) on a oentral computor in Budapest. Thin program

car; he ufted only for the planning of external irradiations, and the criminal fle-

xibility is atrongly limited ty the local hardware configuration tthe interacti-

vity ia lost, the doae matrix is nit available, etc.). The shortcomings of the pre-

«ect ayetem aa well aa the rapid deoreaae of oomputer prloes initiated the deve-

lopment of e program ayatez, which ia adequate for the oaloulatlon of the doae dl-

atrlhution of hoth external and internal Irradiations, as well aa for the almtla-

tlon of the roproduclMllty of a treatmont plan at points of interest or in aeleo-

t*d directions. The ayatem permits the arohdvatlon of the plans.

r.hprt deaoriptlon of tho program

ThH prt< ram Hyotem t-nnalats of four main parts (Pig. 1). The Tl.I.KPOSF progr**

(i'i In uned for tha calculation of the doae distribution due to external irradla-

tlůna. The abeorbfd doae at sanh point ia calculated on the base nf the penoll b*e^.

mn.lHl. ?or an opnn fiald the doae at the point F (Pig. 2) la given aa

!< Í ;<M.'l- *<TAh;':^.,i. H;'F<ttf.;W{ ;.;.[..,tn,< ':.]).,.)) .,

*[ y.;:, 11 *t'Y' '!,<« , <ni r )*Ri ri

where Uc ia the equivalent field site at a depth of d, PX and MY Are the dose pro-

files of the field U V, G(x,y,z) and B(x,y,t) deaoribe the effect of wedge and

block filter, reap. (For the other symbols see Fig. 2). The maximum number of fields

la limited for both staying and moving fields for prtotloal reasons as nine, the

maximum number of oroas sections is five.

In fig. 3, aa an example dosimstrio oontrol of a wedged field (3) can be aeen.

Th* caloulated ant) the meaaured dose values are given in the figure in three diffe-

rent dept.ris.LiF:Mg, Tl rods and Kodak-IV-2 fllma were used. Detalla of the teohnlqu*

are given in (4) (5).

The program TELEHIBA (6) la written for the estlntlon of the laoit of eiaot re-

pro^iuf-lUllty of the lrradlatlpn geometry. The differences between planned and ao-

tual values of the field parameters (flsld slse. SSD, or position of the axis, angle

- 34 -

F'lD

ii-'

Fig.

, . i I..-.

V.

rig. 2Mg. 3

of tha oentral baam, or uncertainties In tha starting and final angles of ara

therapy) arc assumed to be governed by Gauaaian distributions. Tba treatment pa-

ramatara of tha TELEDOSK program ara tha azpactad values. Th« standard darlatlona

(dependent on tha therapy unit) ara determined on amplrloal baala. Tha affaot of

unoartalntlea of tha traatmant parameters on tha abaorbad doaa at given pelnta

or Unas la simulated by Mont* Carlo method. This prograa la uaad for tha plan-

ning *nd evaluation of tha doalmetrlo oheok-up of a treatment plan and oan be

uaad for oli'WMilnc the appropriate treatment rt«l»e. Two oblique field Irradia-

tions of e brxin tumour are (Iran In Tig. 4, with the attacking of tha tlaa aelaa-

tad polnta. The variation of the doaa determined by th« Monte Carlo aethod In

tha sagittal Una la given In h g . 5. The solid llnea represent the 95* conflden-

oa Interval deteralned froa n • 30 slaulatlons. It la not siaantrloal dua to tha

Iff1

>. "•'-v\\>' J- > "s.

i "

•M

j

Pig. 4 Fig. 5

change of the dose gradient, and the width of the confidence interval depends on

the absolute value of the doe* gradient. The average values are signed by z. The>

dashed line represents the planned value. In oertaln pointa tha deviation of a

alngle irradiation may be exaaptlonally high and the average may considerably

differ from the expeoted value. Aocordlng to detailed analyala In these pointa

at leaat five measurements should be used for the oontrol of the doa* distribu-

tion. The Monte Carlo simulations of the does uncertainties in Pig. 5. war* con-

trolled by the irradiation of 30 films. The average doae and tba standard devia-

tion were equal within the limits of the error.

Thtt BRACHYDOSE program (7) oalsulates the absorbed dose of the lnterstlclal

or lntraoavital radiation treatment. Standard souroes (line , plate constructed

from five line souroea, ring, mushroom) are approximated as a aum of point sour-

oes. (Pig. 6). Tha effeoilva linear absorption ooeffioent.ytC (eff) la ajeaeurad

In water phantom with lonleatlon ohaaber an TLD's. The position of the souroes

is reconstructed on the base of topometrlo X-ray films by the program. The doaa0 i 10 1'r v r~ \ '

1 1 <

\ r

,!

_ I• \

S 10 15

Pig. 6

- 36 -

oaloulatlona war* o out roll ad In • aolid atata phantom with Harahaw TL rod a (7).

A part of the oeasurementa la given In Fig. 7. Calculated (ltnaa) and aeaaurad

/slues (ayabola) ara compared In rarlotw dlreotiona.

The doaa distribution of ttaa programs BRACHYDOSE aad TELKDOSB can be auaaarl-

«ed if required with or without appropriate weighting (Pig. 9 ) .

Tba arohlTation of tha patienta'and tba treat-

aenta Input data la aolrad by tba ARCHD03B pro-

gram (9). By aeana of tba program atatlatloal1 ' evaluation of tba treatment plana and taohnlquaa

(10) oaa ba carried ont.

: "-•' Dlaouaalon and conolualon

Tha aeouraoy of tba TEI2D0SB oaloulatione la

In aooordanoa with tha ICRtJ prescrlptlone and Is

•lallar to that publlehad 1B Raf. (11) for tba

ran da Galjn program. In tha braohytharapy thara

M-S* s la no International agraaaant on tba aeouraoy n-

qulrad. looordlng to our opinion tba oaloulatad doaa ahould ba aa oloaa to tha

maaa\ir«d ralua aa poaalbla In tba high doaa ragloa (tuaour, or In point A, a.g.)

and lowar aoouraoy oan ba aooaptad aararal OB. froa tba aourea (a.g. Is point B).

Tha uaaga of our program ayataa paralttad aararal naw taohnlquaa tn our lnatlta-

ta (12.13). All part a of tba aya.taa oan ba uaed aaparataljr and 1B any naoacaMrjr-

oomblnatlon In our routlna traataant planning.

At praaant thara la no llnao in oar Onooradlologloal Cantra. la tha naa^ futa-

T*, bowarar, axtanalon of tba TELEDOSI program for high anargy I-ray and alaotroa

Irradiation la planned. A dlraot uaa of CT pioturea froa a floppy dlae la a i m

taken In acoount.

Raferanoea

1. Hokhardt, S., at all. 1981, Hagy.Onkol.^, 157.

2. Katona, B.t Folgar, I., Zarand.P., 1986. Xorhaa - a* Orroataob. 21• 52.

3. Katona, E,t Zarand, P., Polgar, I., Magy. Radlol. (la praaa).

4. Zarand, P., Polgar, I., Katona, I., *ela>. Cm., 1983. Korbas - aa Orroataok.

il. 161.

5. Welni, C«., 1984. Magy. Onkol. j£. 285.

6. Katona, K., Zarand, P., 1986. Korbaa- aa Orroataoh. j^. 138.

7. Polgar, I., Katona, B., Zarand, P., 1986. Korbaa - aa Orroataoh. 24. 85.

8. Polgar, I., Katona, B.t Zarand, P., Hagy.Radlol. (la praaa)

9. Katona, B.t Polgar, I., Zarand, P., 1986. Korhaa - aa Orroateoh. J£. 56.

10. Katona, E., Zarand, P., Polgar, X., Weias, Oa., laaath, Qy., aagy. Onkol.

(la praaa)

11. ZCXn 24. Dateralnatlen of abaoraad doaa la a patlant lrradlatad by kaaaa

of I- or gaaiM raya la radiatharapy fraaaduraa. ICIO. Vaahlactaa. 0.0. 197*.

- 37 -

II. C L I N I C A L D O S I M I T R TII. K L I K I C l i l D O Z I N I T F I A

TOTAL

C. J. Karianrk, Ph.P.,

Departaent ef nadlelejry

St'nferd Univereity :,rheel ef Medicine,

Jtanferd, California, U.:i.A. 94 JO1)

1. I n t r e d u c t i e n

Thia repert describee the techniiuee "nd deaiaetry far Tetal .skin Kleetreii

Therapy /T.ikT/ at ener«iea af sbeut 3-7 MeV at the patient and 4-1C MeT at ttia

accelerater. The irrsdibtien beea reiuireamla are identified an the baaia ef

cl inleM need far the treat Bent ef nycesie fun?eidea, a chronic preprennive lya-

pheaa, seat eften treated with TSET. MetheJa mt abtalnin^r the very larf-e fiaK'a

ae*de4 far elect ran beaa lrradiatlan ef the t r i a l akin are reviewed. r f rm»r . -

datlana ><ra aade regarding the type a tf daeiaetrle amaaureaenta 'h»t («^•nl1 be

perferaed prier te init iating auch irradiatian preea4urea. One widely v**A teebni-

lue fer T^TTT, which in»ol»ea ei» dual-fielda, ia deecribe* tharoujrt.ly en* etrer*

era reviewed briefly. An AAPli Teak Greup ia prenently rreparmjr a rretarel pr i -

•ar i ly fer «he nvdiral radielaxical physiclat wha nijrht wish te iarlxaent a TS«T

develapa)»nt pre^raa fer a particular eiuipaent at a specific fac i l i ty . I t in-

cludea • ceajprehensive blbl ia^raphy.

A T.iET pre?ra» develapnent ie heavily dependent T, the »p«cif!r t » ' l r ; :u»

ches»n, t .e particular equipment an which i t ia carried eut sn<1 the faci l i ty

»h«re i t wi l l be iapleaented. Eaphasie 18 placed an treataent with elertren l i -

niea, which ere freiuently eaplayed fT thie treataent aedalitv. The tec^nnuee

theaeelvea are eften cearlex wi<h canraait<>nt h*tard« r'nd aaat -<re t iae ronau-

• in(r te -levelep -inrt r'-rry eut en a reutine baaia. A ripereua TU'ljty assurance

?rtj?rs» «h.enld be an irte^rel p-rt af a TJIT prejrree which invalv»«e hi^h rtasa

r'ltea et ieocenter in arder te r in ia | ia treataent t iae in • r lane «e7»rel aetera

distant. Thia entaile aparatinx 'ha acceleratar at beaa currents raaparalle te

the»e u«»d in X-rey therapy which îves riee to the M*r. "leetren des* r-.t« »t

lsec*nter. It alae raûirea attantian ta aafety aeaaures; i .e . , ln'erierks, r<eaa

inv, written precadurea, etc.

n teaa raTuiraaenta

"he irret?iati»n beaa re<;ui reaenta invel»e eharecterietica af the trea»a»nt

electren bena, the diaeaae entity and the patient aepulatien. Aa «D»rified in

Table I they include specifieitien af: f ield aise, penetratien, energy, dca«, doa*

rPte, field flatneae in the treataent plane, th<» X-r^y background, the n»ed far

and nature 9t beeat fielda te?ether with patient ceneider' tiana. We assuae it

stnndinr patient since aast tre>i»aant technique* involve thia aatirnt naeitian.

The c»ntr%l reauireaerta are ta treat virtually the entire bedy surface ta a l i -

aitad depth and ta a unifer-a deaa usinx elec^rana and with " law X-ray backftraund.

Theaa reûireaente ceurled with the varied ebliquity af bedy aurfacaa and teeaa

- 36 -

directions, self-shielding, etc. ceabine in • c n r l n m>r.r>ur to rreduce • lessuniferr 4eae distribution thsn desirable »n<J eipnifie«ntly lees anifera than farcenventienal SB»11 f ield treataent aednlitiee.

The f ield else «f the ceapeelte electron been at the patient t£«s.taent plaaeauat be spprexiartely 200 cm x 80 ca in erees seetian ta enceapasa tha largestpatient. Within this rectan/ele, a vertical unifaralty ef ~ *% «nd * reriier.talunifamity ef - 4% aver the cenlrnl 160 ca r 60 cm orae ef tha treetaenl pinna' re an Mchieveble geal for cast techniques. Tha requisite penetratien dapth va-ries with the stage and type af disease and aay vary ever the hady aurfuce. * pt-netratian denth i-bnfe fraa «ppraxin'taly 0.5 cm ta 1.5 ea at the 50* isadssa sur-face enceaaaaeea aast lesiana. I t appeal* e.drmntageou# to prorld* i o n than on*TSET best energy to carer this r»n*e ef depths. Since asny electrajie enter ba4ysurfacea ebliquely, the energy require* ».t the ftetient traataent plana far a epe-cified average penetratian depth m the 50* isadase le»el ia si^nificnntly ^re*tarth»n ebtalned fraa invaking the siapllatlc energy leas «pprexi»j«iely mt 2 M«V/p.cii / . Haat irradiatien techniiuaa invalva s ipn i f icn t energy las» fraa tha se-quence af nuterials tr^Tersed by the alectren beaa, at auet »» efv^ral JleV hatveeathe accalaratar racuua and tha pttient trcatnent pl«na. Often, there »re touiy area aehielrtea in prrt by ether bedy sectlens er jna-ieiuately orpased btrausa af l i r i t a -tiana af tha geecetry af the treatnent technique. Sa»ll suppleaentary ba»et fialca•t electrana i r artharaltege X-rays «re therefare frequently needed. The ae/?a»el-t«ge X-ray br ckfrreund la p-netrating; i t nay expaae a si/rnif jesnt pertian ef thebedy volune »>nd therafara «ust be as law as reasenebly achievable. A deeir-tbleX-ray b-ckgraund lerel nrera^ad arar the bady reluae is 1» T leas ef the tetalaean eleetren daae at dase nxxiaua. This is d i f f icul t ta achieve »itb »»?t eouip-•ent and techniiuea. A repr«sentatiTa treataent Freacriptian is 36 n, i,, a i B -

««take, Riven faur d.ya par weak by three dual fields per day at 1 Gy per day. MeatTSn preceduree «re tiae coneuaing ta c^rry aut becauoe af the ault i» le- f ieW andaultiple-p»tlsnt-pesitien reouireaenta. Since patients requiring TSW ara a f t «

elderly pnd inf i ra , a high <1ese rate at the p«tiant treataent plane which shertmatha treataent tiaa is desirable. Arerage dase rates frea 0.25 t» sever.] Oys perainute at tha patlant depth dese aaziaua ara us«4, with the lawar ana mt tha w»a-ga cansldered a in iael . Sena patienta require physical suppart devices ta enaurath«ir safety as wall aa cerrect peeitianing in a a tending pasitlaa. JaXHatiaashielding ef spocific anateaical surfacs* *r argans aay «:»» be raquirad. Caaaan-l y , fingers, tea nails and the eyas are pretectea during treataant.

K1. Treataent fiels" alia

2. Baa* penatratien depth

3. lleetren energy at traataeatpltne

i 4. rield flatness in treataent

j plana

5. X- b'akgrauna

6. Preacribea' dasa

7. Daaa rate at treataent plane

P. Beast f l eUa

9. Fatieat »aaitianlng

10. Special artlent aaala

T»ble I.TS1T

- 39 -

Irradiation tephn.iq.u.ea.

TiiET la nuw In 11« fourth d*oad* of uaa. Prior to th* uaa of #laotrnn heama,

l.iw nnarK.v X-raya war* ua*d fur total akin Irradiation hut pranantlT hav* limi-

ted UBOK«. The ollnloal result! using a vaiiety of such X-rays were less encou-

raging because It was difficult to treat the total skin area adequately beoauaa

of field size and Junotlon limitations and, depending on the technique usad, to

treat an adequate depth without a large X-ray Integral dosa. Historically, ma-

chine-produced fileotrons have been uaed with an energy range of 1.5 MeV to 10 lleT

(prior to scatterera, Ion chambers, etc.) for TSET. Electron beams from acoela-

ratora show the typloal oharacteriatios of a maximum dosa occurlng Just below

a normally incident skin surfaoa and a rapid fall-off of dosa with tfepth to a

maximum rang* determined by the inoldent eleotron energy. The Van da Gr«a'i ge-

nerator, whioh was the firat accelerator employed for TSET, has been largely

supplanted by the lsooentrioally mounted eleotron llnao. It is necessary to taka

suitable precautions in the use of accelerator produced eleotrons to achieve

a low X-ray baokground In the treatment procedures and to make certain that tha

high accelerator beam ourrente used are properly monitored so that overexposures

are not inadvertently administered.

Studies have been oarried out by several centers to determine dose distribu-

tions obtained for single field, multi-field, translation, arc and patient ro-

tational techniques. Phantom studies suggest that patient rotation provides tha

best isodose uniformity, although the eight-field technique proved to be almost

as good. The six-field teohnlque provides somewhat less dosa uniformity but la

considerably better than the two- or four-field techniques. Slnoa tha human body

Is not a simple cylindrical shape, there are marked undererpnsed areas which

often require supplementary treatments. Alth tha use of rotation or multiple lar-

ge overlapping fields, tha typioal skin sparing dose buildup region disappears

dua to the obliqua incidence of many electrons, whioh results from tha curved

patient contours and multiple eleotron soattering prior to lnoldenoa on tha pa-

tient. Tha physioist and olinioian must take into aooount tha X-ray baokground

as represented by the tall of the depth dosa distribution ourvea, particularly

when high energy beams ara strongly scattered and degraded in energy so as to

produce a depth doss ourve apparently equivalent to a significantly lower energy

beam. The oumulative X-ray contamination measured at 10 on depth and averaged

over the "patient oroas seotion" for all fields typioally ranges from 1-456 of

the mean total electron doe* maximum reoeived at or near the surfaoe In the ro-

tational, six-, and eight-field teohniques. The higher number is assoolated with

highor energies, poorer beam aoattaring teohniques and with tha use of many field*.

A 4* X-ray level la considered ollnloally unsatisfaotory by many.

Aooelarator-; >duoed alaotron beams offar an attractive ionising radiation

souroa for treatment of large areas to oontrollable depths. Although megavoltage

eleotrona have a maximum penetration range of about 0.5 g.om par UeV in low Z

material, their arerag* penetration range, as expreseed by tha depth of tha 504

doee, la far lass. Several llnao-lroplemented treatment techniques Incorporate a

larga, clear plaatio aoatterer/deoelerator panel about 1 om In thiolmess and

1 m x 2 m in croaa aaotlon. It Is plaoed about 20 om in front of tha patlant and

oontrlbutaa to large-angle aoattar of the emergent eleotrons. Thla improve* doae

uniformity, particularly on obliqua body aurfaoea. Tha panel oan alao provlda

a mounting surfaoa for monitor lonlzatlon oliambera looatad olosa to tha treatment

plane. Providing good doaa uniformity over th* height ant width of a patlant

usually naoeseltatea th* "uae of larga diatanoca between aoatterer and patient,

- 40 -

typically 2-1 meters, with the dlstanoe being technique dependent. Hence, existing

treatment room layouts may restrict one a choice of TSET teohniqu*.

Narrow reotangular baeun

This section describes techniques used primarily with Van de jrsaff accelera-

tors in fiied positions with vertically downward beams, accelerator energies of

1.5 to 4.5 KsV and with patientB translated horizontally under such beans, "ince

the accelerators are in a fixed position, the patients are translated on a motor

driven oouch placed under the downward-directed beam of electrons. At Massachu-

setts Institute of Technology (.v.IT-Lahey Cllnlo Program), the elotro»s are scatte-

red by Al folio plaoed near the vacuum window of tha accelerator drift tube. They

are directed into a co«e having a slit 1 on x 45 cm oriented at right angles to

tha dlreotion of motion of tha oouoh. A gausalan distribution of dos« across tha

width is obtained with a variation of about i 10% at a transverse treatmant plan*

118 cm from the electron window. The dose varies as rauoh as - 159G, as the distan-

ce of the alcin below the cone changes during treatment.

Single horizontal beam

A single horizontal scattered eleotron beam technique employing a linao for

a stationary, standing patient has been desoribed by Tetenes and Goodwin. In or-

der to obtain e flattened beam with an eleotron energy of 4 MeV at tha treatneat

plane, an initial accelerator energy ot 6.5 MeV was used with a titanium scatte-

ring foil 0.15 mm thick plaoad 10 cm from the accelerator •Jtit window. A poly-

styrene scattering and beam-flattening filter was mountad on the front of the

treatment naad with a distance of 7 meters between the accelerator beam exit

window and the treatment plane. The measured transverse uniformity in the treat-

ment plane for this technique was - 1$ within a 40 ora radius around the central

axis and within - &% for a 200 cm diameter civcle. The maximum dose rate at th«

treatment plane with both soatterers In place was 3 Gy.mln.

Pair _of_ horizontal beams

In contrast to the long treatment distance of the single-scattered electron

beam 'ecrmi'jue described in above, iizux, e_t__al, describe a technique using two

horizontal parallel beams at a treatment distance of about 2 meters. The techni-

que was developed for an 8 MeV linear accelerator and includes the use of oar-

bon energy degraders, located Just beyond the exit window of the accelerator.

By use of different thictness carbon decelerators, tha depth of penetration mam

adjusted to m«et the requirement* of the individual oa9«. Two horizontal beans,

with an «il«l ••paratlon of 150 om, war* uatd to obtain - 5% uniformity for •

treatment plttne 200 am high. Tha I-r»y dosa w*.a about 2% of tha peak valua for

eaoh field.

Ptndul um-a.ro,

Another teonnique daaorlbad by 3awoh«nd, at. al., uaes an iaooantrlcally •oun-

tad 8 llaV linao. Tha aooalarator la rotated oontlnuoualy during traataant In m

50 arc about tha lsooantar starting from an Initial angle with tha baaa axis

aimed balow tha feet to a final anfl* almad abora tha haad of tha standing pa-

t i e n t . A o i l - f i e l d technique ie deaoribed with the total X-ray cone measured at10 cm depth equal to 4.2% of the average electron dose at D .

Patient rotation

St.idlse of treatmento involving patient rotation about a vert ical axis for to-tal nkln irradla'.ion Include the work of Tstenes and Goodwin previously c i ted andthnt of I'odgorsalc. The la t t er unee a s ingle horizontal beam with the ecatterernear th» beam exit window and a 7-meter treatment dlatanoe. With an acceleratorenergy of 6 MeV and a depth dose curve equivalent to 3.5 MeV in the treatm»ntplane, the 2-ray background amounted to 4% compared to 2-256 for the >ten*s indGoodwin method. Rotation therapy oan reduoe setup and treatment urauo and s i^ . j l i -fy beam matohing, but problems ariaing from shielding by limbs are l i t t l e affented.

Pairs of angled beams

Palra of angled electron beams, two to eight In number, are the r.ost nnnvnonlyused method of obtaining large f ie lds for total a-iin irradiation with lsooentrl -ca l ly mounted l inear accelerators . This technique i s i l lus trated In r'i>~. 1 for

Geoajetrioel arran-gement of tha ajaj••trleal dual-field trvataanttechnique. Equalexpoaurea are s i -ren with eaoh beaa.Tha oallbratlra pointdoaa la • /x-O,y.O/In tha trsataaatplant.

s ix pairs of angled beams (a l l dual - f le lde) . This geometry provides a reasonablyuniform dose distribution at tha treatment plane. The patient largely avoids the,.-ray fluence of the forward-dlreotad bean. An external soatterer la often pla-ced on the front of tha treatment head located several meters from the patient .Th* ajtia of tha beam la aimed bellow tha patient'a feet for half of tha treat -ment and above their haad for tha reaalnder. Typical beam angles with tha treat -ment plane 3 metera from tha soatterer ara - 20 . This TSET treatment techniquela described in detai l In Section 2 for tha oaae of alz pairs of angled beans( d u a l - f i e l d s ) .

- 42 -

F<g. 1b

b) Sequential two-day treatment oyola

Illustrating the angular orlratatio

of the alz dual-flelde rig. 1c

o) Pat1ant poaltlon stanoee for

tha anterior, posterior, aad

two of tha angled dual-field

exposures

2 . ii 1 x d u a l - f i e l d I r r a d i a t i o n t e o h n i q - i

n e o i n a t r y

The six dual-field teohnlque widely used with lsocentrloally mounted llnaoa

employe palra of angled beams as shown In Pig. la, with th« patient standing In

six angular orientations about a v«rtioal axis, three each on alternating days

aa shown schematically in Fig. 1b. Four of th« six patient orientations ara illu-

strated in Fig. ic. The particular combination of alx-dual fielda provides accept-

able dose uniformity and low I-ray dosa to tha patient. Although moderately coi-

plex it may be implemented on many oonteaporary isocentrlc llnaos In moderate si-

zed treatment rooms, toaimetrio characteristics of TSET beams are examined for a

single horizontal beam, a single angled dual-field beam, and the full six dual-

field beams. These parameters Include depth doaa, isodose distributions, field

flatness in the treatment plane and I-ray background.

Single horizontal bean

The characteristics of angled dual-field* oan be more easily understood by

first examining tha features of a single horizontal bean In the treatment plane,

fig. 2 shows the relative oentral axis depth-lonlzatlon curre for such a beam at

the calibration dose point of Fig. la, a treatment plane midpoint approximately

3 m distant from a soattersr plaoad on the front of the treatment head. The ener-

gy and penetration will be less for a pair of dual-angled beams. In addition, tha

avsrage penetration depth below the akin surfaoe of a patient plaoed in all six

angular treatment orientations will be signifloantly leas than this depth, par-

tloularly for an angled beam incident on lnolined body surfaoes. This la lll«a-t*ev»

tad In Fig. 2 for all twelve fields (six dual-fields).

fig. 3 Illustrates the isodose distribution In a rertioal plans through tha

oentral axla for a bean similar to that in Pig. 2, but about 1 HeV lower in ener-

-60- \

-soF

-loo!

0.15

-i!0:-i

2 tn</cm» ADDED AgSOBgE*

F1Q. 3

rig. 2Depth dosea In water for a singlehorizontal field with 6-0 and forall 12 field* /6 dual flelda/uslagfill in a nuaanold phantom/fraae, Haf.2/.

Iaodoaa dletribution in the y-a plane for x-0 and ©»0. This distribution la oon-atraeted fro* depth-dose ourvea aiailar to Tig,2. but taken at varAou* points 1 Bthe treatment plane and at a lower Incident elaotron energy.Daahed portions of theourves are aztrapolatlona. (Kaxaaark at al., Ref. 3).

gy and with a lower x-ray background, flote that the i-ray baokground of 0.5* ia

strongly peaked in the forward direction and falls rapidly for off-aiia points.

It is clear that such single fields do not adequately oover the patient's body

height, so that much longer distances or multiple beams must be used.

Dual-field bean

Two angled fields oan provide Improved dose uniformity over areas the sl«e of

patient dimensions. In thia technique, two equal exposures are given one from eaoh

of the two angled components of a dual-field as shown In Fig. 1a. The forward-

dlreoted X-ray peaka from auoh a dual-field exposure are directed above and beluw

the standing patient resulting In the X-ray baokground profile given In Pig. 4

whose average la about 0.7* for a single dual-field and about 1.5£ for the full

six dual-field irradiation (at any point, three dual-fields oontrlbute to electron

do** and «•!* to X-rays). The X-ray background may vary from one accelerator to

another for the asm beaa energy

and depends signlfloa&tly on all

Materials in the b«am. A ooaposlta

dose dletribution at the depth of

dose Baxlanm la ehown In M e . 5. 0-

niformity la within ± if orer su¥-

stantlally all of the body area la

tola plan*. Ik* angle 0 batman tfc*

horizontal and the baas central axla,

a* ahem la Tig. la, la ohosen to

prorla* ta« bast doae Tartloal anl-

Mg. 41VERTICAL DISTANCE FROV PLANE CtNTCR <cr RelatlT* z-ray baakground la the j

dlraatlaa at x-0 far a slagla a-ra-aotrlaal «aal field. i n n u M a t owara aate at a deytk af akawt 4.0g/e« * «f polyatyraaa.

- 44 -

-in I

formlty at the depth of doaa maximum aa shown InTig. 5.

Six dual-field beam*

When tha patient la placed In a l l alz positions,with a dual-flald Irradiation at ea«h position, thedapth doss 1* oonalderably laaa unlfozm than Indi-cated in Fig. 5, dna to body ourvatura, tha variedangle* of alaotron ineldanoa and tha flnlta nuaibarof baa* orientations. Tha alz patlant orientationsare apaoad at 60 degree lntarrala resulting In avariation of does that baa- a 60 degree periodloityfor a cylindrical phantom. Aa aaan In Figure 6, thlaTarlatloa la approilaately t 10* at tha eurfaee,dropping ta * 5* at a dapth of 3 aai. Tha Boat dra-matle affaat, howarar, la tha vary rapid fal l offaf doaa with dapth for tha full alx doal-flald Ir-radiation.

Fig. 5Coapaalta laodoaa diatrlhtitloa in tha i-y pla-»• t»r a-0.34 f>ai2 •olyatyraaa'. Tha twa a«a-•aaaat kaa«a mr» anglad at 1 10° and aona»-llaad to too at tha palnta /a-0, y** (0 oa/.

3 . L 1 n • o o p e r a t i n g o o n d l t l o n a

U n a o o p a r a t l p g

Thaae lnoluda naohlna paramatara iiuoh aa llnao b«aa ourrant and anargy to-gether with treatment head aettinga and poaalble maohlna nodlfloatlons. Stabla,rapaatabla llnao operating oondltlona are oeatral to satlufaotory TSBT therapy.A high average llnao beam ourrant la needed to provide an adequately high doaarata In tha patlant treatment plane (e.g., at least 25oGy.mln at Dffl . tha doaamaximum) aeveral matara dlatant. Doaa rataa of 1 Oj.mln"*or higher are dealrable-4.n order to reduoa patient treatment tinea. Beoauaa of the large invaraa aquaraIan dopendanoe and aoattarlng loaaea, the low energy eleotron mode for TSBT ty-ploally requlraa an average beam ourrant oomparable in magnitude to that for4-6 MV X-ray traatneflt. ?or aoae teohnlquee, the baa* ourrant nay ba 100 or aoratlmea than that required for enall field eleotroa therapy of oomparable anargy.

Bean fleoelaratora/aoatterara

Tha provlalon of large, uniform, low energy alaotron field* for TSBT entaliatha Interposition of materials to soattar tha beam and may require additionalmaterial to reduoa tha beam energy to a dealrad ralua. Thlok materials used pri-marily for this latter purpose ara termed "daoeleratora* or "energy dsgradera".

- 45 -

Thin materials used pri-marily to spread out thebeam are termed "neatte-rers". InterpoBsd materialboth scatters the incidentelectron beam and reducesits energy ao well as ge-nerates a contaminant me-gavoltage X-ray background.The selection and place-ment of aoatterers and .de-celerators are stronglyinfluenced by the need tominimize this backgroundradiation. All three pro-oesses occur in a givenmaterial, but their pro-portions are differentfunctions of the atomicnumber, 2, of the material,

and of beam energy. The accelerator elcotron window, and internal loniaation ohan-ber i f left in place at its normal location, function as ; artial scatterers, bution recomblrition in the high-intenaity beam may preclude the latter's use formonitoring.

Beam monitoring

- - 1>V

Percentage doae variation vi.depth In i 30 oi dia-•eter oiroular phantom.Obtained for 6 dual fieldsfrom a oiroular travene around the phantom exposedat th« l«*«l of the calibration point /S«« ttg.l/.A smooth ourre baa been drawn through data paint*whoa* rarlatiom around the phantoM Is Illustratedby the yertioal spread between the bar*.

Electron beam monitoring is an important aspeot of TSET. The parameter monito-

red Is usually the eleotron fluence rate, or the absorbed cose at L or at some

deeper point. The response of the monitor. Including associated electronic pro-

cessing devices, should, as far as possible, be direotly proportional to the pa-

rameter of Interest, ar.d the constant of proportionality should be independent

of other parameters of the beam. Monitors must be calibrated, and their calibra-

tion should remain constant over extended periods of time. Monitors for T."ET may

include the customary Internal transmission monitors located in the treatment head

or external monitors located either on its fnnt surface or near the patient

treatment plane. Stable monitoring of patient treatment-plane dose requires sta-

ble electron-beam energy and accurate reproduction of radiation-field geometry

between mojitor and patient as well as the absence of obstructing material bet-

ween monitor and patient, conditions soa>etim»s not maintained in practice. A fre-

quently uee<: combination for T5ET monitoring involves a full-beam transmission

lonization chamber at or within the treatment head and a sampling chamber or e-

lectroa colleotor placed at or near the patient treatment plane but not in line

with the patient. Aotivatlon of a sampling monitoi can be incorporated in the in-

terlock chain for TSET and give notloe of the absenoe of an eleotron applicator.

Many centers employ a baokup timer te limit the maximum treatment time.

All beam monitoring systeaa require. thn.t e. prescribed doae at sow* relevant

site or plane be unambiguously and repeatably related to a Monitor Unit (,7V; v«-

lue read out on the control oonaole. Satisfying this requirement for T.TET can t>e

more difficult than for conventional X-ray and eleotron therapy. Beam monitoring

for TSET is significantly more oomplex and unoertain than for oonrentlonal X-ray

and eleotron modalities. Redundance la essential in order to proteot the patient

- 46 -

from the iitrimt r**ult of failure of th« Integrating do** monitor. Suoh factor*

as tlia l*.r«e lln»o beam currant, th« large 33D valuta, th* Interposition of on*

or mor* diaorot* soatterer*, th* effeot of air aoattarlng and variation* In pa-

tlent-maohlne poaitlonlng combina to lntroduoe largar variation* In oallbratlos

stability. Typlomlly than, between tha patlsnt treatment plan* and the Internal

llnao Ion chamber, an Inverse aquare do** raduotlon of the order of 100 or more

time* oorabines with a reduction du* to scattering of 10 to 100 tide* yielding an

overall dose reduotlon that may be significantly greater than 10 . It la th* oon-

ntanoy of this faotor that ensures stable and aoourata doslm*try. This larg* fao-

tor gives added signiflc&no* to th* reoommendatlon that beam monitors be plaoed

distal to beam-modifying oomponent*. It may b* feasibl* to monitor the field at

the treatment plane and to Integrate the eutput of suoh distal and for TSET, di-

Btant monitors dir*otly Into th* oon*ol*-do«* r*ad-out system.

4. b o s l m e t r j a n d I n s t r u m e n t a t i o n

boslmetry for TSET is difficult and c jmplex beoausa of the n*ed to measure

and evaluate absorbed do** at shallow depth* over a large area In the patient

treatment plane. Many radiation deteotor* ar* too thlolc for these high-gradient

depth do** field* or exhibit algnlfloant variation* In direotional response.

methods,

The deteotors suitable for this T3BT inolud* lonleation ohambara, film, thermo-

lui:iln»nc»nt materials, Frlolc* dosimeters and ?arafiay oups. It Is Imperative to

Rjiovr in detail how each funotlona so that advantage oan be taken of th* special

fentures of each. For scanning in a water phantom, small thimble ion chambers,

with well-studied polarity and saturation «ff*ots, ar* needed. They- should have

air volumes with linear dimensions of a few millimeters or lass. Small-volume, pa-

rallel-plate ionization chambers having a thin window and shallow active depth

(about 1 mm) are advantageous for depth-dose acquisition In a flat solid phantoa.

Semiconductor diode detectors, If proven reliable when compared dlreotly with small

Ion oharaber* In aimllar eleotron beam*, oan b* useful for measurements with good

•patlal resolution. Film o&n provide data over larg* areas rapidly but 1* subjeot

to error. TLIJ ohlp*, oube* and wafer* ar* valuable, but their aoouraoy must b* con-

firmed agalnat Ion ohamber data, and their anl*otropy for low enargy electron* must

be studied.

Doslmetrv phantoms

Sine* no aolld material mimloa tlsau* pr*ol**ly with respeot to energy XOM» and

soatter, *om* water phantom depth-dose data ar* usually obtained a* a r*f*r*noe.

Polystyrene, whioh ha* an eleotron density very olos* to that of tlasu*, la th*

moat suitable material tor a solid phantom. Lay*r*d, flat phantoms ar* raployad

for obtaining depth do** and build-up data, but cylindrical phantoms of appropria-

te radii ar* u**ful for simulating patient body and lla* croa* **otlon*. If film

la u**d, oar* should b* taken t* eliminate even th* *mall**t air g*>pa when *l*o-

trona traver** It at or u*ar grating inoldenoe.

- 47 -

DoBimetn/ measurements

A wide variety of dosircetric measurements must be carried out in rtevel ping

e 1'SET technique. These include electron energy, fluence, depth dose,' and loodo-

se measurements. Absorbed dose measurements art described in a later section.

The electron beam incident on the eiit window of the accelerator can be characte-

rized by a relatively narrow distribution of energy fluenoe whose peak is termed

the accelerator energy, Ea. Before raaohing the patient treatment plane, the e-

leetron beam is scattered and further spread out and degraded in energy by pa-

ssing through a sequenoe of materials consiatlng of the exit window, scattering

foils, monitor ohambers, perhaps the field Illumination mirror and additional

deoeleratora (used mainly to rsduoe the beam energy and penetration) and Inter-

vening air. For TSET, the average energy loss occurring In thla aequenoe la ty-

ploally 1-2 MeV but may be higher if deoeleratora are employed.

The moat probable energy. K_ „ In MeV, Is defined by the Harlcua range-energyp,o

equation where R_ is the praotioal range In om of water:

EpEp,o " ( V

The msan energy at the treatment plane, Eo in MeV, is defined In terma of the

absorbed dose at the half-value depth, Hj0, in om of water:

I, - 2.3J R5Q

It is reoommended that the most probable energy, E o, as defined by the Mar-

Icus equation for a single horizontal beam, be employed for specifying dept.1 dose

and lsodoae curves as well as for energy specification of the electron beam at

the treatment plane. In addition, it is reoommended that the mean electron energy,

E , at the half-value depth, R, , be employed for dosimetry of energy dependent

calibration faotors in oaloulating absorbed dufle.

iepth dose data can be aoqulred with a parallel plate loniration chamber over-

laid with varying thicknesses of polystyrene absorber. A s-all amount of rolysty-

rene surrounding the chamber suffioes for this measurement. It has been and use-

ful to erect a plywood panel with a ooordinate grid juBt baclc of the pati;nt treat-

ment (x-y) plane and to provide a method of positioning the chamber with absorbers

at defined points in the treatment plane ualng the coordinates of the grid (Fig.1a).

Radiation field uniformity assessment and construction of tsodose patterns at re-

levant depths, z, beyond the treatment plane, can bo achieved by combining depth-

dose data from an appropriate selection of points in the (x, y) field for each

absorber thickness.

Multiple-field measurements

Several oentera have examined the effeotp on dose distribution of combining

various numbers and oonfigurations of treatment fields ualng oyllndrloal and other

shaped phantoms. Many aleetrons entering the skin surfaoe are inoldent at large

angles from the normal to the treatment plane, and the akla surfaoe itself la of-

ten al,jnifioantly ourved and oblique to thl» plane. Aa a oonsequenoe, dose dletrl-

butlcao over the patient'a akin vary widely, the relative simplicity of small field

doaa dietrlbutlone la loat and no alaple uener*li*atlona are applicable. However,

alnoe the radiua of ourrature of moat eurfaoe anatomy la large oompared to the ran-

ge of TSBT eleetross, the depth, doae normal to the aurfaoe la determined to a lar-

- 48 -

ge extent by the angle between the inoident electron path and the normal to the

•kin eurfaoe. Composite depth dose and ieodoae ourren oan be constructed and esti-

mated by applying this prlnolple to the oontributlng field* »ni then aumming and

normalielng them. BJarngard, e_t§l., hare atud.ied depth doee at rarloua anglite of

inoldenoe for elngle and multiple fields at 4 iind 7 MeV for 15 and 30 om diameter

circular pnantoms as well as with nnthropomorphlo phantoms, at three meters di-

stance.

Absorbed doae measurement

It is recommended that TSET absorbed doso be evaluated at the calibration point

located at (0,0,E) as defined in Fig. 1a. Thin is to be carried out using the

Bragg-Graj type procedure described in AAPM TG 21 protoool using data for 5 MeV

electrons. Data for energies below 5 MeV may be found in ICRU 35. A polystyrene

parallel-plate ionlzation chamber having an established K B value is used in a

polystyrene phantom. The proximal surfaoe of the cavity is to be placed at the

depth of dose maximum using overlying polystyrene. Usually, the dose maximum occurs

on the phantom surfaoe and no added overlying polystyrene is needed. A single dual-

field exposure is employed with the beam axis dlreoted above and below the center

of the ohamber. The calibration point dose is related to the treatment skin doae,

defined below, by a constant faotor for the particular treatment technique employed.

Treatment Bkln doae

Patient and radiation field asymmetries result in a complicated variation In

doae to local anatomical areas. To simplify the calibration procedure and to faci-

litate comparability between institutions, the treatment skin dose is defined as

the doae to a cylindrical polystyrene phantom 30 cm in diameter and 3C cm high

which has been Irradiated as a hypothetical patient. The oylinder Is exposed with

its proximal surface placed in the treatment plane and with its cylindrical axis

vertical and placed so that its vertical surfaoe midpoint coinoldea with the oali-

bration point (i • 0, y • 0), as defined in Pig. 1a. The treatment skin doae is

then defined as the average dose at E m a s evaluated for a circular traverse around

the phantom mid-circumfarenoe when exposed to all six dual-fields. D m a x for thia

six dual-field exposure is usually at the surfaoe.

Precautions and routine cheaks

A number of precautions and routine check! can serve to establish confidenct in

the TSET technique and ensure safety in carrying it out. Many items will be part

of an ongoing Quality Aosuranoe program.

It Is strongly reoommended that a local written procedure be provided for chan-

ging from conventional modalities to TSET and vice versa. This written procedure

should be as simple as possible and conveniently available at the oonaole. The

technologists and physicists involved with TSET should be thoroughly faailiar with

the chnngeever precedure and cegnicant ef abneraal eperating canditiana Defer* ini-

tiating treatment. The change-ever precedure itself, which will depend an lacal cen-

ditiena, shauld ba unaabigueua end aheuld previaa adequate eafety interlace canfir-

nstian end precedurel checka. It sheul* lend itaalf ta r*»i« exaeutian, preferable

taking five Minutes ar less ta c*rry eut. The treatment unit shauld ba "run up'

prier te treatment ta vei ify nermel eperating ppraaetera and awniter eparatian.

- 49 -

Th« extent ef participation «f the reapaneibla physicist in the chenge-OTer

will vary f:•• center ta center bnd is a Batter af judgnent. It dependa uaen the

technique •elected, the equipaent available ta oarry it eut, a one danger ef a pa-

tient falling during the ceurae ef a treatment, the room eheuld be squipsed *ith

a pan-and-tilt type of TV caaera far constant aenitering. The patient aheuld be

instructed and snceureged te signal when a need fer a rest period is felt.

Typically, a daily TSET session ef three dual-field treatnents requirea 20-25

ninutes af facility tlae. Althsugh « daily dase ef 100 eOy at a daee rate ef 25

cOy. Bin invelrea enly 12 sin af bsaa-en tiae, the eequential patient uni Machine

aet up precedurea *r* tine ceneuaing. Dase rates af 100 er aere cGy.ain ara de-

sirable in reducing treatment tiaes.

The skin ef arny pntienta having whale body irradiation is very suaoeptlbl*

tc being daB'ged by sersping and bruising. As s result, attentlen eheuld be given

te tilininating shf-ra edgea that can ceae in centaet with the pstient er tht>t they

aay fall againet. Since the sales af the feat eften hare cracked and bleeding le-

sisns, it is spprapriata te supply diapesable bath aats far walking and atending

er, nltemntively, dispeesble slippers.

If there is any type ef a "cage" in which the patisnt stsnda, especially a part-

able ene, it aheuli be attached securely te the wall er fleer te prevent tipping.

Depending en the patient peaitiening, overhead, atraps far the hands asy be requi-

red and aeae neana will be needed fer auppert ef the atrape. Ta allew fer faatar

peaitiening, fleer teaplatae can be uaed te indicate tha plrceaent ef the feet.

fitlent shielding

Th» laria ef the ey*a will gonernlly be shielded. Other bedy parts ouch us the

rih£«r noils end tae naila aay be shielded b,y ahaped sheet lead when theea pet—

tlana af the anateay can bs safsly eicluded fre« the treataent. Depend Ing en cli-

nical involvement end technique, shields fsr the hands er f«et Buy be provided.

One Bheuld be swsrs ef the lnereaaei deaa te the Inner surface ef the eyelid,

aa large ea bC%, frea the berkscr>tter ef the internal high-Z lead aye shield.

When ehielding parta ef the anrteay, the ahlalda aheuld be placed near the patient,

rather than at the naohine calllaater. The projected light-field edge is nst useble

fer defining the cuter edges sf the rnMatlen field ht theae extended distances.

Internal eye shields ere 'vallable oeaaercially but can be aada if facilities

are available, aa suggsstsd by Praass. A ceaaenly uaad thickness st 4 HaT is 2.0

BB ef lead. Ceaaercial ays shields asy provide BTglnsl shielding, depending an

the incident electron energy. Eye shields used internally cannot bs axde as thick

»m sne would prefer. They ara likely to offer lass protection near the edges where

they are thinner, and the traneaiasisn there can be in the range ef 15* or 25%.

If • tab is provided ta asks inssrtisn sssisr, there will be considerably greater

thickness sf lssd st the center. When the pr-tient stands, the eye shields hero a

tendency te ells downward. If the ays shields have sufficiently long trbs, a pise*

sf fsbric with a silt fsr the tab sf the eye shield, together with a Volere head

• trap, can Us unsd effectively t« ksss the aya slilsll cantered.

Lscal beset fields

The extent sf the ores ef the beast fields needed will require clinical judg-

ment frea the radiotherapist based en the underdosed regions resulting froa 7SJTT

treataenta. These will net be clearly defined regions, as a rale. The areaa gene-

rally beestsd will bs the solas sf the feet, perineal area, the akin in the peri-

- 50 -

anal region, and the infrananaar; region in feaalee with large braaata. In tha la-tter ease, the uea af a thin braaaiara during treatment a*y elialn*te the need farbaaat in that radian. In addition, beeet fialda have baan ceneldered neoeesery fe*the tea ef the bead »nd tha ear canal in aaaia aituatiana. Beeat fields *re pro-vide*either v»' th snail field rlectrena »r ertheveltege X-raye at customary S.iD'e.

In viva doac measurements

In viva desiaetry neasuranenta are inpartant far TSET therapy far twe reaoeno:1/ determination af tha distribution af rteoe ta the patient's akin, and 2/ verify-ing that the prescribed daaa ta the patient'a skin ia cerrect. Meaaoreaent af thadose und the deae distribution with a saell phentea at tha patient treatment pe-aitian have been described in several publications. Xha actual miiferaity af thadose delivered ta tha patient'a akin, hewever, asy vsry significantly fraai that"in-air", ne that asaeuraaent af tha actual akin daaa distribution ia re^uirwJ.

Several types af daaaaetara n»y be considered far uaa in these •eaaureaenta,including snaH ianitatian ch^abera, diodes, f i la , and araaa which ahauld be • * • -surod an each pntient /at least 40 i f ana ia investigating a new technique/, ianchanbers and diadaa becaaa lapraotleal. Tha uaa ef f i la la reasonable, eltheugha rather large nuaber af sanll f i la packata ar large sheets or atripa ef f i laauat be uae4 to obtain tha requisite data. Sine* the f i la and i ts lightproof pack-aging are rather thick, ana Bust be concerned about paaslbla interference withthe dese th»t tha patient's skin receivea. Theraeluaineeeent dosiaetera, therefore,are the logical choice far in Tire dosiaetry far theaa la* enerfy electron fieKa.

A large nuaber ef skin-daaa aeasureaenta have bean reported by Fraaos and Palaauaing the aix dual-field technique. The resulte are indicative ef the reaulta taba expected fraa exaainntian af athar traataant techniques. The daaa ta varieuaparta of tha cheat and PMMMI varies only a faw percent, aa predicted by tha"In-air" dasa distribution. However, far aany athar parta af tha body, the aeaau'-rad akin deeea are aaro than 20ft different fraa tha daaa ta tha antariar af ther-bdeaen /the reference paint/. In particular, Beet parta af tha feat and ankle,except the arch, receive between 10* and 23% as re daaa than tha reference point,aa da the eara, neae, and fingers. Many araaa race ire at leaat 20% leaa deoe thanthe reference point, including tha forehead and scalp, wrist and pals, axi l la, e l -bow, and nedial thigh. The a"gniiufle of noat of theee nonuniforaitiee does not va-ry nuch from patient-to-patient, suggesting that ths variations are technique de-pendent, rather thrn dependant on tha individual patiant snatoay.

References

1. iMPM Report: Total Skin electron Therapy: Technique and Dosiawtry, In Preee,1986.

2. Aeboll, S.O., Siu, J . , Lightfoot, D.A., Brady, L.W.: Individual!tad aye ehieldafor uae in electron beam therapy as wall as low-energy photon irradiation. int.J.Rediat.Oncol.Biol.Phys._£i 519-521, 1980.

3. Bjfernfnra, B.B., Chan, Q.T.r., Piontek, K.W., Svensaon, O.K.: An^lyaia ofdose distributions in whole body superficial electron therapy. Int.J.Rad.iat.Oncol.Biol.Phyo. £: J19-J24, 1977.

4. Coffey II, C.W., Maruyana, Y., Stewart, B.L-, Write, O.A.: Electron beaa irra-diation for raycoeis fungoidas uaing variable energy. Reprinted froc tha Journal oftha Kentucky Medical Association, 7 pagee, July, 1982.

5. Edalatein, O.P., Clark, T., Holt, J.O.: DMlaatST tor total-body electron-

- 51 -

baa* therapy in the treatment of mycosis fun*oide». Radiology 10£: 691-694, 1973.

6. Frfieae, B.A. , Roberaon, P .L . , G l a t e t e i n , E. : Whcle akin e l e c t r o n t - e e t n e n t :Pa t i en t akin dose d i s t r i b u t i o n , Radiology 146: 811-814 , 1983.

7. l i a y b i t t l e , J . L . : A 24 cur i e strontium 90 uni t for whole-body aur<>rficiali r r a d i a t i o n with beta raya. Br. J . Padlo l . XL- 297-301, 1964.

8 . Hol t , J . G . , Parry, D .J . : Some physical conaHerat iona in whole o i ir . e l e c -tron bean, therspy. Had. Phya. 9.: 769-776, 1982.

9. Jackaon, S.l l . : The c l i n i c a l a p p l i c a t i o n of e l e c t r o n bean therapy with e r e r -f l e a up to 1C II«V. Br .J .Radlo l . £ } : 431-440, 1970.

10 . Karzx'irk, C .J . , I oaring* r, P . , S t e e l e , R.S. , WelaaMuth, H. : A tartr.i ;u«for l a r p e - f i e l d , aupcrf I c i a l a lae tron tharary. Fadiolo/ny 7_±; 6} 3-644, I960 .

1 1 . Kumar, P . P . , P a t e ] , I . S . : Comp«rieon of does d i a t r i t u t i n n with d i f f e r e n tt e r h n l i u e e of t o t a l akin e l e c t r o n baaa therapy. C l i n i c a l Radiol . ±±: 4?t-4Q -T,19B2.

12 . Hiroomand-Pad, A. , O i l l a n , M.T., Konmkl, K., Kl ine , P.W. «nd Oriirir, D .F . :toae d i a t r i b u t i o n in t o t a l »Hn e l e c t r o n beam i r r a d i a t i o n ueinp the n i x - f i e l dtec t -n i iue . Tnt. J . H#"Hat. Cncol. I ' io l . Tr.y». l£: 4]r>-419, 19P*>.

1 ) . Ta,-«, v . , Gardner, A. , Karrtnark, r.J.: Patient rfnaimetry in • t <• a l a o t r o *'iaat».i«i.i «f lar«« s u p e r f i c i a l l aa iona . fad lohlolo/or, JJ^: 6 )^-641 , ''• \ .

14. Porter,reak, B.b. , Pla C , Pla, M., l.efetnrre, P . I . , l iesae , P, : H.ysii-aX • • -perta of * r o l a ' i o n a l t o t a l akin e l e c t r o n i r n . d i a t i o n . Ked. Phya. l£: ]->9-lfcP,1 1 I M .

IV. ..ewct'«nd, * . , Khan, P.M., Wil l iamaon, J . : Tot '1-body a u p e r f i c l a l e l e r t r o r -bmT il e r a . y u«in« a m u l t i p l e - f i e l d perdulun-erc t e c h n i o u e . PndioloRy. 1 JO: 49J-4 9 8 , 1^79.

16 . J i s f ' a l , I I . I . , Johnston , D.O. , S a l i n a n , F . A . , Trump, J .O. , Wripht, K.A.:Tfn y e « r e x p e r i e n c e with low megavolt e l e c t r o n therapy. Am. J . Poent^-erol . hf--

-'iurr Ddr^pj- Nuclear Med. t e : 21i>-2<?8, 196C.

i ' . j i u r , L . , S i l r e s ' - e r , J . A . , EJewley, D.K.: Treatment of the whole tody eur-fnce wi th e l e c t r o n s . The Lancet , pp. 1373-1377 , June 1962 .

I P . T e t e n e s , P . J . , Ooodwin, P .N. : Compi.ratiTe study of s u p e r f i c i a l whole-bodyr a d i o t h e r a p e u t i c t echn iques u s i n g a 4-MaV nonan^ulated, e l e c t r o n bean. Padiolojrjr.1 2 j : 2 1 9 - . V 6 , 1977 .

1 9 . Trump, J . U . , Wright , K.A. , Bvana, W.W., Anaon, J . H . , Kara, F . F . , fromer,J . L . , Jacqua, G., H o m e , K.W.: Hlph energy e l e c t r o n a f o r the traatment of a x t e n -alve euperfIcial malignant lesions. Am. J. Poentgenol., Radium Thernpy NurlsarMad. §2: 623-629, 1953.

?0. Williame, P.C., Hunter, R.D., Jackaon, S.M.: Whole body electron therapyin mycoala fun^oldaa- -a successful tranalational technique achiered by modifi-cation of an established linear accelerator. Br. J. Radiol. •£: 302-307, 1979.

- 52 »

COMPARISON 0? ISQDOSg CHARTS

FOR COBALT-60 TELETKZRA3Y UKIT "HOCUS"

V.Psnohev, B.Constantlnov, K.Ivanova,

Inatitut* of Rosntganology «nd Radloblology,

iladloal Aoadavy, Sofia, Bulgaria

Th* praoision of tha baslo dosimstrlo lnfoxnatloc la an essential requirement

for th« accurate patient'a absorbed dos* oaloulatlon. The traataent planning la

dona using laodos* oharta specifying tha single beak doaa distribution In a hoao-

geneous mediua. Tha plotting ot thaaa oharta la a dlffioult and a responsible ax-

perlmental taak, muoh tine-ooneiunlng If It la not automated.

Tha laboratory ot Clinical Do*imetry and Ionising Radiation Metrology (SSDI»-

Sofia) deoldad to ooapar* and oaaolc tha aoouraoy of lsodoaa oharta for tha Co

toletharapy unit "Roous", usad In Bulgaria. Tha charts ara for two source-surf a-

oa dlstanoee (SSD)i 60 and 75 oa. Tbosa for SSD 60 on ara suppllsd bj tha tnanu-

faoturer In nn atlas lssuad In 1968. Tha atlas oonslsts of 45 laortosa charts for

26 flald slaas from 4x4 to 12x20 oa2 dlaphraga divisions. It Is based on aeaaora-

aenta nad* in a solid tissu*-*quival*nt phantoa. A oondansar dossastar DIC (lonl-

satlosi chambar Toluaa 2.7 ea 3), a dossastar DIM-60 (ohaabsr rolua* 0.5 oa3) aa<

a aolntlllatlon dosaaatar SZS-1 with a arystal ZnS(Ag) - 4x4 aa war* us*«. Tha

doss distribution alon^ tha osatral axla la aeaauxad with tha dossaatar DIC and

th* distribution In th* beaa's prlnolpal plan*« - with th* saallar d*t*otors. Th*

authors of th* atlaa auggast that th* or*rail uncertainty of th* laodoae oharta

doss not exceed i 10*.

The charts for SSD 75 om are measured in our Laboratory In 1968 In a water

phantom (30x30x30 o*p)and an lonlzation ohambar type 37498 with volume 0.1 cm

of the Unlrersal Dosemetar "Philips". Tha plotting of the charts Is aade using

the decrement lines method.

The lnodose oharts made at the Onoologioal Institute, Leningrad, for 3SD» 60

and 75 om ara also included in th* oomparlson. These charts are construe.*d using

measurement* data in a water phantoa (30x30x40oar ) with the Philips doe t*t*r Ion

chamber of the same typ* as mantion«d ftbOT*.

The present measurements are mad* with a Radiation Field Analyser "Theradoa"

RPA-3-50 and an Ion chamber type VA-K-251 (Uassalelelrtronlk, GDR) witk dimension*:

diaaeter 5.5x6 on and volume 0.05 oa . 69 isodos* charts for both SSDs (60 and 75

oa)for 39 field air.es froa 4x4 to 20x20 oa dlaphraga dlTlslona are aad*. Central

axis depth dose curves for eaoh field, as wall a.s dose profiles at various depths,

are plotted. Th* iaodos* chart plotting uncertainty la of th* order of - K of

the dos* maximum valu*. Th* aoouraoy of th* isodos* oharts was checked for aost

of the field sizes bj aeasureoents of the dos* distribution along th* beaa axia

in a water phantom (30x30x30 ow?) at 2.5 oa stsps In depth with a secondary stan-

dard do9*m*t*r Paraer 2570 and ion ohambsr type 2571. These aeasur*aent« oolnel-

d* very wall with tha oharts made with the dos* analyiar, as w*ll as with th*

published data. There la also very good agreement between th* n*w oharts and tho-

se mad* by us previously for SSD 75 oa. Isodos* oharta In th* two prinoipal pla-

ne a of the 6x15 oa2 field w*r* ooaparad. Th* aaxlaal deviations ara of th* orfar

of 2 - 3 an, whloh Is aocaptabl*.

Th* laodos* oharts aad* at th* I<*nln.-rad Institute for SSD 75 oa oolnoid* wits

an aoouraoy of 1* along th* esntral axis with th* published data and with our

aeasureaents. How*v*r, taken aa a whol*, th* isodos* plat*aux arc narrower oost-

parad to thos* plott*d by us, espeolally at th* 90% isodoss curv*. Th* ooaparl-

son of th* oharts for SSS 60 oa field •!•• 10 z 10 oa' showed th* saa* diff*r*oo«a

- 53 -

In the ahape of th« laodoaa ourrea, but In thla oaa* the dlfferenoaa along theoentral ray may reach 2#.

As regards the isodoaa oharta of tha manufacturer*• atlas, tha oomparlaoniihowa significant differenoea. Tha laodoaaa plottad by us until 10-12 oa dapthaara daapar and their plateaux are wider. Tha two aerlea of beam azla dooe distri-bution measurementa aa wall aa tha published data corroborate the greater laodo-ae depth obtained by ua. On tha next two alidaa tha atlaa oharta (blaok onaa)ara oompared to ours, plottad with the doaa analysar (red ones). On tha flrat all-da tha field la 9x10 oa2 dlaphraga dlriaionn (4x6 oa2, ilde 4 oa) and an tha ae-oond one - 10x20 oa dlrialone (8x16 oa , aide 8 oa).

The differenoaa between the published depth doao diita and thoaa read froa theAtlaa were found aa soon aa the Atlaa waa rftoelrad. Tha eraluatlon of tha poaal-bllltlea of our laboratory to Bake a naw atlaa at that tiaa lead to tha decleionto uaa the manufacturer's one. In order to oonpenaate partially tha unoerteintiea,tha percent depth doaaa at 5 oa depth for eaoh field hare been read directly froathe oorreapondlng charts and thoaa data hare been uaad by tha oallbratlon of allRooua unite In tha oountry.

On tha baala of thla ooaparlaon tha following oonolualona aay ba reaohedi- The laodoaa oharta for 9SS 75 oa uaad la our oountry till now ara eufflolent-

ly aoourate and their use aay eontlnua.- Tha oharta for 8SD 60 oa plottad with tha doaa analyser ahow that tha alngla

beam doae diatrlbutlona of the unit "Eooua" ara batter than thaaa represented 1 Blta atlaa. Tha doaa (radiant In tha penuabra region la steeper, tha laodoaa pla-teaux ara flatter and la tha region laportant for tha radiotherapy the laodoeeeara at greater deptha. That la why at 880 60 oa tha saw laodose oharta are to eeuaad.

0> PHOTO! ODTPOT TACTORJ

FOR 60CO MACHINES

K.Tobola, P.Hambalek,Radiotherapy Departaant of tha Regional Hoapltal, Oatrara,J.HoTotni, I.Korar, R.Wagner, P.Jiroueek, 'Institute of Radiation Doelaetry,Oaeohoelorak Academy of Selenoea, Prague

I. Introduction

The Co maohlnea are still tha aoatly uaod aeana to supply photon beau ooa-aonly employed for the treataent of oanoar In aany oountrles of tha world. Theyara widely uaad eren In aaall radiotherapy oantrea or looal hoapltala. WhaneTera new maohlna la inetalled tha atrong requlreaenta ariaea for estlaatlon of boaaparaaatara neoeeeary for doaa planning. In addition the equipaent must fulfil oar-tain apeoifloatlone when It la taken Into uaa and during all lta future operationla radiation treataent/"l/'.

Tha treatment planning prooedure for aa lndiridual patient auat 'oa performedrery qulokly ao It la lapoaalble to get phyaloal data by aoaa meaeureaeat durlagtha treatment planning ltaelf. Oa the other hand It la really difficult to for*-

- 54 -

••• every desire of radiotherapists end to provide all these data la advance re-gardless to th» faot that suoh aa effort would l«ad to an unreasonable amount ofgained data. Bealdea that, all doaimetrlo data should be azpreaaed not only bya alngle ralue, but always an uncertainty at a oertaln oonfldenoe level must toestated. Without knowing anything about relation among the data aoquired under va-rious Irradiation oondltions every measurement amat be repeated several times toestimate uncertainty at a oertaln oonfidenoe level. This will leaA to a largeamount of data to be measured.

•Therefore we have tried to find a semlempirieal, but theoratloally w«U.founded model to express free parameters whloh oould be fitted to experimentaldata of specified oobalt units. Using suoh a model one oan manage with a minimi-sed pattern of measurement as ita results should be with a oertals probabilitypredloted by the model. This approach will provide the user more general Infor-mation from relatively small amount of measurements. Although the values of freeparameters were found only for Ohlrana's oobalt maohlne, the approach la gene-ral and may be used for any other oommeroially available equipment.

XXm Beam geometry Parameters

It la a matter of faot that the exposure rate in any point on the oentral raydepends on the oolllmator set-up. This set-up Is usually la toe shape of a tra»-oated pyramids, the upper basis is formed by the front surface of the source amithe bottom basis is limited by the distant edges of the last diaphragm, iet ussuppose the oollimator la oontlauously adjustable and all shielding blooka ordiaphragms touch only on* ray emitted from the extreme vide point of the seuree(see Tig. D . It is most convenient to define the variable oolllmater pyramid*

PC

..*._. |

?_ J

by twins of angles f ft and f^ and by a souree diameter », the upper basis ofthe pyramlde. (The souroe diameter was ooastaa* for rll mmohlaas Investigate*).This definition of the eolllaater set-«y Is laiesaadeat en the souree-volat efmesurement dlstaaee.

For the definitloa «f relatiem betweem field slae ( W ) and oelllmater anglea

- 55 -

it ia uaeful to introduee a geoaetrioal term "full light field alae". Plaid aliala uaad her* in ita usual meaning l.a. aa a multiple of two sldaa of th« reotan-gular field. Both aldaa & and b. ara dafiaad aa a gaoaetrloal projootlon of thebcaa on a plan* parpandioular to tha oantral ray (aaa Tig. 1). Let ua hare furthar£ and £ aldaa of a raotangular full light flald on tha aaaa plan* from whl h thawhola front aurfaoe of tha aouroa oan ba aaen. Tha full light alda oan ba .aleu-latad from tha propar flald alia by tha ralatlom

A . a - f.( SSD/SDDm - 1) and B - b - P.( SSD/SDD^ - 1) (1)

P danotaa tha aouroa diameter and SDS la tha aouroe-dlaphragm dlatano^. Than fortha oolllmator angla /one oan derire tha ralatlonai

r a . Jartgy>b . 2artg [(B/2 -

GoDatlnaa, aa it ia In Chirana oobalt maehlnec, tha aouroe-dlaphraga diatanoe ra-luea ara not tha aaae for both aidea a, and £ and they differ froa eaoh other intha thlokneaa of the last diaphragm. Thla diffarenoe entera ooneequently alao in-to tha definition of full light field alia relation (1). Aa It ia not alwaya ooa-renlent to bind % and £ notation to the oonatruotlon detail a of the oolliaetorayatea, a alapllfioatlon nay ba lntroduoed, without being algnlfloantly inoorreot,ualng effeotlre SDD #^ lnataad of SDD^ and SDI^. Thla figure la defined by the re-lation i

SDD#f - (2.BVDm.SW^) / (8DDa + SDDb) (3)

(8DDtf . 43.7 oa for Chlaobalt and Chlaoatat Chirana 6 0 c o •aohinaa). Than tha

full light aide la equivalent to the arlthaetloal aean of two aet-upa aade by theproxlaal or diatal pair of the diaphragm.

A - a - V . (SSD/SDD-f - 1) - (A, + A 2) / 2

where

A1 - a - P . (SSD/SDDp - 1) (4)

A 2 - a - P . (SSD/SDDj - 1)

where 3DD and BVT>i ara aouroa-proxiaal or diatal dlaphraga diatanoe raapeotlTely.A furthar alapllfloatlon oan be aade by ualng Starling'a approziaatiom

C . (2.A.B) / (A + B) (5)

whioh waa experimentally oheoked by meaauramenta of axpoaure rate for differentoolllmator aat-upa. Haxlmua diffarenoea obaerred were within - 1.5 % at the oon-fldenoe lerel of 92*.

Ualng theee alaplifioatlona ona oaa for any reotangular aolllaator eat-up j,£ derlre a aIngle ralue of oolllaater angler

/- 2artg

KJtf PfPIB^*110* ai *n* axpoaura output factor on SSI

Although only amall differenoea fro* the aiapla lnverae a«aar« lm> and oorreo-tlon fcr photon attenuation la air appeara to be la tha dependence of the expoav-re rate om the aouroe diatanoe, they hare prorea te ba ayateaatie and reproduoik-1« enough to ba taken into aoeount. Being platted tats* differences are alwaya of

- 56 -

the sane shape as it Is dooaaented In fig. 2.

a15

0.95

W.g. 2Dependenoe oftb« exposureoutput faotoron SSD

0.5distance

1.5

As aneJ.yti.oal expression, considering attenuation and scattering of photons Inthe souroe, oolllmator system and air, was proposed In the form

- H.expL -/* /(SSD+A) 2 - Fs (7)

Using Oauss-Newton's iterative nethod for the non-linear fitting, the parameters

/( , 4 , and S were found for atandard oolllmator set-up ¥ » 76.92 mrad (I.e. field

site 10 . 10 em at S3D 80 oa) and source diameter P • 21 ma to be // • 0.013 -

0.006 a"1, Am -0.0045 - 0.0018 a and S - 1.007824. The values of the exposure ra-

te referred to the exposure yield satisfy the relation (7) in the interval of dls-

tenoe SSD from 0.6 to 1.85 m with the ooeffioient of correlation of ^ 0 . 9 5 . Pa-

raaeter /f may be Interpreted as an effeotive ooeffioient of attenuation and soat-

tering of both primary and seoondary photons in air while the negative value of

parameter A reflects the faot that the oolliaator aots as an virtual souroe of

soattered photons. The third parameter I is a normalising oonstant. The value of

the mean standard deviation of the regression ourve (7) is less than 0.5 %•

TV. Cenendenoe at azDOiurt outnut factor on M**** ancle

It is a well-known faot that exposure rate significantly laoreases with In-creasing field slse, i.e. with the ohange of the oolliaator set-up. When the 41-stanee dependenoe has been oorreoted by means of the eq. (7) all Measured valuesof exposure rate follow olosely a saturation type ourve (see Tic 3)> *o« oolll-•ator angle on the ordinate was oaleulated aoeordlng to ee. (<). The ourve laJig. 3 was fitted by the equationt

- >1 - *2 • «P("b3(8)

Using agaia tke Oauss-fewtoa's aetk«4 for fitting saraaeters t^, sa «sji b« •• tkeaeasured ourve for Ohirana's oobalt aaehiaes, valves of paraaeter* •1 • 1.03*98*0.00007S, Bj.0.09302*0.000079 aw! -(0.01348*0.000028). 103 were fouad, whea tae

- 57 -

relative output8

§

ourra In fig. 3 ia noraallaadto laral on* for rafarranoa ra-lua of th« oollimator aat-upf • 76.92 mr»d. In tha int«r-

ral for y froa -8.3 to 254 Bradtha moan atandard darlatlon ofth* axparlmantal valuaa waa laaathan 0.9% (ooafflolant of mul-tlpla oorralatloa waa aqual to.995). It ohould ba notad thatall maaaurad data avaluatad Inordar to azpraaa tha oolllnationdapandanoa hara l>aan galnad foraouroa diatanoaa in tha rang*'froa 0.6 to 1.8 a and an oppoai-ta wall or a floor waa at laaat0.5 a far from tha point of aaa-auraaant.

Fig. 3Dapandanoa of tha axpoaura out-put faotor on oollitnator anglafor Chlrana Co aaohlnaa

V. Dapandanoa of dona output factor

Tha traetnant planning In radlotharapj dapanda on tha aoourao* of tha datar-alnatlon of aoaorbad doaa In watar or tlaaua. Thara ara. In ganaral, two poaal-bllltlaa to cnloulata an abaorbad doaa In a watar phantoa froa lonlzatlon ohan-bar Baaauranenta. Elthar tha oallbratad lonlaatlon ohambar la Inaartad Into awatar phantoa and tha doaa la oaloulatad froa lta raad-out by th* oavlty thtorj,or tha txpoaura la maaaurad In tha aaiia dlatanoa In fraa air gaoBatry and thadoaa la oaloulatad froa tha axpoaura ualng tlaaua air ratio. Tha aaoond aathodIs ralld only whan thara la no additional oontrlbutlon of aoattarad photon* froawulla or floor.

Tha output faotor* for dlffarant aat-up of Chlrana'a oobalt aaohlna* wora aaa-•urad In a watar phanto* at tha dapth of 50 an and at dlffarant S3D dlatanoaa.Tha raault* ara auBmarizad In Fig. 4. Uaing again Oauaa-Rawton's mathod for fit-ting of the ourra In Fig. 4 by aquation>

- a, - ag.axpC-aj.f ) (9)

tha paraaatara •1»«2 and k3 w#r* found to D- 1« 15 1 * 0.010, 0.283 - 0.00? and

8.165^0.626, raapaotlraly, with th* ooafflolaat of aultlpla oorralatlom T « 0.996.Tha ourra In Fig. 4 waa again noraalltad to tb* atandard oolllnator a**-up f «76.92. In tha lntarral of th* oolllaator aat-up froa -8.3 to 254 aradiana th*•aaa atandard darlatlon of tha axpariaantal r»).uaa waa laaa thaa 0.5 9. It ahouldba notad that all aaaauraaanta of do** output faotora war* oturrlad out la th*ranga froa 0.6 t* 1.6 a for aouraa to phantoa dlatanoaa. Th* diatanra of ianlaa-tloa obaabar froa ta* phantoa bottea waa at Iaa4t 39 *a aad tb* wall *r tb* floorwaa at laaat 90 oa fraa tba phantaa.

- 58 -

Fig. 4Dependence of thadoaa output ffeotoron ooU.laa.tor angleIn Chi: 60,'Co

-0.05Iradl

Comparlaon of phantoa doaa neaaureaenta with thoaa aada In free air geoaetrywith tha usa of published TAR valuea showed that for a oollinator aat-up aroundatandard value both aathoda give the aaae rarults. It waa alao observed that thadlfferanoaa between in phantom and air aeasuraaenta baoaaa aignlfieant with aoraopen oolllaator aat-up (aora than 150 arad). The ratio of F^/FQ givea tha rela-tive dependenoe of tlasue air ratio for Co aaohlnaa uaad In our exparlaanta.Multiplying thla ratio by tha aaaaured value of TAR for a atandard oolllaatoraat-up, whloh waa in exoellent agreeaent with the publiahed one, ona obtalna ab-aolute valuea of TAR in dependenoe on oolliaaior angle aat-up. Thla depandanoala givan in Fig. 5, where alao tabulated value* '2' are ahown. Tha ourve InFig. 5 waa fitted by aquationi

TAR(50) - e, - o2.exp(-o3.f ) (10)

with the ooefflolant 0,-1.017^0.0005, 02-0.1818*0.0004, 9y6.334*0.034 and withooefflelent of aultlpla oorrelatlon r-0.999. Froa Fig. 5 one oan aee that In alaaall angle oolllaator aat-n» tha aaaaured and tabulated valueo ara tha aaa«itha dlfferanoo oan ba obaarved only 1B a broad baaa. It la dlffloult to deoidewhether thaaa dlffaranoaa ara oauaad by tha oolllaator ayaten or by photon alba-do oontrlbntloB frea an oppoalta wall ar a floor.

Oapaaaaaoa of 9UL on aoll

TAR

•an

tor angle In Ohirana wuCoahlnaa. Olrolaa ara data ta-ken froa (2), surra - exparl-aental data

- 59 -

VI. General formula for absorbed do** oaloulatlon

Th* exposure rat* Z oan be oaloulated a* any time t2 with the use of tb« pro-

posed nodal, for any point on oentral ray and for an arbitrary ohosen flald sis*

PS prorldad that tha exposure yield Vj haa oeen datarmlnad at tha tire t., under

reference oondltloss. Although In general the referenoa oondltlona may be oho-

aan arbitrarily, it Is reooamended to u»e the same MI in thla paper, l.a. SSD

equal to 1 m, oollimator set-up to 76.92 •red, whloh ia equal to tha aet-up of

73 • 100,100 mm at SSD-800 mm. In this oaaa tha derived aquations and ooeffl-

oients oan b* usad without any restriction*

Tha exposure rat* for any ehoaan aouroa-polnt of measurement dlstanoe from

tha Interval between 0.6 to 1.8 m and PS belonging to any oolllnator set-up froaj

the Interval -8.3 to 254 nradlana oan be expressed by tha equations

f-Yj.exp [-In 2.<t2-t1)/T1/2] . PS.PQ (11)

and th* dose rata at tha sama point at the dapth of 50 mm la watar phantom oml-

oulated from in air neasuramants Is equal tot

D"Vj.exp £-ln2.(t2-t1)/T1y2j .rg.Pc.TAR(50).K (12)

where T1/2 is half life of Co , v^ exposure yield measured at time t1 for re-

ferenoe , conditions, Pg is defined by eq. (7), K oonverslon faotor froa exposure

to absorbed dose, Pc by eq. (8) and TAB(50) by eq. (10).

The dose rate oan be oaloulated alao from in phantom measurement if the dos*

yield VQ has been determined under standard oonditions, I.e. at the depth 50 ma,

source-surfaoe of phantom dlstanoe 0.95 m, standard oolllmator aet-up f -76.92

mrad. The dos* rat* oan be oaloulated at any tint* t2 for any field »1E* PS and

SSD froa th* equationi

D V M-v*t I 1wi9 t + * W n "1 -m m f1"4^_,"»Ti»03CP j — ln^ . , To— *1 'I *• 1 /oA •'n»*Q \*j)W V , » « I * / m. V D

PD being defined by eq. (9).

Both equation* oan help to oaloulate the absorbed dos* in th* oentral ray at

different Irradiation oonditlon*. In order to determine the absolute value of th*

dos* rat* in any point, not only In the referano* point, on the oentral ray, th*

modal proposed by Van d* Q*ljn'-" oan be used after estimation of th* free para-

meters from experimentally established dose distributions.

The equations describing the dependenoe of the exposure or dose outputs on

irradiation conditions and presented here were derived froa th* experimental da-

ta obtained froa th* two oobalt maohines In the Radiotherapy Department in Ostra-

va on several oooaslons. Later the suggested model was verified by measurements

performed at other oobalt maohlnea of the same type mainly in Paskov and Choan-

tov radiotherapy oentros. Then some of th* oonolusions derived froa th* former

approaoh were oheoked at other radiotherapy o*ntr*s.

All results have been orltloally analysed froa the point of possible souroes

of errors and systeaatlo and random as wall as total unoertalntles have been

established, using a a*thod pabllshad reoentlj/*'. It oan be oonoluded that th*

total uno*rtalnty at th* oonfid*no* level of 92* la equal to Uj2-±1.5% fov trans-

fer of tha *xposure yield from th* r*f*renee point to any squar* field at any

SSD and for any reotaagular field it la equal t* U92-±1.71» iisid* th* interval

of SSD from 0.6 to 1.8 a and with a oolllaator s*«-op froa -6.3 to 254 mradlans.

Th* total uncertainty of DQ3-i2* waa found for th* des* rat* transfar based oa

- 60 -

In air measurements. The uncertainty oonneoted with the doa« rat* transfer fromatandard conditions to any Irradiation oondltiona based on In phantom measure-ma&ta waa found to ba UQ 2»^1,&%. The total uncertainty Including the unoertalntyof doa* and axpoaura yield deterolnatlos in the referrenoe point waa found tobe battar than - 5% at tha oonfldanoa lerel of 92%, whioh la undar tba requiredTalua for ollnioal doslmetry.

Th« propoaad motel ia simple and lta uaa lmproraa tha quality assurance Inradiotherapy. Due to tha small number of paramatara tha ealoulatione oan be easi-ly performed by a oouputer or by hand oaloulatora.

Trom tha point of riew of thla aodel a following reoommendatlon may be glrento those who are facing tha taak to gather nacaaaary dosiaetrlo data for n*wor repaired Chlrana'a oobalt aaohlnea. After oheoking teohnloal atata of thaunit at laaat 7 but preferably 13 •aaauraaanta of azpoaura or doaa outpute ahonldba perforated under different Irradiation oondltione. Thla auat ba followed bya praoiae determination of expoeure or doaa yields undar atandard oondltiona.Then all maaauremwita and proparly evaluated output ralnea are azpaetad t.. fallwithin ii»75C or -1.8* laterral arrouad their theoretioal predloto (glTen tMTig. 3 and 4) with a probability of 92*. If It ia true, tha fonwr aquation*may be aooepted and uaad to doae oaloulatlona la tha allowed interral of SSDaand field alaea.

L^teraturf

f\J Cllnloal Doalaetry of Photon and Kleotron Therapeutic Beeaa with Energiesbetween iOkeV-50 lleV. Xktual.klln.onkol. 9, 1-59, 1984.

/2/ Br.J.Radlol., Suppl. lo 11, 1972, ad. by M.Cohen, D.B.A. Jones and D.Greeaa.

/3/ J.Van da Oaijn, B.l.rraaaa. Mad.Phys.JLl, 784-793, 1984-/4/ J.Horotnf, Z.Korari &«.atandardlaaoa 5, 237-245, 1980.

H TBLETHEmFY

I.Seymozyk, J.Leeiak, B.Polok, B.Polak,Institute of Oncology, Craoow, Poland

H n t of all I hare to eay that, the subjaat ot my preaentatlon will ba most-ly lnforontory, rather than a r«s«aroh report, As Mat of the phyelolsta wortiatla onoologloal hospital* w* *n larolvsd simultaneously la sarsral fields, roufta-ly those, whloh are tha subject of tha following four seotlonai treatment plan-ning, olinloal doalmatry, quality aaeuranee, and vadlatlon proteotion. So wa ararather oonoamad In praotioal solutions.

In tha first part of this oommunleatlon Z would Ilka to present our standarddoslmetry prooedures, as performed on routine lerel, and In the aeooad part owraew approach in evaluation of biological doaaa, which is rather beyond tha rou-tine task.

Our equipment faollltlee for external beam doslmetry arei- tha automate* water-phantom Measuring system for beam data aoqulsltloa.

- 61 -

- dedicated minicomputer "Informatek" for individualized treatment planning.

The phantom measurement device is a home-made system (9), (fig. 1,2) working

in CAMAC mode, driving an ionization chamber In a water tank along a programm-

able meander-shape track. The length of the stepa in two perpendicular directions,

Pig. 1

Water phantom in

measuring position

number of these steps and the dose

value to be reached on the monito-

ring chamber are the present values.

Integrated ourrent, as recorded by

the two Ionez dosimeters, are pun-

ched on paper tape. This system is

under further development.

The dedicated minicomputer "In-

fo rmatek" is a French Treatment

Planning System. Its hardware con-

figuration is shown in fig. 3. It

has been extended by a paper tape

(and card) reader, to get the link

with the measuring system.

The dedicated minicomputer is

equipped with the software system

"Inforad" ?rhich consists of several

valuable programs. Unfortunately the

beam generating program is not acou-

rate enough for reproducing beams

from our accelerators (Siemens 18

UeV betatron and Heptun 10F linear

accelerator). The system does not

include either the summation prooe-

dure for radiation fields from dif-

ferent sources. It beoame necessary

to develop a multitask program ca-

pable to handle dose data in arran-

gements, that are used in our hospl-

- 62 -

•anuiu*

Tig. 3Hardware configuration of extended"Informatek" IPS

tal, likot mixed beams,Irregular fields, spe-cially formed oearns, mo-ving strips. Differentalgorithms have been ap-plied to the particularradiation qualities andgeometries, mostly basedon published data. The •beam generation programfor 6SCo radiation uti-lises Benassis (3) for-mula for central axisdepth dose values andprofile functions foroff-axis points (1,11).High energy photon andneutron beams are gene-rated by table look-upand interpolation of sto-red data for a number of

fields at selected depths. Calculations for irregularly Bhaped °Co and Heptun10P fields are performed applying Thomas formula (13, 12). Dose distribution Ineltotron beams Is based en measured soan data transferred to the oomputer viaa punohed tape reader* A prooedure la included to allow for the shape of bodycontour along the beam width (fig. 4). This provisional method is to be replaoedin the near future.

An auxiliary comprehensive program has been de-veloped for digitising iso-llne maps and transfor-ming them into a matrix form. In this presenta-tion, the same processing like in oase of eleotronbeam, (oontour oorreotlon, summation) is possible.

Several examples of treatment plans produoedby this programs are shown in fig. 5-10.

The individualised treatment planning at ourhospital is based on physloal doses. However theproblem of biologloal effectiveness of fractiona-ted radiotherapy got our attention, as beoause ofradiotherapy machine economy not always all the

P^ 4 fields are irradiated at eaoh therapy session.Correction prooedure for Following the suggestions of radiotherapists, webody contour for bean data taT# « * t t « • program evaluating a fractionatedpresented in matrix form radiotherapy oourse In terms of TD» faotors (10,

8) . The TOT formalism extended by Qolteln (6) hasbeen adopted. Thla flexible system has been developed for treating Irregular ra-diotherapy aohedules. Our program for evaluating lso-XDV distribution* has beenvorked out in two versions. Both are allowing for any time distribution of theindividual freotlonal doses. In the earlier version (for Co beams) seme limi-ting assumptions ware done concerning the number of oomponent single sessionbeam configurations (10). In the recent one, including leptmn 10? irradiation,any oomponent beam configurations are taken Into account, though more preoaloala-ted Input data are needed*

In ollnloal praotloe two component (alternate) sohedules with increased weights

» ELEKTRONT: E = 15 flEV i + i GAI11A CO-GO ELEKTROrjT x 12 I G / 50 / 15 d£U + 1G I 16 / 80 / 1 I B !

H.g. 5 «.Doss distribution la larynx traat- Doaa distribution la ohsst wall lrradlatad••at by odxadt Co «nd •ltotroa by two alaotron baaaabaaaaar« aoatly uaad to gat tha aaaia tuaiour doaa. An aaalyela of tha laaat faTonntblatheufh raallatle altumtlon, wh«n tr«*tlaf • daaply aaatad tuaiour (bladdar) bythree flalia la praaantad. Twc baaa qualltlaa axa oonaldarad, Hx Oa radlatioa

M g , 7D M dlatrlbutlaa la brasat traatmat by two wad«ad andblookad baaaa (halfbaaaa)

It la shown, that whan traatlng not all tha flelda dally, both OTardoaage aaddaforawtlon of tha high doaa ragloa ooaura.(flg. 6)* Thaaa affaeta ara not pra>aant whan using high anasrgy photons ganara>ted by laptva 1OP saaalarator (fig. 9)*Slallax fladlaga war* rapertad by OlttanMn (5) aad Kirk (T) supporting tha re-qulraasnt for oaloulatlag blolagioal deaaa la oaaaa of uaaonvaatloaal traatasntaohadulaa at law •agaroltags aaarglaa.

Iowa4aya tha lladtatloaa af tha Kllla' fay—da «ad Ita darlratlraa ar* wall

- 64 -

Pig. 8

Coa* distribution la

bladl.er treatment by60Co beam*

right aid* - nonaallsea

pbysloal doaa distribu-

tion

left alda - normalise*

biologloal-lB©-TD? dl-

alrlbutloa for altaraa-

U (1/243) fraotioaatloa

schedule, baas weight•

60 07 (24 fr.) 32 daya

Dose distribution la

bladder treatwjeat by

"Raptun 10P" betas

right aide - normalized

phyaloal doaaa

left aida - normalized

biologioal-ieo-TDP distri-

bution for alternate (1/

2-t-3) fraotionatloa soha-

dula, baaai walghta 1t2«3-

1t1.2t1.2, 60 Gy(24 fr.)

32 days

raoognliad (2). HowaTer, tha publlahad reo«ntly by Cohan (4) Bllla-llke foraulaa,

approiinating lao-affaot tablaa for aararal normal yulnarabla tlasuaa, offarad

tha possibility of extending tha application rauga of blologioal dosa oaloula-

tlona, whila ratainlng the faalliax TDP fora*liaa.

Ths ganaral expression for tha axtandad TDP and TDPtol faetwra la tama of

th* paraMtazv of tha Bills-typa formal* /Dtol-HSB.T*3V, as darlrad straight

fro* tha dtfinition of TDt faotor aad partial tolsranet, arat

tol "wherej

10"3

A—1/U+b-i)1- a/(a+b-1)

Humerioal raluea of tha two sets of blologloal response paraaetera, for sa-leoted nonal tissues, axa giran In table 1. Tha worked out oonputer prograai •an-tioned bafora makes allowanoe for tha speelfie exponenta A aad B la IDT equation,for tha tissues of inhereat, to ba (ITSB aa Input data. An exaaple of oaloulatadTDP oharaoteriatio for oonnaotlTe aad gut tiesue, la abown la fig. 10 la treatingtha abdOBea by aoTlag atrip taoholqua. The nhyal»al loa* has *»m o*tlal*a4 by

Tabla IBleloglaal tlaaua tolaranea paraaatara

tlaaaa

oonnaotlra

gutkidnay

IflD

1780

1580

465

a

0.11

o.oe0,19

b

0.240.290.25

ro»tol100

11958

A

1.5381.5871.786

B

-0.160

-0.127-0.339

M g . 10Two auparlapoaad oonaallsad lao-TDP dlatrlbutlona In BOTlng atriptaohnlqua_____^______ oonnaotlra tlaaua— — — gut tlaaua (••• taxt)

auooaaalra adjuating of arary naxt atrip wtlght (22.5 0? In 10 daya-prlaary doaa).Tha two auparinpoaad lao-TDf dlatrlbutlona for tha two normal tlaauac oonaldaradart norrnallaad to 100* at tha targat raglon. Tha oorraapondlng TSV and ?D'toi

T*~luta, Inoluding kldnay tiaaua, ara glraa in tabla II. Tha high TPf raluaa for kid-nay impliaa that looal ahlaldlng ia naadad with at laaat two "*ialf Talua lay era"blooka.

Thia aampla of oaloulatlona eoabinlng Ooitain'a fornallaa and Cohan "a paraaja-tara llluatrataa a naw approaoh In quantltising radiation tolaranoa in aalaotadnormal tlasuaa, whan irradiatad In an untyploal way.

It ahould ba addad howarar, that apart from tha fundaaantal dlffloulty aaaoola-tad with applying a alapla powar law funoticn In daaerlbing a ooaplaz oall kina-tlo naahanlaa, aoaa aablgulty la lnharant whan lndlTlduallsing tha auooaaalva frao-tlonal docaa. Tha waak point la tha tiaa intarral, daflnad aa ralatad to tha laatday of Irradiation, but oould aqually wall ba ralatad to tha naxt ona, aa atraaaa«by Seitain (6). Thia aabiguity baoaaaa aapaolally anhanoad in altamata fraotle-nation raglmaa, whan aaall and big doeaa ara dalirarad auooaaalraly at unaqual ti-aa intarrala. Moraorar, if tha aaall doaa la rtxj lew (froa aeattarad radiation),a problaa ariaaa If not to naglaat It aad axtand tha tlaa intarral baok to thalaat big doaa, blggar, than an aaauaa* thraahol* valua (now bigT). A aafa praa-tioa ia to kaap tha hlghar Taluaa ana ohaok tha oaloulationa for taa "rararaaa"tiaa intarrala.

Kararthalaaa, tha alapllalt? of tha TD? ay ataa la attraotlra and anoouragiag

Tabla II

TD7 raluea in aorlng atrip taohnlqua

tisaua

oonneotlva

gutkidney

34.6

45.0

1(0.0

100 TDP/TD»tol

/*/

34.6

37.2

240.0 1/

1/ if unehlalded

to uaa with lnprorad paraaetera, untill aore elaborata syataoa baoaae routinelyarallabla.

Ending X would Ilka to a*y, that wa ara fully oonaoioua of aararal waaknaaaaa

la onr doaiaatry u l I u oonTlnoad that thla atetlng, whloh la as axoallaat oppor-

tunity to axohanga expertenoaa, will ba affioiaut In aooelerating loproreaenta.

Literature

1. Allewaert,J.A.j Coaputstlon of two-dlnanalonal doaa dlatrlbutlona 1" Co60-

t«l«tharapy with ooplaaar t>*»m», Fhjra.Mad.Blol. 1972, 17, 613.

2. Barendsen, G.V.> Dona frmotionatlon, doaa rata and laoaffaet ralatlonahlpa

for normal tlaaua raaponaaa, Radloblologloal Znatltuta THO, Rljawljk, Tha Hathar-

landa, 1982.

3. Banaaal U., Poulxl, R.: An •mpirioal foniula, oontlnuoua In flald paraaa-

tare and dapth, for tha axial doea for Co 6 0 ganma radiation. Brlt.J.Radiol. 1972,

45, 475.

4. Cohen, L., Cradlttr, H.i Isoaffaot tablaa for tolaranoa of irradiftt^d nor-

aal human tleauaa. Int. J. Radiation Onoologj Blol. Phya. 1983, 9, 233.

5. Oitternan, H., Littaan, P., Doppko, C , Wang, C.C.i Rethinking tha naeaaal-

ty of tresting all flelda at eaoh radiotherapy aaaaiou. RadioZosy, 1975, 117, 419.

6. Solteln.K.t Tha ooaputatlon of tlaa-doaa and fraotlonatlon faotora for irra-

gular treatment regiaea. Brit. J.Radlol., 1974, 47, 665.

7. Kirk, J., Owen, W.H., Wlngata and Wataon, E.R.i Hlgh-doaa affaota in tha

traatment of oarolnoaa of bladder under air and hyperbarlo oxygen oondltlona,

Clln.Radiol. 1976, 27, 137.

8. Orton, C.G., Ellis, F.i A aleplifloation In the uaa of tha ISD oonoapt in

praotloal radiotherapy. Brit., J. of Radiol., 1973, 46, 529.

9. Polok, B., Ssyacsyk, W., Opallnakl, R.i Autoatotyomy seataw do poalara •ar-

toaol dawak terapentyo«ayoh w iysteale CAMAC. Probl.Teohn.Hed, 1986, XVII, 1, 35.

10. Szynozyk, t., Kowalocyk, H., Laaiak, J., Koraanlowaki, S.i Syataa TDF w ta-

laradlotarapll kobaltowaj. lowotwory, 1986, XXXVI, 4.

11. Siyaoryk, W., Folak, B., Byrakl, X., Staroatka, H., Jalanak, B.» Charakta-

ryatyka prograsm obllo««n w taleterapil Co60, Bowotwory, 1978, XXTIII, 4.

12. Siyaosyk, W., Leaiak, J., Jelonek, B.i Charaktaryatyka prograau O B U C M -

nla dawak w obaiaraa nlaragularayeh pol wlotovyah vlaaki kobaltowaj. Vowotvory

1980, XXX, 4.

13. Thoaaa, R.I>. t A ganaral azpraaalon for •aga-roltaga oantral axla doaaa.

Brit. J. B*4iol. 1970, 43, 554.

- 67 -

Q0WTARI80B OT THEORETICAL

AJD EKPKRIMEHTAI, DOSE DISTRIBUTION

QEKgRATED BY THERAPEUTIO ELECTBOB BBAJB

I. HlarASo-nf, X. Tobola, D.

Radiotherapy Department of Regional Hospital,

Ostrara

Abstract

Speoe distributions of abaorbed doea generated by alaotron Therapeutioal beams

from 31amana 500A betatron wara maaaurad In tha aalf mada automatio water phantom

oontrollad by tha EMO 666 oaleulator. Tha read-cuta of two ohemnel lontometrio aya-

teas wera evaluated and transferred to floppy. Thaae ezparlmantal data were ooapev-

rad with Hogstrom's and Kawaohi's mod«la. While our attemp to adapt Kawachl'a frea

parameter* to tha experimental distributions failed, a quite good agreement was

aohleyed when comparing experimental profile* and thoae oaloulated by penoll beam

model of Hogetrom. Without any experimental weighting faotor the agreement la olo-

eely related to the degree of homogeneity of the beam. Influenoa, fit homogenising

aoattering foils on the initial aoattaring angle la disouased in the paper, aa

well aa the possibility of the oentrsl beam depth doae ealoulatioi.

I. Introduction

To ensure effeotlre electron therapy planning, detailed information on dose

distributions in tissue equlralent madia for different types of irradiation Is

required. Although the amount of necessary measurement* may be redueed by using

mathematical models or algorithms, neoesslty still demands to hare a relatively

large set of experimental data, at least to be sure that the use of the speclflo

model or algorithm is well-founded.

Therapy planning In our department la performed on the therapy planning oon-

sole EVAD03 with software equipment SIDOS. There la no mathematical modal for

oaloulatlon of alaotron dose distrlbutiona in this system, laodoses are oaloula-

ted on tha bade of a dose diatributlon matrix, which must be Introduced Into tha

memory of the computer by the user. As we do not dispose of a sufficiently fast

and mobile oomerolal mapping system, we hare to paaa a rather complicated w«y

consisting of following main tasksi

1) collection of representative data set,

2) generalisation of this set by a pnysioaj.lv well-founded model,

3) transfer of the data set into the memory of the EVADOS.

Up to now, we hare, to a oertaln extant, fulfilled the flrat two taska, whloh we

ahould demonstrate in this paper.

H . Experiment

1. Realisation of the experiment

Eleotron or photon beam from Siemens 500A betatron waa passed through a plexl

window 16x16 oaT (thlokneea of the window wae 3 mm) Into a oube 30x30x30 oa3 ma-

de of 1 om thick plexl and filled with watar. Tha epaoe diearlbutlon of tha ralar-

tlre lonliatloa currant waa meaeured waixif the aalf mad a Measuring ayetem flrat

desoribed in Marlanake Umni In 1983 (aea /I / ) . We ahould briefly auaaMO-lae lta

main features nowt

- 68 -

Pig. 1

A dosemeter Viotoreen Radacon II with a measuring ionis&tion chamber IC-100with cavity diameter 3.6 mm, moveable in two directions (in the acceleration pla-ne in our case) was connected through a data acquisition system METRA and throughan interface with the input-output bus of the desk computer EBG 666. Instead ofa reference chamber one of the two channels of the betatron monitor system wasused being connected to the METBA system through an adapting RC element. Conti-nuous movement of the measuring chamber in the water phantom was enabled by usinganalogue control of balancing servosyatem. A double channel digital-analogue con-vertor connected the input-output bus of the calculator with the control unit ofthe water phantom. Back information on chamber position in the water was conduc-ted back to the computer through the METRA system.

2. Data processing

The measured data (voltages at the resistor paths, ratemeter response, refe-rence current) passed through the METRA system into the calculator to be proces-sed there. The correction of the efficiency of charge collection was made for themeasuring chamber and finally the ratio of the measuring and the reference cur-rents, was made and stored in the external memory together with the chamber posi-tion coordinate*.

The stored data were converted into the dose distribution pattern by includingthe influence of stopping power change with increasing depth and the perturbationfactor of the chamber, both being performed according to (2).

Geometry and voltage of the reference chamber (electron beam transmissionchamber, separation of electrodes - 1.5 mm, voltage 1000 V) guaranteed the re-oonbination being sufficiently small (less than 1%) to be neglected.

Having thus got a point dose distribution we found out, that it should be use-ful to smooth the curves, as in many cases they were distorted by small fluctu-ation of several percent. Therefore oonvulatlon smoothing was performed, i.e.smoothed value* of point dose were evaluated according to the following prescrip-tion

1/2 ,DC*0) - d ® * -_i/2 dixo-x >.f(x ) dx

- 69 -

d ... measured dose distribution

t ... auxiliary function defining the way, in whioh the values in the next points

are taken into aooount

1 ... width of the convolution integral

Triangular, reotangulex or Gaussian function was used In the place of auxilia-ry funotion f (aee Fig. 2).

23v_-: ; , ,

triangular: »

i

*

t

/

—* *

——1

•

*

7'

-ii

•

•rectangular:

f(t)=J-

*

V. gaussian 3

•

• \

*

Fig. 2

Central axis depth doae curvea gained by this way served as the groundwork for

the mathematical dose profile calculation (see section III).

3. Experimental results

Central axis depth dose curves (curves of relative ionization) were measured

for all therapeutlcally used field alces,i.e.fields in cn2:4x4, 6x4, 8x6, 10x8,

12x8, 14x10, 15x4, 16x12, 18x6 for SSD 100 cm, 20x14, 20x20 for SSD 120 c« and 8x6,

10x8 for SSD 140 ooi Field sizes beam profiles in depths approximately 1 cm, ma-

ximum dose, therapeutical range (85%) and 50% of maximum were measured for chosen

energies.

Nominal energies of electrons were 7, 9, 12, 16, 20, 25, 30 and 40 MeV. Para-

meters of the used scattering foils are summarized In the following table:

numberof

f o i l12345

material

NlPbPbPbPb

thickness

0.25 mm0.10 mm0.35 mm0.80 mm1.40 mm Tab. 1

The error analysis led to th» conclusion, that the real values of the relative

dose should occur with probability 0.92 within a "rectangular tube" (4.8 mm) 2 x

- 70 -

3.2%. The procedure of the error analyala oan be followed beat la tha Tab. 2.

poaitioa ayatematlo uncertainty

chamber dimeneiona a-,

uncertainty of poaltion

random uncertainty ft

total uncertainty of poaitioa Ug2 • "\

relatlradoae

•ystematio uncertainty

responae stability

raaponaa nonllnearlty •*

energy dependence J

souroe fluetuatlona

random uncertainty

total uncertainty of relatlre doaa

Tab. 2

•2<

1(2 €

<

<

<

0,

0.

0.

0.

3.

U 0

2 an

1 aa5 mm

2+ 3 < 5 ^ .2.4-1

5*

5*3*

25*2*

III. Mathematical modal

Abore la described, how wa got experimental data from our aooelerator. It waan't

emphasized, however, that our peaeuramenta wara rather tlme-oonaumlng (mapping *

field of else 10x8 om2 for 30 MaV takaa about 30 minutea of meaauramant). lUrther-

•ore, aa it waa mentioned already, there waa no poasiblllty of meaeurlng profilaa

in tha plane perpendloular to tha aooelaration one. Therefore It appeared neoeaaa-

ry to find out tha way, bow to generate a complete aat of doaa data out of a rather

•mall amount ot experimental data. Wa aearohed for a mathem*tloal modal, whloh would

enable ua to fulfil this taak.

Tha flret modal triad waa Kawaohl'a age diffusion modal aztemdad by MmAla (aee/

4/,/5/), whloh deaoribea doaa dlatrlbntloa by tha formula

a +x a -x b +y b -y

3SD+I

at-a/A, bB-b/A ... field alsa la depth •

D%(t, K T ) repraaaatiag tha oentral azla depth doaa curre

la girnn by tha relation

whera tha only free parameter la g2 (other gA ara partly ooaetanta and partly de-

pend oa g 2 ) . The remaining two paramatara of tha modal - o and r - appear la tha

formulae for X T and H (for detailed Information aee /5/).

i Wa left tha modal after * abort time for aeyeral reaaonai

1. failure In flttlag tha parametara for daptb doaa dlatrlbutlon,

2. no obTloua depeadaaaa batwaea phyalaal paramatera of the beam (eleetroa aaergy,

aeatterlng fella •««.) ant the aga flffualoa paraMtar,

3. avldamt <laagreamaa1 la aaaa tt unaytMtrla aoaa dlatrlbutlam,

4. aeoeeally of meaaurlag aaam profile fr aaah kaaa to fit all tha panuaatera af

tha modal.

Another wall knowm aatkMMitloal model la baaed oa tha paaoll kaaa appraaah. 9a-

talled darlTatlea of ita formulaa aboule be uaalaaa u • loat of authors bara mX-

- 71 -

raady mad* 1* la»m /(,/, /?/, /B/)t parhapt only tha M i a prasuaptlona atandlag latha baaaa of tha thaory ahould ba ranlndad.

Lat ua auppoaa that ralatlTlatlo alaotrosa paaalng through tha aattar loaa thalranargy aolaly by laslaatlo oolllaiona (by small aaounta) and alaultanaoualy ohan-ga tbalr dlraotlon by aultipla aoattarlngi l.a. by aaall anglaa. Thaaa twc pra-auaptlona ara fully juatlfiad whan tha dapth a la anall In comparison witi thapraotloal ranga of alaotrona R but fall naar tha and of alaetron panatratloa.

*ha dlatrlbutlon function ?(z,0| a) In oaaa of alaotron panoll baaai (a twodlaanalonal problaa la oonaldarad firat) aatlaflaa tha Farml'a dlffualon aquation

(* and x rapraaant angular daflaotlon and lataral displacement of alaotrona). Iftha raal baas la oonaldarad aa a oollaotion of panoll baaaa paaalng through thadlatant baaa of tha tubtta, tha doaa In aaoh point* oan ba oaloulatud Ilka • aupar-poaitlon of dosaa fro* lndlYldual panoll baaaa, l.a. Ilka an Intagral of tha pan-oil baaa doaa funotlon ovar tha oroaa uaotion of tha raal baaa. Ualag tha Sygaa'asolution of tha Parai'e aquation tha following foraula la galnad for tha dlatrl-butlor. funotlon P(z, y, a) in oaaa of a hoaoganaoua raotangular baaa (tha aola-tion waa axtandad to thraa diaanalona, tha angular dapandaaoa waa axeludad)t

'initial •" oonat*Bt oharaotarlalng tha dlatrlbutlon lsoidant on tha aurfaea oftha aattar

A 2 ..........squara of tha apaolal dlrarganea of tha baaa in dapth a

wtaar* •&(%') aaana tha aaaa angular aoattarlng powar.If tha oantral axla dapth doaa distribution la known and it la juatiflad to

auppoaa that tha aaan anargy (and tharafora tha •topping powar) la oonatant throughtha dapth laral a, tha unknown ^initial oan ** •xolud*d •ad *"• dapth doaa oaa baoaloulatad uaing tha formula

Dn(z) a +x a -x b +y ' b -yD(x,y..) § p ( a r f ^ •erf-^O (erfr^r ••rfjAr)

whara D Q ( B ) danotaa tha oantral axla dapth dosa dlatributloa.And now a faw worda about tha applloatlon of tha aodal. Wa daralopad a prograa

In BASIC callad "alaotrona"^ whloh parforaa all tha oparationa aantlonad In thispapar. A part of this prograa oallad "profllaa" oaa oaloulata baaa proflla la ar-bitrary dapth s supposing tho oantral axla dapth doaa eurra .la known.

Tha agraaaant algnlfloantly laprorad whan a quantity oallad "Initial soattsrlagangla* waa lntroduoad ao that

This quantity rarlad froa 0 to 0.3 rad dapandlag on tha noalnal anargy of alaotronaaad tha width of tha aoattarlng foil. Tha higbar tha ansrgy, tha saallar was 6jLitba highar tha auaaar of soattsrlag foil, the hlghar was •1. It wasn't posslbla,hawarar, to salsulatt tha Initial aaattarlag aagla fro* tha kaawa paraaatara aftha aaattarlsg foils, baeaaaa tha angular distrlbutlaa af alaatroaa Is abora allfaraai by tha twWsas and »• Its dapaadaaaa aa tha falls aaaaot ba axpraaaad ay

- 72 -

simple mathematloal formulas.la far as the central axis la oonoerned, oontlnuous slowlng-down approximation

doaau't yield results, whloh should agree veil with the measured currea. Thereforewe stayed oontent up to now with the eaplrloal algorithm we presented In 1984

Do(.) - [co.(-§- + a) b + o] .

Certain dependences of parameters a, b, O on physloal parameters of the cleo-tron beaa wer« found out for broad beaas. How we are going to determine more ezaetformulas for these parameters and to oxaalne the posalbllltj of using some slad-lar formula In the ease ot narrow beams. Therefore we shall present our oonolu-slons about the oentral axle depth dose problem next tlmo.

literaturei

1 1. Stankus P., Tobola K., SpaSkora' D., Flanderka J.t AutoaatiEOYany' doclmetrlo-k^ syatim pro mapoTani terapeutlokôh sracku tirfai. VI. sTmpoalum on radiationdosimetry. Uarlansk^ Usne, 28.11.-2.12.1963.

2. KUniota doslmetrle terapautlokôh fotonovôh a elektronoT/oh srascfi T obo-ru eaergli 10 keT - 50 HeV. Aktual.klln.onkol. 8, Bratlslara, deoeaber 1984.

3. BoTotn^ J., Koire-r Z.i Stanorenl nepfesnoatf prl TyhodnoooTani doalaatrlok/ohaereni, 5eskoalovenski atandartlsaoe (5) 1980, 8. 6.

4. Kawaohl K.i Caloulatlon of Electron Dose Distribution for Radiotherapy Treat-ment Planning. Pays. Med. Biol., 1975, rol.20, B . 4 , pp. 571-577.

5* Vflslln 7.i A ettaple Jtod«l for Oaloulatlng Dose Distributions In Hlgh-toer-gy Eleotron Therapy.'lai J.Bur.Radlother., 1980, S.I, n.4, pp.193-197.

6. Hogstroa K.H., Mills M.D., Alaoad P.R.i Xleetron Bean Rose Caloulatlone.X m Phys. Med. Blol., 1961, Tol. 26, n.3, pp. 445-459.

7. Koslor A.P., Shisher V.A.i Oaleulatloa of Hlgh-toergy Vleetron Dos* Distri-butions in Tissue-SqulTalent Me«â Strahlentheraple 158, 1982, n.5, pp.298-304.

8. Jette D., Pagnaaenta A., lansl L.E., Raienfeld M.i The AppUoation of Mul-tiple Soatterlng Theory to Therapeutic Kleotron Dosiaetry. Ini Med.Phya. 10 (2),1983, pp. 141-146.

9. Tobola X., EUvtfc'oTa' ZJl.t MedeloTani elcktrcnevy'ea sraakt, paper preseateiat the meeting of tae radiological physles eoaaltt»e ef the 8eelety af OBoologyJ.S.Purkyae.

VfAMD A W A l l OORREOTIOI fAOTOt

60

X, Ko'rar,

Institute of ladlatlea Doslaetry, la truklarc* 39/64,Prague 8, OseohoaloTakla

Introduotloa

The oorroetlea factor denateA i , ^ la tala papa? 1> ••«»•* ky /I/

- 73 -

" *KKool

whara

ol

(1)

(2)

(3)

Kool *• M U l l i o n karaa at a point P In air, la th« abaanoa of tha ohaabar, ^la tha absorbed doaa to air lnaMa tha air oarlty of th« lonlaatloa ohaabar, Kla tha ohaaber aeter reading (In Couloaba) whan th« ohaaber la oenterad at P antla oorreetad to atandard teaperature and preaaure and for humidity, reooabinatienand atea ourrant.

Tha oorraotlon faotor A^ oan ba oaloulatad froH

Am • ( *7a/f 'n.air • "air.m ' t4)

;wh»n tha wall and build up oap ara of tha aaaa ajatarlal a, and froa

?7 )' an'f 'oap.alr-'mr.oap (5)Am m*'1 ?7n/f)wall,«ir-8air,wall *

In oaaa tha matarlala ara dlffarant. Coaffloiant la tha ralatlra fraotlon ofionleatlon In tha oarlty dua to tlaotrona arising In tha ohamber wall.

Tha correction faotorphotona In tha ionlcatIntroduction of tha aqu&tlon

takaa Into aooount th» attanuation and aoattarlafof photona In tha ionlcation ohanber at tha tint of calibration In tha Co baaa.

"wall 1-w.t

by Hath and Sohule / 2 / t whera t(g.oa~2) la tha wall (and oap) thiokneaa and w la

a tabulated function of dlmanaiona of a ohaabar, haa anablad a oonparlaon of •••aaurad and oaloulatad raluea of *wall with thaaa giran by aq. (6).

In thia papar, build up ourraa, i.«. tha dapandanoa of tha ioniiation ourranton tha wall+ oap thloknaaa, wara naaaurad for two oyllndrloal, Baldwin Paraar2505 and VAK 252.1, lonleatlon ohaabara In dlffarant Co baama. Tha A w a l l oor-xaotion faotora hara baen oaloulatad from tha naaaurad build up ourraa and araoompared to thoaa obtained by aq. (6),

Experlaant

60,,Ueaaurananta wara parforaad on tha thorapautio Co unit "Chlaobalt" with •

diaphragm typa oalllmtor (at Inatltuta cf Cllnioal Onoology, Bratlalar*) fordlffarant fiald alsaa at SSD - 1a and on tha priaary atalon 6 0Co baaa /Inatltataof Radiation Doalaatry /IHD/, Praajua) at S5J> « 1,5a aad SSD - 4a.

Tha two oylindrloal ohaabara ara deaoribed in tabla Z. Cyllndrloal aapa afdlffarant thloknaaaaa wara aada of aoryllo.Tabla Z. Daaoription of tha ohaabara

ohaabar

Baldwinfaraar 2505

TAX 252*1

oarltydiaanalona

/oa/

r - 0,291 - 2,2

r - 0,161 - 0,5

noalnalTolua*/oV/0,6

0,05

wallaatarial

tufnol

alr-aqalT.

wallthiokaaaa/ « . * " 2 /

0,050

0,104

- 7* -

Method

Initially tha awthod of Coraaok and John* /3/ waa applied, but tha trial ta

repreaant build up ourvea In Co beana by eq.

J(t) - A.e" 1* - B.a 2 # (7)

waa not auooeaafml. Tha typloal reamlt of auoh a laaat aquarea fit la on fig. 1.

Jig. 1

Relative ionlaatlon ourrent va. wall* oap

thloknear. Plane parallel "Merkua" ohaaber,

°Ce etalon beaa at ZRO, oirolaa - 899 • 4a,

trlaaglaa - SSD . 1,5a. Tail llnee - fitted

by eq. (8), daahed line - fitted by ea. (7)

(for BSD - 1,5a only)

Zha fusatloa (7) llaa balow tha aaaaurad ourra In lta band (approxlaataly la taa

intarral (0,2, 0,5) g.oa"2) and fall a off aora (julokly In tha daaoandlng part of

tha ourra.

Substantially battar agraaaant baa baan aohlarad by tha dapandaaoa

Ht) m A.a ' - B.a r 3 (8)

Tha prooaaa of oaloulatlon of A w >2x oorraotlon faotor froa build up ourraa glran

by thla aquation and following tha aathod of Coraaok and John* /3/ baa baan daaorl-

bad alaawhara /A/. Thla aathod haa two drawbaokai 1) tha oalculatad valua of ^ ^ j j

Igaoraa tha build up raglon and tfaua la ralld for graat thlokneM of a ohaabar vwall only, 2) tha •«,. (8) rmmitita to oorraot phyaloal Interpretation.

Havarthalasa, tha eoapllanoa of aq. (8) with aeaaure* ourraa haa lad ue ta tha

following dapaadanoa of tha doaa Sa(t) In tha ohaabar wall on lta thloknaaa t (par

unit energy fluanoa)i

j .dX +

(9)

. t ) .

In thla aquation, axp(-/f4 ,(t-x)) la tha probability that a photon will paaii a

dletanoe t-x In the wall without lnteraotlon, /fj.dx la tha probability of lta in-

teraction In eleaent dx giving riaa to a Ooapton alaotron, 2 y ^

{-/* 2*x~My* * im tli# M a * * n a rS7 dapoaitad by tha alaotron in depth z par volt

abaorbar thloknaaa dlTldad by tha total alaotron energy abaorbed. Tha aaoond addaaa

repreaanta tha doaa dapoaitad thore by eleotrena lnoldont an tha ohaaber.

Tha lonisatlan ourrent J(t) la proportlanal to tha abaorbad doaa, eoeffloleata

f*\* 1*Z* M$ a a d < £ w* r* aatlaated by Oauaa-Iawton ltaratlra laaat aanarea aathad

trtm aaaauratf ourrea. ,

Tha i^n oorraatlon factor aay alternatively ba defined by

- 75 -

whara X Q o l B(0) is th* oolllaioa karaa la aatarial a of tha ohaabar wall at itsenurfaoa.

Supposing tha aolllaloa karma daoraasaa as tha absorbad dosa for sufflolaattblokaass of tha wall,

*„„! -(*) ~ A 1 • •*"*1*t (11)

than(12)

wh«ra

ft - DB(t) / Kool B(t)

is tha absorbad doaa to ooUiaion karaa ratio in tha ehaabsr wall and

(14)

lv a oorrtiOtion for attaauation sad soattaring of photona la tha ohaabar y ,thus balnc tha affaotlra ooafflolant of attaauation and aeattarlng of photona latha obanbar wall. Tha ratio /3 ia oaloulatad froa aq. (13), (11), aad (9).

Danotlng /3,-liBb^ ana thanks to tha faot that /^.t « 1 for tba wall thiok-nass uead, wa obt

for suffloiantljr thick walls. This la our analogy of Bath and Sohuls'a aq.(6).

Results

Tba dapandanoa of ralatlTa lonltatlon ourraat oa wall^oap thioknasa for thatwo ohambsrs la on fig. 2. Tha auras of tha two ehaaaara wara not distinguiahaHain tha Halts of aaasuraaiaiit arrora. Tlguraa glra tha aqnara fiald aiss at 3SD •1M and Chlaabalt ualt. Higher surfacs dosa and slawar daoraasa with inoraaalagfiald aisa oolnolda with rasults of othor papara /5-10/.

M g . 2Ralativa ionlsatlonourrant rs.wall-foapthloknass. Baldwin Far-Bar 2505 and YAK 252.1.Chlsobalt, dlffsraatfiald alsas at SSD . 1a

Pig. 3 shows tha maasurad and oaloulatad dapandanoa of A w m l l oorraotlon factoron tha wall+oap thloknass. Straight linae (TAK, BY) raprasantlng lath aad Sohuls'saq. (6), i and g wara aaasurad on tha atalon baaa at IRS, for Jj tha souroa to ohaa>-b«r dlstaaoa 4a, j| ...1,5a, othar ourros wara aaasurad oa Ohiaobalt (SSD • 1a),with fiald slst 31*25 and 25oa (£), 18,75, 12,5 aad 10 oa (a.), { t i n axtrapola-tlon to saro fiald olsa. Satisfying is tha aquality of lath ana Sohuls valuss withtha aaasurad baaa i. Thia baaa aaong tha aaaaur«a onas aost approaahas tha ooaal-tloas apJUiad ta Mont a Oarla oaloulatloas i It is a broad koaa with tha laast fluaa-aa of photons aoattaraa otharwiaa than la tha air. Tha aaasurad daoraasa of

- 76 -

Pig. 3Awall VB* w a l l + C B LP thickness. VAK, BI" - eq.(6)

b, c - °Co beam at IRD, b - SSD-4m, o - SSD=1,5md, e, f - Chisobalt, SSD=1md - field size 31,25 and 25ome - field size 18,75, 12,5 and 10oaf - extrapolation to zero field size

with t Is higher than predicted by Hath and Schulz.For a given beam, the A,^^ correction factor Increases with increasing field

size (fig.4, olrolee denote the etalon beam).

0.995

0.990

0,985

- (1=0.5 9/cm2)

: J-

, i

C[e»]

i i

1 1 1)-

, l i

£i«. 4Awail VB* ^ e ^ size.Circles - IRCSquares - Chisobalt

10 20 30

0.03

0 02 -

• \H

Cfcm]_i

Wg. 5Jl^ re. field size.Circle* - IRDSquares - Chisobalt

0 10 20 30

The effdotire coefficient of attenuation and scattering of photons decreaseswith increasing field size (fig. 5) as well as the dose to collision kerroa ratio/3 t (fig. 6).

References

1. International Comaission on Radiation Units and Measurements, ICRU Report 35.ICRU, Bethesda, Maryland 1964.

2. R.Kath and R.J.Sohulz, Med.Phys. 8, 1981, 85.3. D.V.Cormaok end R.E.Johns, Radiat.Rea.1, 1954, 133.4. J.Novotny, E.HniJcova, L.Hobzov^, M.Jaohimova, I.KoTar, Z.Kovar, J.UliSny

a R.Wagner, Vy~zkumna zprira Hvz SsAV 173/85, Praha 1985 (in Czech).5. S.G.P.Cecatti, P.P.Pereira, M.P.Silva, J.P.Conoalvo, E.R.Cecatti and P.N.Pe-

- 77 -

1.004

1,303 -

Fig. €ft ., T S . flald slaa.

Cirslaa - IRDSaaaraa -

10 20 30

ralra, Radiol.Braa.16, 1983, 301.6. ?.HsAttix, r.Lopos, S.Owolfcti and B.ft.Fallwall, Mad.Phya.10, 1963, 301.

7. B.Illason and A.Brahae, nva.Va4.Blal.24, 1979, 901.tt K.OnulkrlahnaBp ati<ehloathara»la 1J«, 1W0, 9<t.ft. F.C.H4«tiii»«, Q.M.Rlkata, F.ft.AttU M i I.R,*alliMU, 8IH.nyt.10, 1NJ, C M .

10. J.TWI da Oaljn and B.A.Vraaaa, Ha4.Tkya.11, 1 W 4 , 7t4.

PITTALU5 15 DOSJOUTHlWITH TnBRMOLUMISESCKNCB D03BMETBRS

M. Oantohaw,

lBitituk» of Onoolagy M tht Madloal Ao*d«ty, Sofia, Bulgaria

Raferrad to Horl&c and Comptoa in ICRU-r«part 24 /2/ It la atatad that in ra-dio tharapy tha lntaudad daaa haa to b« glTan with unoartalaty laaa than 5%, aato aroid uaazpootcd tiaaua affaota dua to althar OYOX» or undardosing. Conalda-ring that tha total unoartalnty in radiotharapy ia pilad up froa tha *rrort intha dosimttrloal oallbvatlon of tho troataant aaohlna, in tha alngla baaa doaadistribution data (aatrleoa or laodoao oharta), in tha doaa planning proooduraappliad, in tha aoquiaitlon of tha anatoaio-topographioal input data, and andingby tha arrora in tha aat-up of tha patlanta body and tho irradiation data at thaaxaoutlon of tha traataant plan, tba aohlavaaant of a 5% aoouraey baooava quitaproblaaatlo oxan in tha oaaa of irradiation of a stiff anthrpoaorphioal pha&toa.To all thaaa souroaa of arrora in olinioal praotloo ona has to add tha tmoontrol -labla aoraaanta of tha patlanta body, and aainly of taa anatoaloal atruoturca lait. Xt thaaa alrouastaaaaa IB-TITO doalaatry ohaokiag baooaaa -nrj iaportant fortha quality aasuranoa of routlna radlothorapy and haa to ba appllsd always «haa-arar taa inaartlon of dosoaatars In tha lrradlataa part of tho baa> la taohnlaallypoaalbla.

On tha purposa of ia-vlTo doalaatry tha tharaalualaasaaaoa {th) dasaaatara ara•oat popular baoaaaa thay ara saall la alta, dataohad fraa taa raad-aut dvrlaa,and hanoa amabla tha aaaauroaant of tha afeaorta* dasa la savaral palata slaalta-naously.

- 7B -

The TL-doalaatry aqulpmant oonaldarad la this ocoanmloatlon oonalata of Har-show'a Tharmoluminasoano* Dataotor 2000 A with th« Autoaatio Zntagratlng Piooaa-paraatar 2000 B and tha X-Y plotter "Sarvigor 733"* Tha TL-wttartal ia Haxahow'aTIiD-100 in powdar font and roda 0 1 wa x 6 aa. Whan powdar la uaad. It 1* filialat tha quantity of about 60 ag In flat oapeulaa of polyathylana with a oaTlty al-u «f (I 6 • x 3 • and wall thloknaea of about 0,5 am, or In oyllndrlaal oapsu- !las of FTXB with outar diaansloo* 0 5 «• * 15 •• and aarlty I I M M a x 5 at.A* for on* TL-raadlac tha diapanoar aeamiraa 15 ** of tha powdar, nomally thra*raadlngs arc takan of aaoh eapaula and thalr mean value la furthar rralnatva.

Tha raad-out of tha doaamtam la noraally dona bj lntagration of tha TL-elc-nal In tha "Autoaatlo ranga" aod*. Tha haatlug oyola, laatlnj 30 a, aoaprlaaa thaprahaat Intarral of «I»out 4 a, follawad by llaaar tamparatura rlaa at tha rataof 6.8 'O.a"1 fro* 65*0 «*» ta 240*0 (W«. 1 ) .

' If

• H*

• IU

• I—

•m

- 'SO

:: y•if S r t r

f

• •—^*\\' in'

/ ' \

ii

8uparpa«*d plata of thraa haatlagoyolaa atartac at dlffarant taapa-ratnraa

t (t) •

•~ Xaoordlmc tha flaw onrraa It haa saaa obaarraa that thajr era ahlftaa dapandanton tha tamfaratur* at wklah tha haatlag oyola la atavtat* Thla affaot apyaaraboth for TID-powdar (Kg. 2) and NB-raaa (Mg. ?)• A ohaak of tha haatlsg ayola

fig. 2Tlata of glow awrraa atartad at 30, 4050 °C af T1C-100 pawaar, nftni 2 Oy(eolU llnaa) aa4 1.S Oy (aaahad Uaa) .

UD-fOOrods

fig. yPlots of glow surras stoats* at 35SB* 50 *0 af TUM00 raas.

- 79 -

ahowad thai tha llnaar raglon la ladapandant of tha atart-tamparatura (fig. 1 ) .So It baoana naoeaaary to add tha atart-taaparatura aa a fourth paraaatar of thahaatlng ra'giaa. In ordar to ahortan tha oooling tin, tha atart-taaparatura hasboan flzad at 50 °0.

A ahlft batwaaa tha flow oarraa of TLD-powdar and TUJ-xoda haa baan obaarra*aa wall, obvloualy fiua ta waraa iharaal ooataat batwaaa tha rod and tha haatlacplanehat (Fie 4 ) . Xt la why dlffaraat llalta of lntagratlon of tha TL-aignal ha-•a baan ohaaaa - (110°, 210°)Cfor tha powdar aid <?2*, 236°)cfor rod*.

Ut'*d Fig. 4Olaw ourvaa of TLD-100powdar and TLD-100 rodj(O^Og) and (Of 0$) aratha oorraaponding integra-tion lntarvala

Tha oallbmtlon of thaTL-do»«m«t«ra haa baan do-ne In abaorbad doaa unltn,l.a* oOy, by Irradiationof aarlaa of doaanatarflIn a watar-aqulralant phan-tom with oobalt-60 gaiaaaraya la tha ranga froa 25up to 1000 oGy. Slight butimportant for cllnloal do-

40 so *t> re $0 te m HI ne ito i*t ifo it* .re itc m J°° *•> uo no2*0e;'C) *~

aiaatry purpoaaa auprallnaarlty haa baan obaerrad along th« whola oallbvation our-ra. Tha baat Bathaiiatioal approximation with oorralation ooaffloiant batter than0,9 haa baan obtalnad by tha formula 1L/HmtJ}+b, whara TL is tha raadlng for thaintagratad TL-algnal and D - tha abaorbad doaa In watar. Tha oonatanta a and barc of tha ordar of 10"^ and 101 raapaotlraly. Although a la rathar aaall, Itanaglaotlon by giving b tha rnaaa Talua of tha ratio TL/D would lntroduoa a ayata-E»tio arror of up to 6% at tha aarglna of tha calibration lntarral, nantlonad abo-y*. Suprallnaartty of tha aaaa axtand haa baan obaarrad with a TL-raadar of thaaama typa of tha Bulgarian 3SDL, but raoantly It waa raportad /3/ that thla aupra-llnaarlty diaappaarad, whan tha EL-algaal had baan intagratad by a Hungarian highpraolalon ourrant intagrator. So It aaama that tha magnltuda of tha doaa, aborawhloh auprallnaarlty aat« la, dapanda on tha TL-r«ad»r aa wall. Tola may axplalato aoma axtant tha dlffaranoaa la publithad data on thla affaot (1, 4).

An othar inatrumaatatloa affaot obaarvad with our TL-r«ad«r la that tha ptok-halgbt of tha t;low ourra laoraama appraolably with laoraaalng taaparatora rat a,but doaa not onaaa diffaraaoam la tha Intagratad TL-aignal (fig. 5).

rig. 5U o w aurraa of uniformly lrradlat«4 TUV-100 powdar, haatad mi dlffaraat tamparaturarataa (e)f in tha laaarta* tabla TL daaotaatha intagratad algaal.

1

234

e'C/i

2.84-2S.6

nSc

A.SS4.SSA. 60

180 2K>

9 CO2X»

- 80 -

Th« calibration of the TLD-100 powder for the radiation* ealtted froa the 42HaV Sieaens-Batatron revealed that th* calibration ourve for oobalt-60 gaaaa raysoen be dlreotly applied for the •valuation of absorbed doaa in water froa tha 43aT braaaatrahlung. For eleotrona, however, tha valuea raad fro* tha oobalt-60 oa-llbration ourra had to ba multiplied by a oorraotlon faetor k la ordar to obtalatha proper value of tha abaorbad doaa in water. Thie oorraotlon faetor seaas taba only Lightly energy dependant in tha range from 3 up to 32 KaT (Table 1), sothat lta aean value, figured out at 1,05, la raaaonabla to ba applied at all taeenergies,

Table 1.Multiplicative oorraotion faotor k to oonrart "oobalt doaa" to abaarbxtt doaa fromalaatroaa for HD-100 ponder

... ^ ...

lie?5.59.4

14.619.228.937.8

d

OB

1.02.03.03.03.03.0

Ka?

3.35.38.6

13.223.031.9

k

1.058*0.0041.065*0.0061.O59*OiOO51.051*0.0051.053*0.051.038*0.01 |

BQ - neaa anargjr at tha aurfaoaBd - aeaa energy at depth d

Lota of difficulties hara arlaan la attaaptlag to aeaaura einultameoualy doaeaalong an electron bean by a linear array of powder filled TL-do»enetera plaoed laa perapaz tuba separated by bafflt* of P«r*SOL (fla> 6). Suoh aaaauraaanta are

—'I —

08 <

If Sum «— -^f

ZpJM » 0

K g . 6Axial doaa diatributior.aof a 10 MeT eleotron beaa,mm weaaured with aa arrayof SWoaaaatara at dlffa-rant length (I) of tha par-apex holder eaerglng orertha aatranoe aurfaee of thephaatoa.

frequently aeeaatary wbaa treating tuaor upraada la tha vaginal wall by electronirradiation. First obaerred was tha affaot that If tha tuba eaergea orar tha an-traaoa aurfaoa, oonaldarable lower do»o Taluea are aaaauraa. Taia foroed ua tobuild a thlak walled tuba of parapax, 20 aa la dlaaeter, tha laagta af which i«adjuatabla to tha laagih of tha vagina (Kg. 7). Taa uae of this taba as taa do-saaatar haldar rasoltad, la tan, la aa avareatlaata af tha «•«• ta ba aaasarad<«lg. 7 ) .

81 -

20MtV\ 08*m

Jig. 7

Comparlaoa of axial doae dlatrlbu-

tlona of a 20 MaV »l«otron baaa,

aoqulrad froa lonlaatlos ohaabar

aaaauramanta and oorraotad for tha

anergy dapendanaa of tha maaa atop-

ping powar ratio (aolld llna), froa

a» array of TL-doaaaatara arranged

In tha thlok-wallad parapaz hoIday

•hem In tha lnaart (dashad Una)

and frea TL-doaaaotars, aach lrra>

dlatad aaparataly at dlffarant daptha

without tha holder (dottad liaa).

10

——— ionomttric*--—-TLD mmy intuit* *TLDtinfi* intmttr

To ohaok If tha aansitiYlty of

tha TL-doaamatara doaa ohaaga with

dapth poeltion In tha phantoa, aiag-

la doaaaatara of tha flat eapsula

typa hara baan lrradiatad diraotly

iamarg»d at dlffarant daptha In wa-

tar. Tha raaultad dapth doaa ourra,

"""" "" tha dotad Una in fig. 7, bad baaa

found to ba ahlftad by 1,5 am ooaparad to tha dapth doaa ourra drawn aooordlng

to lononatrioally datarnlnad abaorbad doaa raluaa. Hanoa, It aaaaa that tha aan-

altlvlty of tha TLD-100 powdar doaa not ohanga with dapth, but a aultabla dlapla-

oaaant oorraotlon baa to ba introduoad.

ObTloualy, tba dlaorapanoaa obaarrad with alaotrona ara parturbatloa affaota,

dua to both tha praaanoa ot tha parapax hoZdar In tha baaa and tha doaaaatar ar-

ray In it, whloh ara auob ooaplaz and hanoa dlffloult to orarcoma. Tba orarall

oonoluslon, that at praaent oould ba drawn la that with alaotrona TL-do«l««try ,

glraa auoh laaa rallabla lnforaatlon than with high anargy photona.

A aarlaa of 113 oallbratlon ohaoka, takan at dlffarant tiaaa during thla etu-

dy, ahowad that with tha aqulpaant oonaldarad in thla papar, a doaa of about 2

Oy of high anargy photon radiation oan ba aaaaurad with a daviatlon spraad of

± 2.5% and o.a.d. of 1.6* with TLD-100 powdar by taking thraa raadlnga of aaah

doaaaatar. With praaalaotod for uniforalty TLD-100 rods tho raoordad apraad of

tha darlationa la aoaawhat broadar, but atill within - 5%.

Oloaing, It is to ba aaphaslaad, that prarloua to atart ln-rlfo TL-doala»try,

tha propartlaa of tha partloulax TL-aatarlala and of tha raad-out aqulpaant ha-

TO to bo thoroughly axaalnad la ordar to oTareoaa tha pltfalla tbay alght pra-

aant.

Aoknowladaaaant a

Thla atudy la aupportad by tha IAEA (TA-ooatraot EUL/6/005). Wo ara thankful

to tha IAEA axpart, Mr. I.A.Laroh, PhD for hia auob balpfal adTiaaaant.

flafaranoaa

1. Rorowlta, Y.8., Phya.Mad.Blal., &, 1961, 765-824.

Z. t.C.R.O., Rapsrt 241 Dataralnation of Abaorbad B9»» la a Patlaat Irra41a>

tad by httmm of Z ar Oaaan Raya la ladlotharapy Proooduraa. 1010-Pukllaatloaa,

Vaah* OOii.0014, 1976.

- 82 -

3* Konstaatlnov, B., - personal commonloation.4. HoKinlay, A.P., Thermolumlnesoenoe Dosiawtry. Adam Hllger ltd, Bristol,

DOSIMETRY Of HEW 1 3 70AB8Ha 80CHCE8BEFORE THEIR APPLICATKBTTO CLIHICA1 PRACTICE

H.iiikori, V.Kuceo, H.StaakuaoYa:, K.Stopek, T.Sloao,Institute for Postgraduate Education la Medioiae and Pharmaoy,Radiotherapy Institute,Institute for Reeearoh, Production and Application of Icotopea,Prague, fiSSR

At present tlMa the exchange of braohyraaiotherapeutloal aoureaa from radiumto oaaalum la prorlded at radlotharapautloal departments togathar with an alte-rlnc approaoh to tha ••thoda of applioationa of thaaa souroes. Claasleal souroeswith 22^RJI ara not convenient In view of tha dimensions, energy and aapeolalljaa for aa th« risk of tha amanatlon of tha daughter produota la oonoeraed. ThatIs why they are gradually raplaoed toy "ce aouroaa both In lntraoarltary andlntaratltlal applioatlona.

Up to now l^Tsa' aouroe* hare oeen Imported fro« England (Aaerahaa) and appliedIn Halted uaa la afterloadlng Manual epplloatore. Bealdaa that new experience labeing obtained with two remote Seleotron-type afterloadlag eyeteas. Slnoe 1984137Cw oouroea la tha fora of naadlaa and tube* haya bean produoad la the Inetl-tuta for Reeearohe, Production and Applloatloa of laotopaa (tfvWR) la Fra-.tia. Theyara auppoaad to be dellyered to aoat of tha radlotherapeutloal departaa&t* la ouroountry. Slnoe 1985 twelre of theae aouroea - CMT-5 - type tuba* with nominal mo-tlrlty equal to 0,92 OBo, hare bean teatad la ollnlcal practloe la the RadiotherapyInetltute. Before their applloatlon In patlenta ollaloal doaloetry waa earrled oatla order to determine tha doaa diatrlbutloa laalda tha patlaat with preolalon oom-petleie to that of doaa eetlmatlon In teXetherapy.

In order to oaloulate tha doae, data lnfluanolng doaa dlatrlbutlon had to beobtained aad suitable mathematical model had to ba ohoaen. Tha ezperlMMe withtha doalmetry of the Engllah aouroea (type CDC-J)wae applied (1) to our aoureaaand ao enabled as to compare the parameters of the two typea. Tha baste paramatara (dimension and actinty) of aouroaa produoa* by tfTTTR ara Hated la tha tablain fig. It Th* axaot prooedure of tha produotloa of tha QHl- and CUT-type souroesla desorlbed la researoh report /2/| we mention only tha mala featuree. Tha aeti-re part of tha aouroaa la prepared by sorbtloa of l^Tca, aarrler-free solutioa oaaa •luBlaltac-alllooB baas. Tha Inner oelmlles of atalaleaa ateel ara filled withtha sorbent aad both - tha Inner aad outer - ara oXtsaa by atalalaaa ateel plugsaad welded by a plasma toroh la argom atmeaphara. Tha dlaeaalana preamatad la thatabla la K g . 1 axe eeaparable with theaa af Amarshsai ODO-J aai ODCI-J- type ««-tea, Th* ealy AlfftMM* la %U way af •laalag tht aallulaa a M «ha ttXUr M«a-rlal (tha ty«« OM-J vaiag flltera* »y aUtlaaa).

lealdea aaa^urlag af tha amtar aiaaulaaa tha ahaakiag af tka aaaatmatlaa fta-•lweea auiarailaciwyk* wmlah U aaavlaai with reaatgaaagrayhy af aaak anx—. Tha

- 83,-

CMJ 1

O J 2

(XT t

CHT 5

WT 6

CUT 7

ACTIVITY OIWNSICNS !m)

6 C

55,5

no220

550

920

1900

2500

15,5

25,5

«J,0

n.520,0

20.0

20,0

515

30

5.')

12

12

12

1,51.5

1,5

2.52.5

2.5

2.5

TUBE - CMT

3NEHDl.E - CMJ

B

A

Fig. 1Tha baalo paraaatara of aouroaaproduoad by

raaulta of auoh ohaoklac °* twalra CHT-5 aouroaa ara preaantad In fig. 2 whoaalowar part alaa glraa a oompnrlaon of th« aaaa plotura of tha Ra, , CDC-J endOP05-J tubaa. Tha alarodanaltoaatar UK III OS/Joyoa Lobal la oonnaotlon with a

mloroooaputar HP-9645 allowa to aaa-aura and dlgltallsa auoh roantgano-graaa. Tig. 3 praaaata an azaapla oftha raaulta of auoh proaaaalng of oom-blnad and alapla autoradiography.

Tig. 2Autoradiography ooabl&ad with raaat-ganography of twalra OMT-typa aouroaataatad la Radloftharapy Inatltuta. Intha lowar part of tha flgora tha aa-aa pleturaa of 2 2 6ta . CBO-J aadCDC5-J tubaa arw ahowa for aoaparl-aon.

• • •

• If

Frofllaa of danaltlaa of tha roantganograaaof CIO- typa tuba ottalnad by •lorodanalta-•atar MX III CS/JL oonnaotad with HB-9B45

Tha aotlrlty of tha aouroaa - la ra&g* 0.1 - 2.5 QBq - la araiaatad la aatra-logloal laboratory In tha Cum by a 49tjv- lonlaatlan ohaabar /3/. la that tinIt aarraa aa a aaaondary ataadardlaatlan lnetruaant whlah aoaparaa by aaana oftha ooapanaatlan aathod tha lonlaatlan ourraat of aaasurad aaapla with that ofaaoondary at*lon of tha 226Ra • By tala aathad It la poaalbla to aahlara aa aoon-

- 84 -

raoy of eatlnatlon of the activity of the tubes and needles better than i 3.5*

for the 99* confidenoe level. The aoouragy erf the measurement of the stiadard

10 better than - 2* for the 99* oonfldenoe level.

The quality of the souroes oould be laflueroed by the preaenoe and amount of

Impurities of the <134C* in the •ouroe. Thia la evaluated by Hpeetrometricol me-

thod and the amount of the i13*C_af doea not exoeed a value of 1* (but usually leaa)

of the amount of the Isotope 137cs7t depending on the quality of Input materials.

All parameter* above or* estimated by the produoere. In order to oaloulate the

doee distribution within a Bodel, other Input aouroe parameters hare to be supplied

a* well. In the Radiotherapy Institute we hare uaed two modele to oaloulate doaee

distributiont the RADCOMP model propoaed by Shalek and Stovall /*,/ li.planted In

an IBM-370 whloh has been used amoothly alnoe 1961, and Interval nodel propoaed

by Breltman /5/ whloh won adapted In 1984 for TI-99A mlorooomputer by the depart-

•ent of radiotherapy of the Inatltute for Poet graduate Eduomtlon In Iledlolne and

Pharnaoy /6/. Both programe allow to oaloulate the doee dlatrlbutlon fro« any li-

near eouroe providing that the Input parameters, I.e. aouroe dinenelone, absorb-

tlon coefficient* and value* of aetivlty and exposition or kema rate oonstonte

ar» adjusted for partioultr oaae.

W g . 4 - A, B (f»Bonatratea the results obtained by application of both aodels

for platlnlus) filtered CDC-J-type tubes /A/ and for steel filtered om-typ« tu-

bes /B/. The dose* whloh have bee* oaloulated on the ohoaen orosellnee ore plotted

in full lines fop Interval Model and in dashed lines for RADOOW model. The diffe-

rence among Models appears only in the region of the souree edges and in the oas*

of platlnus) filter /A/, for steel filtrated tubes /B/ the differemoes are leaser

than 2* for both Models. Similarly satisfactory agreesient was fownd with data po-

bllsbea- by Krlahnaswaaiy /7/ fer stainless eteel filtered tubee of the sajw oon-

etruotlen.

Tola faot la also deaematnted la Fig. 5 where doaa distribution oaloulated by

Aif if f M

•v 'I-rig. 4Ai Dose rates

•long orossllne*

calculated by In-

terval model (fmU

lines) and RADOOM*

•edel (dashed 11.

»•*), for tubes

ODO-J type flits-

red by platinum

with karma-rats

equal 7.2 Oy.i-1 _ Z

* •

(l.S.1 mg.sq.Bm).B« The same plotfor OHV-typs ta-les filtered bystsel.

XA9OO0 for stssl filtered OmT-ty»e twbss Is oos«mra« with vmlvas svtmtasc sy «sm-sitsmstrlsal evaluaUem sf sssssM rlias sy TksrMss tyatem. A eemporlm . f thesersMtu »i«. tM.t tn »TO-I *u ^*M tuksi filters* by •UtlmTis olss aiajbt It i s evlseat ttot tmm smallest dlfferemee betw«e« the tUMflaV astsl aa4sura* valmss i s seem fer sasalwa ssursss filters* by steel.

- 85 -

•CASUREO CALCULATED Fig. 5The aoaparlaon of oaloulated and aeaaurediaodoae ourrea around oaeaiua tub«a fil-tered by ataal and platlnua, and radluatubaa filtered by platlnua.

For aore datailtd etudy of tha lnflua*-oa of oonatruotion on doaa distributionalong tha longitudinal aouroa azaa thaaentloned ayatea of alorodenaltoaetar oon-naottd with tha HP aioroooaputar waa oaed.Tha obtained, profllaa of danaitlaa ia tharegion of tha enda of tha aooro«a ara pre-aantad is Tig. 6.

Howarar, froa ollnlaal point of riawtha influmoa of tha oonatmctlem of tta*aoureaa enda la not aa ai«nlflcant for ta«doao raluaa or doaa distribution aa taainfluanoa of tha type of filtration - mfalaa Fig. 4 A, B.

u.,-?2(- ( p'stlnun )

Fig. 6Prafllea of denaltlaa latka region of tha ana aftaa CDC-J - type tuba.

Conclualon

In oonnaotion with introduolng tha new Ciaohoalorak *~''Cm aouroea to ollnlaalpraotloa tha baala paraaatara of tha aoureaa were teated and tha reaulta ware faunato be satiafaotory aad ooaparabla with thaaa of iaarabaa aouroea. Tha ellnleal ax-perl enoe oonflnaa aa vnaaiblguoua aerlt af the aaealaa aouroea ragaadleaa of taalrproronanoa.

Raferenoeat

1. 2*8kova B.i Oaaalw-137 Daaiaatry Uaei 1* Braahytherapy. Ini Aktual.kllm.tnkol. 4, 1*2-165, BratialaTa, jda 1983.

- ač -

2. Stopek K., Duohíček V., žákova M.! Výroba braohyradloterapewtlok^oh aarlMa Ca-137 Y !ÍVWR. In! Kadioiaetopy, 27 (1). 31-40, 1986.

3. Drydk M., Chce J., Klta f., Mtal V., Zídek V., Xokta L.! 4jC^ionisagní ko-mora jako eou3áet ayat^mu aekundAmi etalonáie. Jaderná energie 2B, 11, 381-388,1982.

4. Shalek R.J., Stoval M.t Tha M.D. Anderaoa Method for Computation; of laode-ae Curvea around Radiation Souroea, Amer. J. oř Roaatgenology, 102, 3, 662-687,

5. Broltman K.E.t Doae rate T*bln for CHni#*l Oar 3onMM Sh**t*t lj* Pl^-ttnua, Brit. J. of Rtditl., 47, 657-664, 1974.

6. ZíSkoví H.t X<í<aí TÚ ILP, 1984/3.7. KriahMuwMty V.t Do<# Dlatribatloa ^bomt rt 'Oar Scureww la Ti##uw, Radiolo-

gy, 105, 161-184, 1972.

HEAVY CHARGED PARTECH DOSIMETRX.AZDAPFHCATIOZ

Johnny W. Hon<#aRi<^ W^tlon^l Laboratory. DX 4000 Roaklldw, D<n<Mrk

For *h# **a* aaouat of r*dl*tloa do#<, phytiotlly dlff*r#at radlattoa fioldaproduo* quantitatively different effoota for the eaae ondpolnt.'a phenomenon whiohla due to heterogeneity in looal energy dopoaltlon. A oen,tral problem in radiationreeeareh with heavy lona ia trying to underatand and correlate the ohemioal andbiological effeota prodnoed by the radiation in terata of phyaloal and awbaequentchemiaal chattgea that take plaoe. Traok etruotvye oaloulatlona can in principlebe uaed to oaloulate In completa detail the phyaloal energy depoaltlen dlatribn-tlon around the path of a heavy ion an* the aubeaqwent ohemioal ohangea, and offer*a* ouch a powerful anaiytle Seal for tttaeMmg a very Important problem* We havedeveloped a eomputer zadoi to ealeulate tha paaaaga af a heavy eaergaa pavtl<Haamd ita effaot la different tiaaue aqulvaleat me4i<*. Experimental and theeretloaldata are preaaa*a^ ef different radiationa ia the amlae aoid L- ee-alanina, whloaia form of a tlaane equivalent pellet haa turned out to be a very ueeful radiationdeteotor In low- and hlgh-LZT radiation flolda. The electron apla reaonanoa read-out teohnique la aon-deatruotive with reapeet to the moaeureA algaal and the naa-ful doae range la at preaent from 0.1 to 10^ Oy. The low-LET radiation laducoffree radloale are extremely atabla over a long period of time after doaaa belowapproximately 3.10* Oy. But fading of the radiation induced roaponee haa been oa-aorvod after ezpoaurea to hlgh-LZT radiatioaa aad to vary high deaaa of lew-HTradiation. Tha doaamatar ia auitable for iatareallbratiea of radlatloa faolMtiaa,for oontrol and dooumaatatlon of therapy doaaa, aad aa a paraonal aoeidant Aoaa-meter for radlatloa workara.

Heavy oharged-partlela radiatlea therapy im tha,traatmaat of aaneer diaaaaaala a praetleal reality, aad it ia a matter of faat that mora haapltal* will addto tma Hat af inatitmtea havlag faoilitlaa iaatallaá for raliotharapy áy maamaaf aithar faat protoma, #^-partlalea, aeu*#oaa, ar hlgh-HM martlolaa. Tha aaaiafar theae laatallatloma ia that wa have a better wndarataallag af heavy aaargadpartiolaa H yraatiaal all*la*l appliaatlama, thera ia a aaatw for aatialmatiHgm aliaiaal gain fram iapravaá daaa diatriawviatt, amá thara ia * g*i* **** * **-

- 87 -

duction in OER of tumor cells. But radiation therapy with charged particles also

calls for reliable dosiaetry.

One of the central problems of radiation research with heavy charged particles

is to understand and correlate the effects produced by the radiation in terms of

physical events and subsequent chemical reactions that take place. And it is well

known that for the same amount of radiation dose, different LET radiation fields

produce quantitatively different biological and chemical effects for the same

qualitative endpoint. We know that the RBE can be as high as 50 for biological

systems and as low as 0.01 for physico-chemical radiation detectors, depending

on the absorbing medium and the charge and velocity of the penetrating particle.

This means that a factor of 100 can be caused by the track structure differences,

the interpretation of which cannot be made without the help of a theory for track

structure (1-3).

The theory of track structure has shown to be able to calculate the physical

energy deposition distribution around the path of an ion and to correlate the sub-

sequent chemical changes (4,5). The theory offers as such a powerful analytic tool

for attacking a very important problem in radiation dosimetry and research with

heavy charged particles.

In our laboratory we have been working on a computer model which calculates

the passage of a- heavy charged particle and all secondary electrons through the

initial physical stage of Interactions in different tissue equivalent media. The

model, however, does not consider the chemical evolution of primary and subsequent-

ly formed radicals, but incorporates in the calculations the chemical endpoint at

different doses obtained from experimental data for photon or fast electron irra-

diation of a medium. By means of the model response from a single ion or a fluen-

ce of ions can be calculated step by step as the ions penetrate into the medium.

This medium could be cell cultures, human tissue, or radiation detector materials,

for which we know its low-LET characteristics when irradiated from low doses and

into saturation doses.

The theory has successfully been able to calculate survival curves, RBE, and

OER for different biological systems as well as dose-response characteristics for

radiation detectors (6). we hare in our laboratory improved the theory and in ool-

laboxmtion with other laboratories tested the theory against measured data from a

few physico-chemical radiation detectors.

Dose-response characteristic* of an amino acid, L- <£-slanine, have been ob-

tained for • number of different low-LET radiations for which alanlne shows the

same radiation sensitivity in the dose range up to 10* Gy. These radiation quali-

ties were the following: °Co y-rays, 4 and 16 IW x-rays, 6, 10, and 20 MeV elec-

trons, Pig. 1.

Pig. 1

Dose-response of alanlne exposedto: 60Co jM-ays, 4 and 16 11V x-rays,6, 10, and 20 MeV eleotrons

1010' icr 10Dose |Gy)

- 88 -

Dose-response characteristics have been obtained as well for high-IET radia-tions covering a range in initial LET ot 3 to 2000 keV/<u.m, Pig. 2. As a gene-ral rule and in aooordanoe with the basic theory the radiation sensitivity of ala-nine now decreases with an increase in initial LET tims, reflecting the effective-ness, RE, of heavy charged particles in. producing tree radicals per unit dose.

AESR/g Dose response of AlanineJig. 2Dose-response of alani-ne exposed to: 1) low-LET radiations* 2) 16MeV protons* 3) 6 MeV

0.25 --to various radiations.

1. Low-LET rodicttor2 16 MeV protons3. 6 MeV protons4. 20MeV a. -part.5. 21 MeV Li - ions6. 7i0 MeV "Ar - ions7. 64 MeV '60 - ions8. 80 Me1.' 3?S- ions

0C5-

protons* 4) 20 MeVparticles| 5) 21 MeV'Id-ions; 6) 740 MeV40Ar-ions* 7) 64 MeV1S-ions, and 8) 80 MeV32S-ions

1-1CT 2 10J•Gy

Troio the measured dose-response charaoteristlcs for alanine irradiated withlow- and high-LET radiation* experimental RE-values were obtained. These datahave been successfully compared with predicted data from the track atruoture theo-ry, Table 1. The biggest deviation between measured and calculated data are foundfor the ions of lowest velocity, all of which are stopped in the target material.Calculations In the Bragg-peak of the stopping ions are awr* unreliable becauseof uncertainty on stopping-power data for low-energy ions and radiation effective-ness of very low-energy electrons (7). It should be emphasised that the decrease

Table I

Experimental values of RE for alanine compared to calculated RE

16

6

20

2\

7«0

bk

80

Root

MeV protons

MeV protons

MeV a-particles

MeV 'Li-ions

MeV "°Ar-ions

MeV "0-ions

MeV "S-ions

27

68

1026

786'

52711

20200

mean square deviation

L"init.

Mevcn'/g

1.00

0.86

0.58

0.37

0.37

0.32

0.2b

RE<

0

0.

0.

0

0.

0.

0.

:xp.

99

85

60

1)0

36

3'23

REca

-1

-1

•3

•6- 1

-3-8

1

10.

.0

%

. 2 i

.1 '

.1

.511

.0

.8*

In RE does not neoessarily follow an increase in LET. As for example the 740 MeVAr-iona and the 64 MeV 0-ion«, where the argon Ions have the higher LET and

the larger RE. This indicates the complicated nature of the relationship betweenRE and LET of the particle, which, however, the theory accounts for.

For practloal application in radiation dosimetry the crystalline L-«t-alaninepressed into pellets has shown to be very appropriate as a radiation dosemeter(8,9). The radiation Induced, free, and very stable radicals are analysed by meansof electron spin resonance, ESR, speotrosoopy, and the relative measure of radi-

- 89 -

cal concentration is used for dosimetry purposes. The dosemeter is mechanically

robust and easy to handle, and the read-out technique is non-destructive with

respect to the measured signal. The useful dose range for e.g. low-LET radiation

and for a pellet, 4.5 mm in diameter by 2 mm in thickness, is from 0.5 to 10^ Gy

with a linear dose-response relationship up to 10* Gy. By measuring four pellets

at a time or by having a 8 mm long rod of alanine the lower detection level can

be decreased to 0.1 Gy. The overall uncertainty of the dose determination Is

ii.12% at 95;1 confidence level (10).

Fading of the low-LBT radiation induced radicals is for doaes below 10* Gy less

than 1% per year for samples kept at normal laboratory conditions, but above 10*

Gy more pronounced fading has been observed, Fig. 3.

{ 7: - C : T ; Z'. response after exposure to Co Y-rays

•O'Gy

of response for alanineexposed to Co jt-rays to dosesof 104 and 5.1O5 Gy

300 500 700 •iCCO Hours

For alanine irradiated with high-LET particles to average doses below 10* Gy

some fading has been observed as well, e.g. 355 In 4000 hours for 16 MeV protons,

and it turns out that the degree of fading depends on the LET of the particle.

The higher the LET, the higher degree of fading. After exposure to saturation do-

ses with stopping 21 MeV lithium ions a fading of approximately 20% has been ob-

served after 4000 hours, Fig. 4.

* % Fca—g :' 'esponse after exposure to hgh -LET icrs

Fig. 4• -- Fading of response for alanine

exposed to high-LET radiations

of 16 MeV protons and 21 MeV

'Ll-ions to doses of 10* and

5.1O5 Gy

20 r21VeV

100 300 500 700

In many respects, typically for slow particles, it is reasonable to expect dif-

ferences in the chemical reactions going on along an area close to the primary

particle path. In this region the radicals are formed very closely to eaob other,

that is why the reactions may be different from those in the thin-down region of

delta rays at larger distances from the ion's path. From the point of view of ionl-

zation density and consequent radical concentration there is some justification

in calling the area close to the ion's path a track core. The concept of core and

penumbra is meant to apply to the condensed phase of the medium, i.e. liquids and

solids. At high energies and low charge of the ion the energy loss events are more

apart and in that situation a core may not actually exist, Fig. 5. Thus the con-

- 90 -

o«pt of core ia rather a high-LET phenomenon. Penumbra refers to the thin-downregion of delta-ray tracks perpendicular to the Ion'a path.

Fig. 5Simulated tracks of protons and -partlole* of various energies showthe ionization density in the tradeto tie a function of particle veloci-ty and charge. (Hansen et al.)

«O H*V

of the particle energy is dieThe same calculations for a 21 MeV Li-ion yield

A high ioniiation density leads to a high concentration of trapped radicalswhloh, however, in organio solids cannot stabilise closer together than approxi-mately 10 • according to published data (11). Excess radicals, formed either byhigh doses of low-LET radiations or in the traok core of high-LET particles, willreoombine until an equilibrium la obtained. The recombination kinetics is observedas a measured fading of the response. At a dose of 105 Gy, which is in the satu-ration range, an average distano* between neighbouring radicals is theoreticallyfound to be 0.6.10 m. At a dose of 5.1Cr Gy the average distance is 0.3.10 m,which Is a factor ot three below the distance considered to be the minimum distan-ce for stabilized conditions. Calculations show that in the traok of a single 16lieV proton passing through a thin alanine targetoipated at doses above 105 Gy.31%. Hence, fading of response after exposure to high-LET particles may be ex-plained by the high local doses occuring in the ion's track.

At the very high doses already formed radicals are transformed further intoother species, which can be seen from a comparison between obtained ESR-epectraof alanine Irradiated with low-LET radiation to a low dose and to a saturationdose, Fig. 6. A comparison between ESR-speotra obtained for alanine irradiatedto a low average dose of fast electrons and oxygen ions also reveals a differen-ce which points to the existence of saturation effects in the track of a heavilyionizing particle, Pig. 7.

Pig. 6ESR-spectra of alanineexposed to 10* and 5.10^Gy of low-LET radiation.A comparison between thetwo spectra reveals thatradicals formed at lowdoses tend to.disappear

Exposure toiOMeV electrons a t saturation doses

.1'OSL' 10" GyDose S-10'JC,y

tr.utiiralion ••

- 91 -

Exposure tolOMeVek-ctrons ] t i

Exposure 1o64 MeV 0 -ions

Fig. 7

ESR-spectra of alanine exposed to a low dose of low- and high-LET

radiations. The increase in the ratio of A^/B^ points to the exis-

tence of saturation effects in the track of a heavily ionizing par-

ticle

These findings indicate that different chemical reactions are talcing place in

the track of a high-LET particle at different distances from the ion's path, and

that it is reasonable to consider the chemical reactions to be dependent on ioni-

zation density. But the kind of chemical reactions in the track of a heavy char-

ged particle will be the same as if the medium was homogeneously irradiated with

low-LET radiation to the same ionization densities.

In conclusion our investigations have shown that alanine is suitable as well

for use in high-LET dosimetry as the relative effectiveness decreases by only a

factor of 4 over a LET-range of four orders of magnitude, and because the dose-

response maintains linearity also for the very densely ionizing particles. Further,

dose-response of alanine closely fits the conditions for the theory of track struc-

ture for heavy charged particles, which makes the relative effectiveness and thus

the dose-response for high-LSI radiations predictable. But for use in high-LET ex-

posures fading of response must be considered even though the dosemeter has been

exposed to a low average dose.

In addition, however, alanine presents a very useful dosemeter in radiotherapy

in respect to: intercalibration of low- and high-LET radiation units, in routine

dosimetry, for documentation of dosea given to patients, and ee a personal acci-

dent dosemeter for the clinical staff and for radiation workers in general.

References

1. Katz, R., Sharma, S.C. and Homayoonfar, K., The structure of Particle Tracks.

In: Topics in Radiation Dosimetry, Supplement 1. (F.H. Attix, Ed.) 317-383. Acade-

mic Press, New York (1972).

2. Olsen, K.J. and Hansen, J.W., Biological Effectiveness and Application of

Heavy Ions in Radiation Therapy Described by a Physical and Biological Model. Ri-

s^-R-477, Ris4 national Laboratory, Denmark (1982).

3. Hansen, J.W., Experimental Investigation of the Suitability of the Track

Structure Theory in Describing the Relative Effectiveness of the high-LET Irradia-

tion of Physioal Radiation Detector*. RisjS-R-507, Ri«S National Laboratory, Den-

mark (1984).

4. Hansen, J.W. and Olsen, K.J., Experimental and Calculated Response of a Ra-

dioohromic Dye Film Dosemeter to High-LET Radiations. Radiat. Res. 21, 1-15 (1984).

5. Hansen, J.W. and Olsen, K.J., Theoretical and Experimental Radiation Effecti-

veness of the Free Radical Dosemeter Alanine to Irradiation with Heavy Charged Par-

ticles. Radiat. Res. JhO£, 15-27 (1985).

6. Katz, R., Track Structure Theory in Radiobiology and in Radiation Deteotion.

- 92 -

Nuolaar Traok Dataotlon 2, No. 1, 1-18. Pargamon Praaa, Haw York (1978).7. Olaan, K.J. and Hanaan, J.W., Sxparlmantal and Caloulatad EffaetiTaaaaa of

a Radioohrotnlo Bya M i a to Stopping 21 MaV 7Li- and 64 MaV 16O lona. Huol. Xaatr.Math. B5, 437-504 (1984).

8. Ragulla, £.?. and Seffaar, U., Doaiaatry by ESR Spaotroaoopy of Alanlna, Int.J. Appl. Radiat. Iaot. 22. 1101-1114 (1982).

9. Banana, J., Da Choudana, H. and Daaoour, S., Applioation a la Doaiaatrioda la Haaura par Raaonanoa Paranagnatiqua Blaotroniqua daa Radiooaux Libraa Craamiana la* Aoldaa Aalnaa. In: Adranoaa la Phyaloal and Blologloal Radiation Datao-tora, STJ/PtJB/1269, IAEA-3M-143/50, 311-325, Vlaana, Auatrla (1971).

10. Raaaan, J.W, and Olsaa, K.J., Oataotloa of Low- and High-LET Radiation withAlanlna (to ba publlahad).

11. Elliott, J.P. and Wyard, S.J., ini Sffaota of Ionising Radiation am M A .(J. Httttaxaaan, W. Uhnlain, and R. Taoula, M « . ) , Oh. 5, 80-86, kolaoular Biala-gjr, Bleohamlatry and Biophyalaa. 27. Sprlngar Tarlag Barlia, Haidalbarg, Haw lark(197B).

PAS3IVB PBTECT0R3TOR FAST JEUTROH THBRACT BH

VrantiBak Spurn/,Inatituta of Radiation Doelaatry,CcaehoaloTak Aoadaay of Solanoas,Ma TruhWfoa 39/64, 180 86 Praia 8

Abftraoj

Ihara ara many doalmatrlo problama whloh hava to ba raeolrad la oonnaotloa withtharapautloal ue» of faat nautrona. To obtain aoaa additional data on, a.g. ln-phantoB doaa diatribuiioca, baaa hoaoganaity, ato., alao paaaira dataotora oaa aauead with anooaaa.

Tola work daaorlbaa tha poaalbllltiaa of thaxvoluadnaaoant and aolld atata no-olaar traok dataotora (.113) and SaBTD). Plrat, baalo oharaotariatloa of TXD an*SSXTD atudlad by tha author ara daaortvad, l.a. thaIra raaponaaa to faat nautrona,la tha oaaa of TID'a alao ralatlvaly to gaana raya alwaya aoooapanylng faat nautron*.Tha poaalbilitlaa of their uaa la radlotharapautio faat nautron aaaaa ara outllaad,aoaa partloular problaaa and quaatlona ara dlaouaaad.

I. Introduction

Xautrona ara of graat lntarast for radioblology and radiotherapy alaoa tha/ of-for th« praotioal poaaibillty of azpoalag blologioal objaota or tuBoux* tc tha ra-diation with hlghar llaaar aaargy tranafar and with a ralatlraly ooaTanlaat dapthabaorbad doaa dlatrlhutloa (1,2). 1Tha aoat aoourata and tha moat praolaa aathodto aaaaura tha abaorbatf doaa In a nautron baas la tha uaa a* yaira* ionlaatloaohaabara. Oaa of thaa, oallad "tlaaua-aqulralaat" aaaauraa total abeerbad doaa,l.a. dua to naatrona aadt alao, pbotona alwaya praaaat la a nautrm baaai. Tha *•*oond oaa la ganarally aada of a non-hydrogaa oontalnlag aatarlal. Ilka graphita,altartnlm ato. it oharaotariaaa aoatl^ gaaaw ooaponaat of a baaa (far tatall dia-

- 93 -

ouselon ace, for example /3-5/).Xevertheloaa, they art aaay doeiaetrlo problems whloh oould be solved also by

aeaaa of other typea. I.e. paselve deteotora. Ihla work deaorlbea the poaalblll-tlaa of theraolualaeeoeat and solid etata nuolear traok dateotora (TLD and SS1TD).Baslo doalnetrlo oharaoterletlca of aoae of thaaa dataotora are deeorlbed, on th«tothar hand aoaa example* of their uaa mv* glvaa.

II. Siparlaantal data.HaII. }.. Sataatora

SID'a and SSISO'a atudlad ara obaraotarlsad la Tablaa 1 and 2.ILD'a war* rraluatad gaaarally with a ?ltaaa 654 TOIBDO reader, praheatlkc and

heating teaparaturaa ara aentloaed la Table 1. Heutron Irradiated dateotora werealvaya aralaated toc4tber with dataotora of tha aaaa type calibrated with °Coradiation.

Table It Tharaolualneaoent deteotora atudled

TUD

dlaoa ( 0 . 8 | « ) l )

OaSO i Eyi powder or tef-lona(0.4,13)-5* of TLD

'U' t powder or alntareddlaoa (0,85*4.5)

Alujaophoaphate glaaa(1.00| 10)

Ta»»eratura /X/»f

preheating

423

433

-

heating

543

523

533

653

MinimaldateetaUatlaeuekeraa/mtl-m/

10

0.01

0.01

0.01

l3The flrat figure - tha thiokneaaj the aeoond - tha dlaaeteri both la ••

SSBTS'a ware etched la tha oondltlona praaantad la Table 2, In eoae eaaea aleoaleotroohemloally (MELHTKI 0, OR 39, CH 85). They were generally traluftted by aeaniof aa optical aloroaoopa (for eleotroohemloally etched apota with an projectionaoreen) at aagnlfleatlone batweea 200 aad 600 tinea.

Reaulta of tha evaluation were for both TLD'a and SSBTS'a atatlatloally ela-borated aad will be preaented with their unoertalntlea at the 95% oonfldenoc le-vel.

II. 2. Irradiation*

To eetabllah thalr reaponaea to faat neutro&e, TU)*a and SSHTO'a were Irradia-ted la the beaaa of different aouroea of aonoenergetlo and polyaaargetle nautroaa/6/. The oharaoterlatloa of a beea were generally eatabllahad ualng the,ayateawdeveloped by looal ataff (for exaaple - long nountara, lonlsation ohanbera e t c ) ,la aoaa etmam, tha author waa able to perfora hla own aeaauraaanta with loalcatloaohanbera deaorlbad above /3-5/.

All dataotora ware Irradiated by aoraaly inoident aeutro&a* TID'a ware alwayaoovered with a aaterlal aaaurlag tha aqulllbrltanof all aaooadary charged partlo-laa.

- 94 -

Tabl« 2i Sol id atata nuolaar traok dateotor'a atudlad

35HTD

Ca-Ba aloroaoopa glAos- ln ooataotwith f laaloaabla aa.tarlal*(Th, 0 , Bp)

Polyeatar H S U m Q-ia ooataatwith flaalonabla aatarlals(Th, 0, Hp)

Polyaatar HSLIRX 0

Allyl dlglykoloarboaata OS 39

Calluloaa aJLtrat* KODAK 01 85

Calluloaa altrat* KODAK LR US

Stahlag •ontttloa*

}0% HP, 298 Z

30* K0H# 343 KllRr.om"1! 5 kBa

30* KOB| 343 X40kV.oa~1, 5 kB»

30« KOH, 343 k>293 K, ZSkT.OB"1, U kBs

5.51 KOHi 323 K «a4UICT.OB"1 , 5 kH«

2.51 M0H| 313 K

I I I . ReaultaiI I I . l . Tha f fFVP** to

Lat Kg and Kg ba tha karaa la tlaaua du* to faat aautroaa and gaaa* radlatloa,raapaotlraly, la a nautroa baaa. Lat R ba tha lualaaaoant output araluatad la adattotor irradlatad la thla baaa (R la axpraaaad la baaaa of tlaaua karaa. of 600orafaraaoa gaaaa radiatloa). tha ralatlva raapoaaa, RR. of a TLO to fnat aautroaala th« baac la* th»ntof aqual toi

R - KgRH (1)

Suoh quantity ahowa, to what aztant TLS'a oaa glra aa lnfon»t ioa ooaoanlnc thanautroa oonponant la • baaa. It la known that tha ra lat lr t rvapeaiaaa of th* aoatof TLD's to faat nautroaa *ra ganaraOly low / 6 - 1 1 / . In * alzad nautroa-gawu baaatiay ara tharafora uaad to aatabllah tha doalmatrlo obaraotarlatloa Mainly of thagaan* oomponaat. Kararthalaoa, to do It oorraotlj , faat aautroo ralatlva r*apea-w*m ha* to ba known. It not, aarioua arroxw oan ba ooiBBlttad 1 ^ .

Paat nautron ralatlra raapoaaaa of aoaa TLD'a axa praaaatad la Tasla 3 , thaywara aatabllahad for dataotora oorarad wy hydrogaa non-oontaiming «atarlala, aoat-ly by taflon. Cba oan m»» thara that tha ralatlra raapoaaaa «r# in ganaral ra.tha>low, aapaolally for nautrona with anargiaa balow about 5 M«T. Bowarar, araa lathaaa oaaca, aaeaaaary oorraatloaa axa not alwaya nagllgibla. for azaapla, for3.3 U«T aautroaa produoaA at a Van-da-Oraaff aooalarator fey D/D raaotion, gaaawbackground x*tr*mtm about oaa pir oast of tlaaua karaa. Taklag lato aooowt tharalatira raapoaaca glran la Tabla 3, nautron oontributloa wi l l ra»raaaat featwaamfifty aad aixty alz par oaat of total tharaoluaiaaaosut algaal. of oouraa, forhlghar nautron anargy aad at low gaaaa oontrlbutloa, thaaa oometloaa- wi l l b*• t i l l mor* laportaai*

Thara la aaotha? factor whloh haa to ba takaa into aoooxait wkaa TU)"a ar«»• y — dataotora la a nautroa baaa. Yraquaatly, thay aro Mat with aoaooatalnla& hydrogaa. I t oaa lafluaaoo tha ralatlva raapoaao »ary araajitloaUy.SOB* azaaplaa of auab affaot ara daaoaatratat la Tabla 4* thay ara TallC fa* a

- 53 -

powdar TID'a praaantad In T«bla 1 . On* oan aaa that in aoaa c u n , TLD'e raapoadato faat neutron* l a t a n u ef tlaeua karam praot ioa l l j u to suamaa. In aueh aaaaathalr uaing aa caaaa dataotora la T « I 7 l l a l t a d .

Tablt 31 Paat nautron ralatl/ra raaponaaa of aoaia TLD

/MaV/

0.7161.40

a.io1*3.304.201>4.401)

5.256.2O1'7J001'

14.715.119.0

i i 2 o >

0.008*0.0010.014*00.011*00.052*00.011*00.022*00.056*00.073*0.0.170*0.0.200*0.

-

.007

.003

.013

.006,009.013009015020

Ralatlra

0.002*0m

0.011*00.011*00.031*00.030*00.033*0

4

.001

.007,002.012,010.010

0.045*0.0110.063*0 0090.096*0.0080.100*0.0.170*0.

010020

racponaa7 U f

0.012*00.006*00,020*00.015*00.052*00.056*00.029*00.057*00.069*00.100*00.110*00.180*0

of

.003

.001.017.002.013.006.011.047.009.010.020.020

000

Al-P (!•••

.020*0.010

.020*0.008

.043*0.0120.040*0.0150000

.029*0.011

.047*0.012

.054*0.008

.100*0.010'_

-

'Poljranargatlo nautron aouroaa

Tabl* it Xnfluano* of poljathrlana p«oklng on fact nautron ra la t l ra rcaponaa of• o n TLD'a / 1 2 /

TLD

A12O3

o«so4

7uf

Al-PClftaa

Prcklxf

run1*

PTTKrt

pmn

RE to fMt nauAvosa wit a 8^f /MaT/4.2

0.052*0.0130.406*0.037

0.031*0.0120.278*0.01*

0.012*0.0130.125*0.026

0.043*0.0120.112*0.013

6.20.056*0.0110.335*0.032

0.045*0.0110.261*0.020

0.057*0.0190.160*0.014

0.047*0.0120.119*0.010

7.0

0.073*0.0090.456*0.028

0.063*0.0090.320*0.022

0.069*0.0090.213*0.013

0.054*0.0080.133*0.007

14.70.17*0.020.96*0.06

0.10*0.010.52*0.05

0.10*0.010.38*0.04

0.10*0.010.90*0.06

1)P O T - polytatrafluorathylana (taflon)FB - polyathylana

III. 2. tha raaponaa of 33HTD a to faat nautrona

Tha raaponaa of a SSHTD to faat nautrona la ganarally axpraaaad In taraa oftraok nuabar par ona noxaaly lnoldant nautraa.

Aa far aa SSVT&'a In oontaot with flaalonabla matarlala ara oonoarnad It waaprorad alao by our atudlaa /6/ that thalr raaponaa la dlrootly proportional toflaalon oroaa aaetletu Tha oonatant of proportionality waa found out to ba aqualtc 2.9x10"* for «a-O» glaaa and 6.0x10"* for U L X R X 0 (aaa Tabla 2)# In both aa-aaa axpraaaad in taraa of traok aaabar par ona nautron whan flaalon oroaa aaotlan

'it la alao Talld for thaiaal nautrona. lararthalaaa, thaxwal navtron laportaaaala radlataarapautla baaaa la not too graat and TLD'a dlaouaaad la thla work arala canaral Uttla aanaltlra to tharaal nautrona.

- 96 -

is equal to 10" m (1 b a m ) . Prom this valua It follows that, for example, the

response of MELUJEX 0 In oontaot with ^ Th to 14.7 MeV neutrons (cross ••otlon

4x10 ° m ) la equal to 2.4*10 tracks par one normal Incident matron. The res-

ponses of SSNTD's without a fissionable material to faat neutrons are presented

in Figure 1. One oan see that both absolute values as energetical dependences dif-

fer greatly from one detector to other, for example:

Figure 1:

Response of BOB* SSNTD's with-

out fissionable radiator* to

fast neutrons.

1-CR 39-ccnrereC by PI* chemicaletohlng (CE)2-CR 39-eoTered by PBj e leotro-chemloal etching (ECS)3-CH 85-ooTered by PKj BCB4-LR 115 a l l tracks» CE5-MELIHBX Of ECB6-LR 115 holes; CE

o

a>

a.•j)

a

id*

id8

^ ^ - ^

_-—•— -—.

0,1 10

EN,MeV- The most sensitive SSNTD as fast neutron detaotor Is chemioally etched CR 39

material;

- This material, both chemically and electrochemlcally etched, as well as electro-

chemically etched oellulose nitrate KODAK CH 85 material responds sufficiently

even to fast neutrons with energies below 1 ItaTf

- Other, proton nonsensitive SSNTD, responds only to neutrons, with energies su-

perior to 1 MeV{ in some cases (through etched holes la LR 115, eleetrocheml-

cally etched ll^LXHKE 0 as reooil particle detector) the energetical dependence

is very steep.

III. 3. Application

First, it would be useful to precise dose limits of application of both types

of detectors in fast neutron therapy beams.

Minimum detectable tissue kermas due to gaama radiation are for TLD used In

our studies given in Table 1, they are sufficient for our purposes. As far as the

highest detectable tissue kermas are concerned they are for all detectors studied

of the order of 10 Gy. For higher doses a saturation Is gradually reached.

As tax as SSNTD's minimum detectable dose depends not only on the deteotor's

response, but also on the own background of a detector; they oan vary also with252

neutron energy. If one takes as the examples ' Cf neutrons, reap. 14.7 MeV neut-

rons; minimum detectable neutron fluencea are for both of the order of 10 « .

It corresponds to tissue kermaa of the order of 0.1 mGy. The highest detectable

fluences are limited by track overlapping, they are la general of the order of

10 Gy. Also these limits correspond well to the denands of radiotherapy neutron

beam's dosimetry.

As mentioned In the introduction, passive detectors are particularly conve-

nient for ln-phantom dosimetry measurements and experiments. As an exaaple, we

present in Figures 2 and 3 depth dependences of track densities in SOB* detectors

irradiated in phantom in the beam of neutrons produoed at U 120 cyclotron by

- 97 -

Depth dependences of track den-alt} In some SSBTD irradiatedIn the beam of neutrons produ-ced at U 120 cyclotron (M^ 6.2MeV) - 1

A - Ha-Ca glass In contaotwith 232Th»

• - chemically etched CH 85• - chemleally etohed LR 115

neutron dose establishedby means of lonleatlan c tubtr i

60 160 240

Depth in phantom; [mm]

Pig. 3Depth dependences of track den-

sity in some SSNTD irradiated

'iO.J in the beam of neutrons produ-

ced at U 120 cyolotron (BjJ 6.2

Hs7) - 2.

id - Ha-Ca glass in oontact

with e n rU

D - through etched holes In

chemically etched LR 115

neutron dose established

by means of lonization chambers

X - intermediate neutron fluen-

oe

°Be (d, n) reaction (E^ 6.2 MeV). One can see that in some cases the track den-

sity vary with the depth in phantom In the same way as neutron dose established

by means of ionlsation chambers. Such detectors can be well used because of their

small sizes to solve rather complicated in-phantom measurements. For other detec-

tors (see e n rU - Fig. 3) track density depends on depth in the same way as the

Intermediate neutron's fluenoe doses. In some cases also such information can be

useful.

References

1. "Neutron Doaimetry for Biology and Kedicine". ICRU Report 26_, ICRU, Washing-

ton 1977.

2. "K vyuzitf elementarnxch castic v lekarstvi a biologii"red.: J.Sedlak, J.S&-

oha, lA.L0Sie.3ic.ek, y.Spurnyj Izfi CS&V a SAV, Bratislava 1979.

3. Spumy, F. - Votockova, I.: Jaderaa energie 2_2, (1981), s. 434.

4. Spumy, F. - Votockova, I.: Jaderna energie 28, (1982), 3. 81.

5. Spumy, F.: .Jaderna energie 28, (1982), s.219.

- 96 -

6. Spumy', 7,\ "Hetody doslmetrle mijiiho oztxtni a Jej icb pou i l t i" . Doktor-sfc* dl««rtaSnf pra"oe, Fraha, kreten 1964.

7. "Heutron Doalmetry for Biology and Medicine". ICRO Report Ho26, ICRU, W«s-hington 1977.

6 . Spurn?, 7 . - Medlonl, R.- Portal , 0.x "Jadern* energle 2J, (1975), a .415.9. Furuta, E. - TanaJca, 3.x in Proo. 4th Intar. Conf. lua ln . Doala., Krakow

1974, v o l . 1, p .97 .10 . Hennljfer, J . - BOoner, K. - Pretssoh, O.i Xuol. loatrua. Math, i ^ i (1982*

P. 453.1 1 . Oibaon, J.A.B.i "The r t l a t l r a tlc«ua-lcanu aaaa i t i r l ty of thamolualaaa«ant

matarlalas A rirria» of arallabla data". CIHDOS Raport, Saoaabar 1984*12 . 8puntf, V.i R«dlat.Prot.Doal«. 2 , (1984). p.257.

SLOW MBUTRQN JLllX DISTRIBUTIONIB PHAMTOM IRRADIATED By COUJmTET B AM3OF ?5Z0> HBPTROT3

F.A.Kl-B&kkoush, T.S.Akkl and R.H.MagahldDivision of Vadioal ApplloBtlons, Radiation andRadiolaotopaa Appllaatlon Saotor, and RadiationShielding, Ptajraloa and Hatarlala Solanoa Saotor,Tajura Huolaar Raaaaroh Cantra, Tripol i , Libya

Abatraot

UacMurementa hart baen oarrlad out to atudy tha atta&uatlon and distributionof alow naufcron fliuras at rarloua positions In tla*ua Ilka phantoa lrxadlatad byaolllfflatad b«a« of 2^Ct neutronm. Watar waa ohoaan aa a alnulatad ••tarlal toaoft tlsaua b«oauaa lta nuclear oonpoaltlon and affaotira atoaio nunbar naarlyoorraaponda to tha oonpoaitlon of aoft tlacua. Th» phantom undar invaatlgatlon «•••sda from polyathylana tank flllad with Mttar. Colliaatad dlraot and boson eaxbl-da filtered neutron baajw ware uaad. Tha neutron flux w*» aaaaurad using 'in(n, /")116In aotlration deteotora.

Tha neaaarad data ir* presented in tha fox* of attenuation ourrea along thabeam axis aud In planea rartioal to tha bean direction. These attenuation ourreaware uaad to oonatruot groups of lsofluz ourrea in plan* containing tha aria oftha lnoldeot beaa. In addition, tha resulta obtained for diao oolllaated are oon-r«rted to thosa whloh oan be obtained when the phantom la irradiated by infiniteplan* aonodlraotlonal souroa. Tha oonrarsion waa awda by Integrating tha Measure*flux distribution along the rertloal directions, Th* obtained reaulta oan be usaito eraluata th* slow neutron depth distribution at Tarious locations within anioutside tha beaa rlelnlty, Tha results also glr* tha dapendanoa of tha alda saat-tared neutrons on baaa dlaaatar and tlssua depth.

Tha use of fas t neutrons for Irradiation of the hwan body beooaes inoraaslnglyimportant In diagnosis ana oanoer therapy ( 1 ' 2 \ Th* potantloaal adrantag* of f a s tneutrons for th* treatment of oanoar i s th* high mdloblo logl**! *ff*otlT*a**s

- 99 -

(RBE) and the low oxjygen enhan;...*.' .i, rat io (OER) coraperod with gamma-raya. Thereduoed OER depsnda on the present a of hypoxlo oe l la In a tunor because the blood•upplj In the turaor la dlaorganlsed. The hypoxlo oal la ara much nor* reaietant tolow l inear anergy transfer radiation than wall oxygonetad oa l la , i . « . oalla Innormal tlasuaa. Thla la * dleadvantige In tba traatmant of oanoar with X or gamma-

raya(3.4)

In radiotherapy by nautrone, a ainr.ll part of tba body la aipoaad to a eolllma-

ted neutron beam or nautrona fron an Implantad oallfornlum-252 aouroa . Califor-

nium aouroa aralta a mixture of gaoma and flaalon apaotrua nautrona. Thla mixed ra-

diation field of nautrona and gamma-raye calcaa dlffloult to daaorlba physloally

a phantom which la being irradiated by mixed radiation beama . Tha oaaa la

avan mora oomplloatad dua to tha aeoondary gamma-rays whloh ara mainly a raeult

of tha radlatlra capture of thermal nautrona by the tlaaua nuolal. Therefore, it

beoomea of lntaraat to measure tha apatlal doaa diatrlbutlon dua to alow nautrona

In a tlaaua Ilka phantom In tha field of radiation therapy, further, for oorreot

application of oollimatod beama of * Of. radiation In teletherapy. It la not euf-

flolent to define tha ralua of tha del Ire red doaa to the malignant tumor*, tit

It la eaaentlal to know the abaorbed doaa along the aide dlreotlona outalda tba

beam rlolnlty(10).

In thia work experimental etudlea hare bean oarrlad out to determine tha apa-

tlal dletrlbutlona of alow neutron fluxaa In a water phantoa expoeed to oiflLllaa-

ted beaaa of < Cf nautrona. llaaaureaienta were performed ua)ng dlraot and B.C

filtered neutron beaaa of different diameters. The dependenoe of flux lntenalty

on the tiaaue depth and beam diameter waa lnreatigated.

aet UT>

The alow neutron fluxea dietrlbution In water phantom were •eaeured ualng the

experimental aet up ahown in Vlg. 1. Tha aet up Includes the irradiation facility

whloh aooomodetea the ' oalifomlvam neutron aouroa and a polyethylene tank fil-

Sohematlo diagram of tha experimental

layout.

1 - Irradiation Cell,

2 - Polyethylene tank,

3 - CJ-252 Source,

4 - Radiation Colllmator,

5 - Sample holder,

6 - Sample guide,

- Borlo aold,

- Lead enleld,

- Paraffin was

led with water. The irradiation facil ity ia oompoaed of ateel tank with outer dl-menalon of 100x100x125 oi. The tank ia f i l led with paraffin wax and aurroundedwith lead layer to raduoe the baokground to a level leee than 0.1 mreavh! The252Of neutron n i m la plaee« la tke eentral tuae. TUa aouree ylelto 7.B i l O 7

n<aeo"*at the time of meaaurementa. The irradiation cel l haa a herlaontal ohannelwhioh la designed to Mooaaodate beam oolllmatore of rarylng diametera up to 10em. The aouroe ean be mered to any position inside the asuroe tube and eutaldethe irradiation oell by a manual rempte meohanlaai.

- 100 -

The tissue olcfclated phantcn «ia* acde froa a polyethylene tank <5Oi5Ox5O CIouter dineosion) filled with ordinary water. Water was onoeen as e tissue liktcediua because Ita nuclear coapositlon and effeotlve atomic cumber 1B nearly coi-respond closely to the composition of soft tissue. Ix. addition, water ess be oon—eldered as doslnetrloally equivalent to »oft tlsaue, elcoe tbe absorbed 4ose forthe noae radiation field la approximately tbe aaae. The data reported bj Ixirld-•ea and Jensen Indicate that at large aouro* - target distance (>50o») th»

diffeience between the target doee rote for water and total soft tissue as bodyliquid 1B 175 for 137Ce' and XI* for 60C«:. However, ai email distance « 2 Q «•)the dlfferonoe can ba negleoted.

The alow neutron flux was measured using thin folia of lndlun detector*. Thisdeteotor was ohoeen beoause It la oonvecleat to obtain Indium In tbe form of pur*oetal. In addition, In(n, ») In reaotlon oroaa eeotlon bma a r»a»on«bla T»-lua to thermal and eplthermal neutrona, 15 and 2640 beme reanectlTelj. Indluafolia of 26am dU«at«r an< 0 . 1 M thiofc were u«e4.The fella van fli»* oo «fa«Uluaraple holdere made fro* yolyathjlana ahecta. Bj meane of th«ae «a«pl* holdaraand the two holder guldea fljed in the tank. It wma poaaible to ii<-iwur« the neut-ron fluxea at varloua poaitlone la plane* noraal and parallel to the beaa axl«.

Tbe gamma pbotona emitted from the activated Indlua folia ware counted bj ateanaof a eolntillation deteotor with HE- 13 liquid organic acintlllator. Sach aaapla•ss counted three tlaae and the avor&ged aeaaured aotlvitj waa uned to calculatethe activity produced for Irradiation tine of total saturation.

Keaoureraenta have been carirled-out using colllnated beaos of 3, 5 and 10 cadiameters. Eaoh aet of meaauremeDt wae performed with a direct beam, then repea-ted with a boson carbide filtered bean. The neutron flux was aeaaured at diffe-rent water depths along the baaai azla and in planes parallel (Z-dlrectlon} andvertical to the beam axis (R-direetlon). Measurements ware repeated at least threetimes for each case tc reduoe the experimental and statlaticsl e;rrora. The expe-rimental and statistical errors were calculated and it waa found that the aeasti-red relative neutron fluxee hare errors ot about -551 at depths where the flux In-tensity is relatively high. However, at depths of low flux intensity tbe errorwas within -12$.

3« Results and dlsouselons

The spatial distribution of slow neutrons resulting froa> oolll«*ied beaas of' Cf. neutrona having different diameters passad in water phantom was depictedfrom the oaloulated activities of indlun foils irradiated for the tiae of a to-tal saturation. The relative flux intensities are plotted versus water depth inplanes vertical to the be«ra axis and ara displayed in Fig. 2. This figure Is de-vldsd in parts A, B and C whloh corresponds to flux attenuation curves for beaasof 3, 5 and 10 cm diameters respectively. This figure shows the spatial distribu-tion of slow neutrons measured in water phantoa both with direct and boron car-bide filtered beams.

The attenuation curves presented in this figure show a oertaln build-up of slowneutrons at narrow water depths. Starting with a depth of about 6 ca, the attenu-ation curves show that, the flux Intensity deoreases exponentially with lnoreaslncthe depth. It can ba also notloed that the depression la flux intensity with wa-ter depth deoreaaee with inoreasing the depth of the plane for whloh the attenu-ation ourve le plotted. These behaviours are nearly the saa* for tooth direct «ndB4C mt«r»d beams. The attenuation ourvsa plotted for 11 0 filter** neutron fceeawshow that, absorption of neutrona with energies below 10 KeV by boron aarblee f i l -ter reduoes the amount of slow neutrons In tissue aaterlale. The boron oarbidefi l ter has the effeot of reducing slow neutron Intensity by a factor of 2 at wa-

- 101 -

g .0

1 *> •» 12 IS I H 0 » 6 9 12 IS IM O < 6 0 U IS

Tig. 2Attenuation of total »low neutron fluxea In water phantoa Irradiated by oolllaa-t«d beaa* of r" Ofi neutrons

Dlreot baaa( — —Boron oarbld* filtered beaa.

tar depths below 6 oa. Thle reduotlon deoreaaaa with Increasing the water depthaalong the rertloal and beaa dlraotion.

figure 3 shows the laoflux nape plotted for elow neutrone In water phaatoa whenthe water phantoa la irradiated by direct colllaated beaca of 2'2Cf neutrone ba-ring 3, 5 and 10 oa In dlaaeter. laoflux aapa for neutron beaaa filtered wltn B.Cere aleo displayed In this figure. These lsoflux aaps refer to a eeotlon contain-ing the stria of the lnoldent beaa for a fixed oolllaator length. These leofluxeurres are napped for fluxes of equal Intensity. It oan be observed that, selectionof an appropriate lsodose or laoflux ohart la difficult einoe the aeasurad fluxdistribution in the phaatoa depends on the beaa dlaaeter end water depth. In addi-tion, the lsoflux ourres show that, the pile up of slow neutrons at various looa-tlons within the bean Ylolnlty and along the side direotiona depends on the ener-gy range of the incident neutrons. Tbeee laoflux ourree aleo abow tb*t, the Inten-sity of neutron dose delivered to a voluae eleaent at oertaln depth along the baaaaxis largely depends on the bean dleaetar.

The data obtained for oolllaated beans of different dlaaetere were converted tothat whloh oaa be obtained In oase of infinite plane aonodireotlonal source by in-tegrating the flux distribution in planes nomel to the bean axle (R-dlreotion)for fixed water depth (Z-dlreotion). Praotioal evaluation of the flux 4letrlbutlonsfor Infinite plane aonodireotlonal source at different Z values were perforaed bydettrains tbe are* under the ourves* whloh relates ?(Z,*.)x*.-rems K for JUO tefor different values of Z t l 2 j.

She relation* between flux calculated for infinite plane nonodlreetlonal w o >ee versus water thickness for both direst and boron oarbid* filtered neutron eeaneart given la Tie* •• Slaiiar relation* are alee displayed for oolllaated bean* ofdifferent disaster*. Theae attenuation ourvee ehow a oertaln build-up of alow neut-rons at narrow water depths. It oan be also notloed that, startla* with a depth

- 102 -

Iiofl-.ii cfc*rt» of

total alow

la nttr

lrr»41«;t»a b? eol-

ll&fttad bsaaa of252Cf. n«atrona.

OlrMt

boroa *«r-

6 en attcnuatlm alcpaa aspoaaatlally with aaaataot attAnuatlaB laastk ovarall tha ran«aa of HMun< daptha. Tba alopa of ttaa *ttaau»tl«M anrraa wltkla tklaracloa » M dtrlraa by tba la*a* a^uaraa f i t . Tba anra««ca valuta off raluwtloa la«ctha X tor total ale* nwutrooa (both Alraot and l C f u t i n t baaaa off ^'off. aa«t>M M • * • P*aa*« In «a,tar phantom) »r« darlTad tor 41aa eolllMtad and Lnflalt*na aoDodlraotloaal aouvoaa. In e m off dlao oolllMtad eaaM, tha Mn& Taluaaof i i n

A - 6.18*0.31 <>• for dlraot baaawaad X - 6.82lo.33 aa for B4C fflltarad baaaw

Tb* rmltM off oaloulstad ffma tba attrauatlon ralatlona plottad for taflni-t# plana aioDodlMotloDal aouxoa ara

> • 7.72-0.35 m for dlraat baaaMand A • 8.02to.35 <m for »40 f l l tand baaaai.

Tha raluaa of A jl-ran afcora ahcw that tba ralamtloa lanctb of ala«raaaltlac from tba alonrlnf dow of aautrona with «narcl«« mb9v «ba«t 10 IaTflltarad baaaw) la (raatar than tha ralaxatloa l a n e * a«loula.tad for dewproduaad «ban • dira«t baaaw ai* yacaad la wtar fhaatoa. Tkla oam ko aittrlaatadto tha faot thftt, aaatrou aff aaar«la« balav 10 KaT (orljl»ally yrwaat wlthla *k»looldaat aMai) taad to laara«M tha claw maatroa f l » mtunmi at «MLU wtar

- 10J -

>

1

at

to'

1 I i rig. 4ltt»-B'jJitloB of total alowilia*a in watar phcstcn irra4la-t»fl bj 41»o oollLastte {£.) «esAlaflalta pl«n.» (In.) B)t?cofSlr*a—tloo M w of 2*2Cf trot roe*.

Blract baa*,beroc eajtdd* filtar*d

tba. Tbtrafora, tba attaauatloa ourraa obtalaad for dlraet baaaa will har*clopa tbaa tha attanuatlon eurraa for B.C flltarad baaaa, bcsoa, tba valua of Xfor dlxvot baaa, wil l ba laaa tbaa tba oorraapoc&lac ralua for B C flltarad *—*--It can ba alao obaarrad tb&t tba Taluaa of A obtalaad for Lnflalta plaaa aoeoAl-raotloual aourca la hlghar tbaa tba valuas flran for Also oolllaatad baama. Thlmla dua to tba faot that, la oaaa of laflnlta plaaa aoaodlraotlonal. aourea, tbaaf faot of alda aoattaraA aautroa baa a proaouaaad affaat on tba nautron fliai aa-aaurad alone tba baas axis, atpaolally at Oaap paaatratloa. Tharafora, tba affaatof alda aoottarad nrutrona will ba aora notloabl* la oaaa of laflalta plaaa awao-dlraotloaal aouroa tbaa la oaaa of dl*a aoaodlraotloaal aouroa. Tbla will la tura4*or«a«* th* rata ot rappraaloa la Slta lntmatltj aloof tba baaa arl* is oaaw oflnflalta plaaa aouroa.

Conclusion

Tba raaulta of tbla laraatlfBtlon hara daaonvtratad that:1. Attanuatlon of alow aautrona* ravultlng froa oolllaatad baaaa of 2 '2Cf aaut-

roaa ara paaaad throuflb watar pbaatoa baa a oartala build-up behaviour «t narrowwatar daptba. But for watar daptba tftartlac fraa about 6 «a, tba attaauatloa emr-rtm abow that tha flux latanalty daoraaaaa axpoaaatlally with Inaraaalag tba daptb.Za addition, tba flux attapoatloa ourraa cl-fa an Ixdlaatloa that, tba latcaalty ofalow aautroo flaxaa aaaaarad at dlffaraat daptba alonf tba baaa azla and la plaa«aparallal aad rartloal to tba fcaaa dlraatloa, lmrgtily dapanda on tba baaa Alcaatar,watar daytb aad aaaxu ranja of tba laoldaat aautroaa.

2, absorption of aaatrona with anarglaa aalow about 10 laT by boroa aarwlaa f l l -tar raataoaa tba aaoant af alaw aautroaa by a faotor of 2 at watar daptha balaw iam. Thl* raanatlaa *»mtmmm»m wltb lasraaaiaff tba watar da*tb mlmas tba baaa am*rartlaal dlraatloaa. Tharafora, tba praraatlaa af alow aautroaa wblab ara aaaactba laaldaat aaatvaa aaaa tasda «• Mm— a laraa aappraoalaa la tba lataawlty af

- ict -

««-itlRg frca tfca ratlatlva cijiurt cf

asAll ttp'.ZM.}. Zb.9 ecs j ia i i t j cf :fc» r»41«:l<ra fiaid 1c ptaatsw *tioa 1*

by es.i:iaBt»d teaaj = f J^2Cf eaatwra oak** filffle-j.lt to fitaes-lbe It yi?£er«5cr», i t fcascsaa tf :.;.:«?reat Is tfca flalfl of r*fll*?ics liter*.?/ to Ao «ijj»rlT.*:.I±1 studita to t»«««« tfct *j-»»i^2 ACS« filatrltaile-s* i-« toXM-Ta.ja Ls !!«•-;• air.ul«t*d. ûu:tcE. Ihla 1* a ;rar«!]'ul»it* for c

'.be cairg«t Tî'jst la i»ti

ia *cul£ ilk* tc K;tao*lt«9£« ['r.£./£»iajj, "«»S oi' fjieimtlcjc tatAptfllCMttes Ctotor *;:« SJr.lt.Kha.lsf, H«ad of rnjaie* *ti ktatarlafor ti.tlr lnitra«t axd «sccur»<*«rrjSa. It Ja «i»o • plautura to tbwk Tbao*l a:**.' c* tit* •orkalsep :"'•'• r th«lr t*cihj-.l«*l (t«tat«re> *r,<J for

1. i:.~oiif, 1.Hollo**}. tm6 A . n i l o t , ?h>a-lC»fi.31ol. j ^ , 37? (1974).i . H.Ios and i.^.Crca*. "Sp*ctra ati lictiv.tlrj R«lat«£ lo EautrcD Irrafllatloo

of the Kittraa Botfy". rn?*.He£.31ol.VO3. £0, 6, 9O6-917 119755.y. £. ".Stall. 'R*eiotol*logj tor t&a $*eieiegXmt-1 Karpar aosJ Sc»

Had.. U973I.4. •.!«««•£,, *?«jt J.fjtrojja lo Sn^lothcrapj* la K.E.KaJjnaa, M.

taâ lr. ---.:• 7 «uv? n.a£iott9er*raulloa, CUniceJ. Cnctlogy. Churchill 1.3»J.Ti*«tona,EdlBtur«h, 1 i*.17 -).

^. :.r..3avla7. Curr. ."oplea Ea4l«t.Saa. UJatb. ), 4 , 2<S (19703.6. L.S.HaU. H.mogal. "Ttea Fotantlal of 252Cf l£ R**lotbai«py PraoMnJcaJ

y»ajsur».-«r.ta Is fhjalca and :«(!lcth«r»p7". Bi-.J.Radlol. j£ , 777 Oct. (19753.7. T.V«ra7«r-», "Hapld Jlaaranoa of Afivaaoad Falvle rarolnoaia* by lo* ivv ra,ta

473 »o». (19795.dlobaology ax.C Hadlcal Appllcalli-aa*', I'roeaa*-

inga of tha Sr-j(i»*la -'jFapcaluB of ttaa LntexbatloDal Sycpoaliai oa Callfornlua; tJtl-

•?. r;.S.Itlreaa, H.I..l«*ranc«t R.Vartlo, "C*llfo7nlia»-2^2 Doslaatz; In Phantoa»of »arJou» Ilranalon*" Ha4lol. ^22 ^ 9 Oao. ilêc).

10. U.cldantmrx, J.Boos, ?roe.Tblrd Sj«p. on 1LICTO6OB\»%XTJ, Straa« 15-22 >0et..Euntua Saport, iTJH 48I0.fl.f.a.P. 511 (1971).

11. B.IaurOlfan, P.R.Janaas, 'Esparlaantal Tarlfloatloc of Intair- DoalaatryCaloulatloaa Conatruotlon of a Katarofaooua Fteatoa t>a«ad 00 anas f jafia'. }rtIni.^/ap.ftad.Pbâ., r«rr*ra, Italy, 30 Say.-4 Oat. (1905).

1?. n.a.Magabld, A.S.lUkaxoua, M.*.E1-Ko1alj, "Attanuatloe of Ra«ator3>«utrona In a bulk 3hlal4 of Ordinary Cosorata", Axm.Kuol.&itrgr, fi, 119B1).

- 105 -

: : : . i s v : p « • » • A i s s s u i nA 3 3 V 1 A S C S I X U D I C ? S I B I F !

i n . P a f s • B c ; c r i n c i i m A t m s f t t i i 1 1E 7 A L I ? T T i i c i 9 i t u r : :

AFFflOAgg

tc A IBID HAEIATICE T

Rua* laiatta3<parcaist of Kadlatles3oi 6 02 04. 3-104 01 Staofcbela, 3»a«*B

?ba ScasAlrarlae or Xor'tle ecantriaa ara kt. *asy ,-«aaj>wta vary alatllwr.ag«a, polltloal atrusturaa and aeslal oara-takLag *j»fm ara •laoal aq-nl. OB tb»-•a ground* oooparatlon baa baan aa<abllahud Is ajany f la l ia . Aa attowa i stba oountrlaa bava a low aarulatloa aaaalty «£vaata dlataooaa satwaan boapltala.

Taila 1

CountryDenmark

laland

Svadas

_Inhabltanf5,1 x 1015

4.9 •3,22 "

8.3 -

Madleal phjaioa In thia **»%, •t«rt«d bj tha Tolont»r7 wort by Slerart In 19219.In tha 1930a an£ tha 1940a i«dl«tloo phyaloa axpandad In Svadan mat to a ! •«• •»-taat alao on tha othar oountrlaa. In tha 1550a hcapltal phjaloa Isoraaaad rapidlyIn a l l tha eountriae. «itB * aaall nuabar of hospital physlolata In aaeb count17,hovarar, i t took • lone tlaa until national orcaalsAtloea wn aat ip, tha flratIn Svadan In 1957. A lordlo ooUabozmtlao « M atartad in 1962 «tian th» Kordio Aaao-olatlon for Cllnloal Thyaloa CHACP) « u oioatcd. Ona raaaon for thla «»a tba *l«bto aaaoolata with tha Intaznatlonal OrcanlMtlon of Madloal Phyaloa (I0W).

•lthln thia fraaawork awrtral ooamlttaaa *ai« aat up In tba eoaaian lstaraata ofphjalciate In tha oountrlaa. Aaonc*t tfaaaa waa • ccnalttaa on ooaiputar applicationfor doaa planning aatabllahad in 1965.

On tba bwia of tba work oarrlad out by thaaa ooaaUttaaa It waa poaaibla to gataupport fro* aosa ooaaon Rordlo (otranuMntal organlcatlona Is ordar to improve co-oparativa afforta batw«an tba oountrlaa. Tbla oontinuad through tba yaara aad tba•oat important work baa baan oarrlad on* la tba ctandardlMtloo of doalvatry (1 ,2) .

Tba CART program oan ba aaaa aa a continuation of tbaaa afforta. A group of a«i«a-tlata froai lordlo boapitala aad raaaarob and daralopaant oactraa atartad with tbaaupport of lOROrossx, to work on "Oaar Haqulraaianta on CT-baaad Ccaputad Doaw Plan-ning Syat«aa In Sadlatloa Tbarap7" O) whlon waa publlabad In 1983.

In 1983 lordl* lndoatrlaa aaoaytad tto aaallanga and foraad togatbar with tba aW-ra aantloaad group ac lnduatrlal pra-projaat alaat at apaolfylag tba prodaata to Mattba "Oaar Kaqolraarata-. Tala »ra-projaa* waa mlmrn apanaorad by a Bordla lnaaatrlalfond. Tbay publlabad a raport "Praaantatloa of aa lntagratad lnfomatlaa ayataa 1Mraaiatbarapy . Rapart of tba ara-«ta«y pbaaa 1984-03-15". Tba CAST »rocraai la aa* lalta third abaaa. Tola abaaa alaa a* raaaarab aaraleyaNMt m* taatiac • ' * »rataty»a

- 106 -

for the next generation of products and systems for radiotnerapy.

Nc'RijFCKSK, the Nordlo cooperative organization for applied research, has taken

an uotive part In CART since the first activities in 19Q0, and supported CART with

tome planning oosts, praotioal program planning and financial strategies. The CAST

program board Is appointed by the HORDFORSK board, thereby forming a legal bodj

for the CART program.

The CAKT program

Figure 1 summarizes the aotlvltiea of CART and a time schedule for the progru.

CART has now passed the prestudy and Is at present In between the prototype and

the produot developments. The figure also lndloates the various oompetenoe groups

whloh were established and the projects «hloh are now under development In varlouc

taobnloal groups.

A IMordic challenge in medical computing

J [

Comp*tenc0 groups

""*^<'J [_!_'•• tm»-»i Co-lip/ [ I g

1983

Pig. l

—^ 1 .!

CARI \ /TAMPERE \ / UPPSALA \ f HALMO \ /RE»KJAVIK\ / OSLO

STANDARD/ \ (FINLAND)/ \ (SWEDEN) / \ (SWEDEN) / \ (ISLAND)/ \(NORWAri

INDUSTRIAL OEMONSTRATORS

Pig. 2

- 1 0 7 -

Flgur* 2 indioatea the organizational atruotura of the CART program. Under MORD-

řORSX the program board has been eatabliahed and ia reaponslble for the various

elx projects. The first of theae i# the "CART STANDARD" projeot headed by doctor

Torgll MBUer in Sweden. The main aim oř this pyojeot ia an lntertLatlonal ooope-

ration on nomenclature and oommunioation format to be uaad at all the other pro-

jeota.

Five different projaota have <o far baen atartad and ara at praaant In prograaa.

Aa ahown on tha figura there ia ona projaot in Tampara in Finland with the main

aim of aataMiahlng 3-DBtENSIONAL DOSE COMFUTATIOB MODEL, including treatment oon-

trol and network. In Uppaala in Swadan a group ia working on IMAGE handling and

tha MAN-MACHINE COMMUNICATION M wall *a tha network projaot. In M*lmC, in tha

aouth of Swadan, another group la working on TREATMENT CONTROL, PATIENT FIXATION

ETC. In Reykjavik on Iceland , GardM Myrdal and hla colleagues are working on an

ONCOLOGICAL DATABASE and tha network oonneotiona. The laat project whioh haa been

atarted recently ia aatabliahed in Oalo in Norway and ita work ooyera CT-IMAGING

and SIMULATOR oonneotion to the network. We will later take a nora oloaa look to

some of theae reaearoh projects.

FiRure 3 la a aummtry of the data oommunioation flow aa it la expeotad to be

<*t up withtn th# proj#ot#. It icdloataa th* information flow from tee varlou*

equipments nnd tha dlagnoatio prooedurea, how they are coming into the network

and oan be utilized for the varloua prooedurea of radiotherapy and finally be ato-

red in the olinioal ragiater. It is obvioua from thia slide that we need a proper

standard for the network and that eaoh station in the network can oommunioata with

stations in an eaay way.

DATA COMMUN!CAT)ON FLOW

?ig. 3

The main theme for the CART STANDARD projeot ia to work out information inter-

faces and atortg* for*a,tea whioh will make poaaible a. funotlonally lnforatation flow

cithin tha r*ďiothar*py ollnio. Tha CART STANDARD projaot la davided Into three

areas:

1. Medioatl data dealing with baaio patient data, laboratory results, t ataent

documentation data and treatment reference data (in part). The main tasks :.ra:

- 106 -

Definition of medioal parameters relevant to onoology

Suggestions for validity controls

Curv«y of legal and etbloal aspeota

2. Image data dealing with problem* Inherent to elagnostio and therapeutic

iranges and treatment referenoe data (in part). The main taeke are:

Leflnltion of coordinate systems

Logloal format of linages

PACS (Picture Arohiving and Communication System)

Image representation

Image presentation and man-machine Interaction*

3. Eoalmetr? data dealing with radiation referenoe data, treatment, referenoe

data (in part) and treatment documentation data (In part). The main tasks are:

Absolute doalraetry

Beam data acquisition

Ream modifying parameters

Kilt beam detector system

In vivo dose measurementa

Set up verification

Conformation radiotherapy

CART Demonstrator Tampere, Finland haa a main theme to develop 3-dlnenslonal

dose calculation algorithms and the present projects are

31> dose computational models

Treatment oontrols

Imag< processing station

Expert system

Network

CART Demonstrator MalmO, Sweden haa the mala tteme "treatment control":

Position of radiation fields in the patient

Control of treatment parameters

Doslmetry control

CART Demonstrator Uppsala, Sweden is oonoentratlng on image handling for radio-

therapy treatment modelling,but oovers also several other areas<

3D image handling/analysis

3D planning for proton therapy

TUC-Treatraent Uodelllng Station

Application of llKI-technique

3D computational models

Icage data base system

Han-machlne Interface (HCI)

Network

Automatic patient contour device

The CART Demonstrator Reykjavik, Iceland is concentrating on the onoological

data bane. This work is baaed on the Information as recommended by WHO, 1976.

While most of the demonstrators work according to more or less established li-

nes, the project in Oslo Is concerned with a redesign of a simulator with the aim

of introducing a radiotherapy oriented CT-teohnology. This la baaed on a newly de-

signed deteotor array whioh will feed all the necessary pioture transmission infor-

mation Into a microcomputer which can produoe a CT-soannlng pioture.

A large number of Scandinavian Industries are involved In the CART program. They

have supplied computer* and equipment for each of the demonstrators and they con-

tinuously support th» demonstrators during the development. The industrial ooope-

- 109 -

ration requires an agreement which is signed with NORDFORSK. Thie agreement la a

statement about the support given by the particular industry, the responsibility

of the project leader and a statement regarding the future use of the development*

whioh are being made within the CART program. The scientifically oriented project*

are usually supported through national funds and granted on the basis of eoientl-

fic evaluation as usual for independent research projects. Support haa for instan-

ce bee i given in Sweden to the development of calculation algorithms for pencil

electron beams for dose planning purposes as well as a photon doss calculation

program based on the fundamental Jadiation interaction prooesses. Such energy de-

position programs lead to what is called « Jrernal type of absorbed dose distribu-

tion calculation. The full implementation of such baslo teohniques will make It

possible to calculate with a higher precision the 3-dlinenslonal dose distribution

In complicated structures. One of the main oonoerns of the project at the moment

Is, ot course to find a proper method for the 3-dimensional demonstration of the

doao distribution. In this area several different approaohes are being tested.

Conclusion

The cooperation within the CAM program oovers the utilization of oomputers In

all steps of radiotherapy; from the administration of the v-atient until follow-

up and epldemiological studies. The total projeot Is too costly for any single

institution and therefore a nordlo cooperation has been established. It has Its

main financial support from a considerable number of industries and their contri-

bution and responsibilities are oorered by an agreement with NORDFORSK. The pro-

jeot is now in the product stage and within one or two years time some ot the in-

dustries will probably ba able to offer, on a oommerolal basis, the result from

these combined Nordic efforts.

Referenoas

1. KACP: Procedures in radiation therapy doelmetry with 5 to 50 MeV electrons

and roantgen and gamma rays with maximum photon energies between 1 MeV and 50 l!eV.

ACTA Radiologioa Therapy, Vol 11 (1972) 603.

2. NACP: Procedures in external radiation therapy dosimetry with electron and

photon beams with maximum energies between 1 and 50 MeV. ACTA Radlolcgioa Onoolo-

gy, vol 19 (1980) 55.

3. Dahlin H., Lamm I.L., I^ndberg ?., Inverness S. and Ulsrf H.: User requirements

on CT-baatd computed dose planning systems in radiation therapy. ACTA Radiologioa

Onoology Vol 22 (1983) 395.

CONSERVATIVE TREATMENT

0? BKEA3T CARCJBlHA

fflTH INTERSTITIAL BOOST DOSB

E.LBffler,

Strahlenabtellung der UniverslteVts-PrauenJclinllc VOrsburg, West Germany

Introduction

With the lnoreased awareness of radiation risk, the use of interstitial therapy

beoame sore and more unpopular la Germany, tow, with speolal remote oontrolled af-

- 110 -

terloadlng machines the interstitial brachytherapy will have a renaissance (4,7,

8,9,14,15).

In comparison with the teletherapy there are two great advantages of the con-

tact therapy: Having the same reference volume the integral dose in the target is

higher and the treatment volume even lower. In the case of breast conserving the-

rapy this allows a high dose in the tumor bed by sparing the skin and lung.

Treatment Policy

Therefore the management of early breast cancer (Stage I and II) at the UFK

V/ttrzburg consists of lumpectomy and axilla dissection, followed by a boost dose

of about 20Gy into the tumor bed, given by an *92i implant. In an external beam

therapy the whole breast is additionally irradiated with 45 Gy (5 fractions per

week each 2 Qy) (14). In the case of positive nodes a chemotherapy is following

after completion of the radiotherapy.

Implant Technique

According to the Paris system (2,11-13) we Implant parallel 1.5 mm thick ri-

gid guide needles that are held in place by perspex templates. The templates are

perforated in a way to keep the needles in a triangle geometry to get a homoge-

neous dose and are placed symmetrically at each end of the implantation. For adapt-

ation to the target volume we use a separation of the sources between 14 to 20

mm. In most cases 2 planes of needles are implanted. Before the final adjustment

of the relative position of each needle, stainless steel clips are clamped over

the needles and fix«d with the immobilisation buttons to provide a constant pro-

ximal distance to the skin. The distal ends of the guide needles are trimmed with

cutting pliers, a few millimeters beyond the implant. For calculating the needed

active length of the sources the distance from the end of the needles to the skin

is measured.

Treatment Planning

After implantation a set of isocentrio stereo radiographs of the implant is

made (6). These radiographs are used to reconstruct the positions of the needles

and skin points (Fig. 1 ) . The contour of the breast is reconstructed using lead

Pig. 1

•> •'? j/f ^^^^*^^^^^9^^' Isocentric stereo radiographs

for reconstruction of a two-pla-

ne breast implant with 9 needles.

The stainless steel clips are

clamped over the entry and exit

of each needle. The lead markers

show the breast contour near the

central plane.

markers. The exact length of each Iridium wire is calculated. A few millimeters

of non-irradiated healthy tissue should be left at the entry and exit of each need-

le to spare these points.

The computerized dosimetry (6) is based on these stereo reconstructions, con-

sidering the 0.1 mm Iridium core and the C.I mm capsule of platin like an unencap-

- Ill -

eulated line eouroe. Aooordlng to the Paris system of doairaetrj (2) the referen-

o* volume la assessed ualng tha mean doae rates Ln poluta midway between the tri-

angular lnaartlon of tha wlraa. Thoee points lla ln a plans that muat be normal

to tha parallel wlraa and haa to ba positioned ln thair cantor (Pig. 2a). The rv-

PLA»€I 2 M i l

S0LRCF3

/

(- -\

\

/

\

.. J , . .

01

Does distribution of ir. 192-Ir Implant

ln the tumor bad of n breast t-usor af-

ter debulkln^ of the tuaor (the refe-

rence volume is shaded, also the region

with a dose twice a« much as 'ha refe-

rence dose):

a) Central piano according to the Pa-

ris doslmetry system (Basic dona

rate points +).

b) Pose plane midway between the need-

la planes with a view of the acti-

ve aouroes and tha skin points.

o) Lateral view for oheoking the pa-

rallelism pf th« needles.

ferenoe dose rate is oaloulatad as 85% of the mean basio dose rate. The treatment

time calculation la baaed on thla dose rats. The dose distribution midway between

the two planes of needles is used for the determination of the reference v >lurae

(Fig. 2b). The view of the aotive wire relative to the specified skin points

(Pig. 2o) allows oontrol of the position of the guide needles. This is Important

if the aouroes are reused. All source assemblies should be prepared with the sa-

me inaotive length relatively to the positioning pellet. The distance between the

conneoted side of the guide needle and the skin has to be the same for all im-

plants. For this the needles are marked. In order to reduce the in'ier of sour-

oes we prepare oertaln aotive length* from 20 to 95 mm in steps of V> ton, accor-

ding to tha frequenoy of use.

Souroa Preparation Initlfl Doalmetrr

Tha souroaa are assembled from 50 om Iridlum wires with a nominal specific ac-

tivity of - 10 UBq. mm. The wire la out ln a speoial preparation station (Fig. 3)

- for exposure free handling - and sealed in a thin plastio tube union ie crla-

ped on the Inaotive guide part of the source. For automatically loading into the

afterloading unit there la also a coupling crimped on the inactive part (Fig. 4),

To determine the strength of the source as basio data in the oomputer doalMt-

112 -

r

Fig. 3

Exposure free handling preparation

station

Fig. 4

Schematic diagrams .if the source assemb-

ly, marked guide needle and the trans-

port tube. The adapter part and the po-

sitioning control pellet Is crisped In-

to the fibre guide wire. Also the nylon

tube with the Inactive and active sour-

ce part. The Inactive source length is

adapted on the marker position of the

needle.

ry all sources are measured in a well type ionisation chaaber (Pig. 5). The cham-

ber current is calibrated against a reference 19 £j wire in kerma rate. The aya-

I"

chamberw«ll»—(AU

cotlaction•lactroda-

Ml)

\ Fig. 6

Linear activity meter: Electrometer with cy-

lindrical ionisation chamber.Fig. 5

Schematic diagram of the well

type ionisation chamber for the

initial doslmetry of the 39 2I

source assemblies.

tematio error of this calibration is 3% (7). In an Initial check the linear acti-

vity is also measured using a ring shaped icnisation chamber (Fig. 6) behind a

1 cm colllmator opening. This allows to check the linear activity distribution

of the whole Iridlum wire.The homogeneity of the activity was better than 1OJC.

The results of the well type chamber measurements are listed in Tab.l. The devia-

tion from the manufacturer's (Amersham, UK) certificate of calibration is smaller

- 113 -

Batch

P 45930U 15505Y 35703C 25761C 35651

coils

13332

sources

226331614

dK/dl

uGyh-V™

1.201.211.251.321.22

6

r1 *

-3.9

3.60.60.2

-0.6

SD

%

0.24.73.70.81.2

Tab.l:

Measured deviation and standard deviation SD of the speclfio

referenoe air kerma rate dK/dl to the manufacturer's protocol

of calibration

;han 4%. The standard deviation of the source measurements prepared from the same

coil was better than 5%.

Remote Control Aft&rloadlne Technique

Instead of loading the needles manually a remote control afterloading device is

used (7,9,10,14). For this afterloader (Mlcro-Selectron, Mucletron, NL) (Pig. 7)

a set of max. 45 prepared sources is loaded in a storage container. The UicroSe-

lectron oan pick up 15 sources and transfer them remote controlled into the inter-

mediate safe for the patient's treatment. Before the treatment is started a film

of the loaded sources is made to confirm their length and position (Fig. 8). The

Pig. 7

The ttlcroSelectron afterloadingmachine with the main storage

safe.

afterloading device is connected to the pktlent by a quick-release coupling. A fib-

re drive mechanism provides a highly reliable source transfer into the implants

with a precise pneumatically controlled source positioning.

Dose Rate Correction

The Irldiua souro* aaewibllaa are reused within about 4 month*. The linear aotl-

- 114 -

Fig. B

Autoredlographlc check film of

the loaded sources for confir-

mation of source length end po-

sition.

vlty of a later application is considerably lower than the earlier onee. This to-

gether with the variation of the reference volume by adapting number of n«edles,

the length of the sources and the separation of the needles will bring a rang*

from 25 to lOOcGy.h in reference dose rate (Fig. 9). This high <3ooe rat» V v*rla-

Pig. 9

Variation in reference dose rate of 29

breast implants.

tion must be taken into account (3) and can be compensated in a biological treat-

ment planning, using the linear quadratic model:

-lnS = a-D + q(T)-0-D* (1)

On the basis of this formalism relating the cell survival S for induction of

cellular effects to the absorbed dose D, in which °& and /3 are constants, K«ll«-

rer and Rossi (5) Introduce a time effect correction factor q(T), where T Is the

treatment time. The sub-effective lesions increase with the square of the dos« and

remain available for interaction during a limited time after their production. In

assumption of an exponential repair function of the sub-effective desage

q(T> = OTT I1 ' JITT H-exp(-u-T)]] (2)

with a time constant /U, - 0.693/t, where t is the half-life of the sub-lethal da-

mage and ranges between 0.5 and 2.5 h«

Following Barendsen (1) the relative effectiveness per unit cos* is then:

RE = 1 + q(T)(§)-Da

and the extrapolated response dose:

ERD = D-T-RE(T)

(3)

(4)

For the range of the treatment tine from lOh < T *£ lOOh the corrected treatment

time is:ERD + 2-D (gj

1 T i^D (g)U a

(5)

- 1 1 5 -

Aooording to Bar*oda*n (1) and t^^ watlo of 5Gy ta ua*d for th* lat* <ff*et*

if t^< oonn*otlT* ti*<u* of th* br*a#t ia r*gard*d a* critical. With * nortaliaa-

tion of th* *xtrapolat*d raapona* doa* to 50oQy/h Í200y in 40 heura, ERD - 285y)

th* oorrtotlon faotor of traataamt tma or pr**orlb*4 doad varl*a in a don rat*

rang* of 25 to lCOoGy.h^bstwatn 1.2 to 0.8 (Fig. 10) if ,íí, 3 0.46h"^ Chalf-lifa

tim* t - 2h).

Th* r*aot* oontrol tfttrlotdlns *llNln*t*# th* r^di^tlon h*tM-d for th* ettff.

An *ypo*ur* fr** handling př*p*jring atatlom *JJ.&wa to Mnututur* th* aoure* #;#-

a**bllt* uaing ooila of Irldlsm wlraa. Th* ialtlal dowlm*try ahcwa * good *<gr*#-

K*ct -ith th* o*rtifio*t* of o*llbr*tloa glv#m by A**rwh*n. With th* r*mot* oon-

trol *ft*rlo*dlnt th* ao^^ro* *M**bll*a Mř* r*u#*d ov*r # l&n^*r p*ríod. Thta

bring* n*w **p*ota for tr**,tn*nt plamnia^! Hyatly *n ladivldu*l ph?aie*J plamnlag

bM*d on i<oo*ntrio at*r*o r*wo)Mtruotiona of th* i*pl*at Mtd furth*ron th* varia-

tion of th* doa* r*t* i< oorr#ot*4 u#iD^[ M *3tt*nd*d llB*ty qu*dy*tio fora*llan.

Than th* eorr*otlon faatoť r*ng*< b*tw**n 20%.

Lit*r*tur#

1. Bar*nd<*n, G.W.: Doa* frMtionatlon, <!o<* rata and lao-*ff*ot r*latlonahipa

for normal ttaaa* reapona*. Int.J.Radlat.Onool.jBlol.Phya. 6 (1982), 1961.

2. Dutreii, A., Q.H*rin*llo, A.Tamb*rai*: Doalmétri* an ourí.*th4rapi*. Naaaom,

Parla 1982.

3. Hall, B.J.! Radiation 4oa*-r*ta: a factor of iaportanoa In radloblology and

radiothorapy. Brit.J.Radiol. 45 (1972), 81.

4. Jacobs, H., P.Tauaoh, V.Sohlappl, A.SohatladaT, G.Monct*: Intwnatitlalla BT*-

ohyth*rapi* - !rat<# Zrfahrungan Hit 192 - Iridium in d*r Knřas*itth*rapi*. atraJtlan-

th*rapia 160 (19B4), 8.

5. K*ll*rar, A.M., H.H. Roaai: Th* thaory of dual radiation action. Curr. Top.

Radlat. Raa. Q a (1972), 85.

6. taaraa, R.v.d.t Traatat*nt Planning of Intaratltial Radlatharapy (MPS) with

th* 3*l*otron Traatn*nt Planning Syatam. In! Braohy^harapy 19B4, Prooaadinga 3r*

Intamational Salaotrcn Uaara Maatlag 1984, M . ! R.T.Mould, Pabl.Huolatroa Tra-

ding BV, Laarwnat 1985, p. 286.

7. Mffl*r, 3., O.Saaar, K.Rotta: Intaratitialla Low-Intanalty Aftarloadlng-

Th*rapi* Hit ^^Ir-DrJUttaa. Mád.Phyalk 1986. M.:L.v.mt<lng, DBMP, Mbaok 1966,

p. 433.

8. Mfflar, H., 0.3auart 3-D Hakonatmktion ven Btuat-Implantatan aur Applika-

tlonakoctrolla Mnd BaatzahlvngaplMtung Hittala taoa*ntrlaoh*r ataraoakopiaohar

RHntganaufnahnan (MR) untar BarHokalontlgwng ainar famgaatauartan intaratltial-

lan Na*hla6*a*thoda. Sttahlantharapla, In Praaa.

9. LHff!.ar, Z., K. Rottat M.a WHraburga* Mathoda ear famgaatauartan lntarati-

tiallan low-doaa-rata Braahytharapia bal dar bmatarhaltandan Bahamdlung daa Manaia-

karainoaa. Ie< VarhandlMngabatloht day Dautaehan Waaallaohaft fHr OyntUcologla and

Kaburtahllfa. 46. Tagung, Htaaaldorf, Sapt. 19^6. M.t D.traba, BaTgaamm, nnnobam.

In Praaa.

IB. Maartana, H., H.Baťtallnk! Plrat Btparlanea with tna Mlaro-aalaatroa lm Brwa*t

Conaarving Tharapy Implanta. In! Braahytharapy 1984, ProaaaalngH 3r* Intamatloaal

falaotron Uaara Maatlag 1984, Krag! K.y.Momla, TubLBnalatran TT*41ng BV, taatwwai

1963. p. 271.

11. Piarquln, *., A.DntraH, O.H.Taina, D.OHaoaagM. CnarHallw. E.Aa*! Tha

rla ayataai In lntawatitial rUlttian thaMay* **** Ka41al.0a)aal. 17 (197B). 33.

12. Plarsum, N., y.**Ulwt, J.T Wilaam K*ái*M<n MMra#y ** tHa MH<gaH<n% a

- l i t .

prlcary br*»*t e*no«r. i*»r.J.Rotntg«nol. 137 (IS?*), <45.13. Pl»«iutD, a., R.Ow«n, C.IUjlln, T.Ots»*guln«, V.0*70*1, V.fetiallar, S.Baa-

DOUDI Radloa.1 radiation thtrmjy of br»a»» «ace*r, lat.CBaaiat.G&ool.Slol.Phya. 6(I960), 17.

14. Rott«, K.t l.XAfflan Strahl*stk«rap*atta*fc* M*gllchJt«ltaB bn dar l i b u i *lvuic 6«s prt»Mr oparablaa kaaaafcanlnaa*. Oynlfcal.Prmx. 10 (19S6), 69$.

15. Sonul«, U.M.Buaoh, U.Boraanni l&tantltlal high tota-rata bra«hythar»j>l*iPrlnolpl*, praotloa and first olinlaaj ax»trl«ft««f wi»k • a*« rw«t»-oaotroll»taft*rlo«Aln« i j f i tn u*ln« Ir-19*. lnt.J.t»«i*1.C»Mol.ll«1.7kj». 10 C19M), 915.

TOR EARl-lt PETtCTIOf01 BREAST C1HCER3

Wolfgang 3ohfll«rRadlologloal Clinic of Dl»trlot Boapltal Karl-Marx-Sta**,0• mail Daacoratio Rapublle

of »arlj it i |*< of Ma»a ouolnoM Is a dlffleult probl«a. For tbadlagnoelo of patient* tha carliaat dataotloa of maaaa tuaoura 1* <3«O1«1T«, a* tk*•urrlral rat* of th* patla&ti> dspaoda atronflj on tha ataga of th* tuaor. at «hl«kth* traataaut «tart*d,

Baalo Lnraatlgatlon* for dataotln* braaat oanoax* ara ollalo and rafliologloal•athoda, •apaolally aaaaographj. In aacsocnuM aarly atatfas of oaaeara ara rapra-aantad bj T»TJ l i t t l * rarlatlana of aalaotad faaturaa. Only In fantura ooabLnatloaand rarlatlon tba phjaiolaa can raoognlaa a oanoar. But ba oannot *iplaln tha aatof data froa tha aasaograa If tba aat oontaiaa aora than four or flva faaturaa.

Tha **ourltj of dlagnoatlo daolalon at amrlj at«c*a of aaaaa tuaora aaounta taabout 60-70 paroanta at tha application of aaaaographj a» a aathoa of ebolaa Indlagnoal* of majna. dlaaaaaa.

k lot of lnvaatlgatlona hara baan oarrla* out to aupport tha a*41aal daolaloBprooaaa and to alnlala* tha riak dla^nkatle d*olaiooa by applloatlen af apaolalaathanatloal prooaduraa.

Hoat of tha dlaaaaaa raqulra a hi*h aartalnty of tha dlapioetla daolaloo a t l l lla an aarly stag*, baoauaa tha tharapautla atratagy ant tha prognoala of tha p*-tlanta dapanda on bara of In • high dagraa, aapaolally In tvaior patlanta. Tha aoctuaad aatbaaatloal aathod for aupportlng tba aadloal daalalon prooaaa in dl«gnoalaof aaaaa dlaaaaaa la tha BATES-thaora*.

Dlffloultlaa for that apaolal applloatlon araa arai

- alao*t only qualltatlTa- faaturaa aoaias froa rlaaal lotarpratatlon of X-ray•aaaograaa by tha phjalolan,

- aubjaetlra natura of tha faaturaa,- alaalsg aziatanoa of lndapaadanoa af tha faaturaa,

- a big nuabar of faatura»f

- a big noabar of olaaaaa laiagnoaaa),- -»»-g«i«1 eondltlooa aeo't allow tha uaa of atatlatlaal theory,- high fttiiinMi of faatara lnforaatlOB,- high unaartalnty of tha dla«noatla aaolalaa at waak faatura fraaaatatlao.

- 117-

A* a rwault of th* tntlyola oř th< r<c<ot l<ysí cf uaícg cn!)e'=.mctl methctz

for supôrSÍDg th< 4í<.gso<ía. *s <íp<rt #y<t*3 <ap*clally řor th* proH#a cf nma.-

ma dtagpoatlo wa,< áeT<lep<ď. &p#rt <y<t#=# art !h* flr<t pt-s-cHea^ly ueitH< 3-*-

aulta of inT«tlgntlcna about artifloitA íoHlHgcr.c^. Tb^y ccttaíc orgfml**ť tcnv*-

l<d;n about tha apaolal application flalč, !h< ec e<tll#í *Tpn-t jECOTl<ďg*. TRla

ia a collection of icoooladga, f*cta <mč č*t* M ^<11 *# preblot tclviag tutboťř,

rul<<, proc<íttr*<, to whloh * a#ab<r*hlp- cr <u.ee<<<-Frcí;<b!]Hty í< ol*#<t<iť with.

Th<« prob*bllltl## orlgtn*t* from tnt#raotiv< problu <c!vím.

Th< av<t tttportmt fonM of tmowUaůg* r#prmnt*tícD ín říp#rt ayatout *r*

- th* pr<álo<t< ealoulM of tha flrat 1<T<1,

- tha a<3*ntlo oat,

- tha rročuotlon* ay#tan,

- ffstaaa.

Tha aoat laportact of tha toâj *!latiag aaúleaj azpart wyatatca *ra cl*ř<lfí*í

ín ti<a folloaía^ tablan. Whiia tba tEQMlaúâ f#praawot*tiea í< číff*r*nt im tba

apacial ayatatM, tha lncludaú čaoltíon atratagla# M<* prvbtblUtí** agá íba ÂY^S-

atatiatlo for tha daoíaloa fladim. It la vary úlffíowlt or In *aat of tha ca#*a

latpoaHibla to datarmina tha#a preb*bllltla# in a eempl*! form, rut #v#ry ayata*

1* only a# good M tha at^l#tla#l t*lidlty of tha wyttae.

Tha bigg^'^ dlffloultlaa in eomtruotlzg âdlo*l #:p#rt ayatani *rl** fyQ^ th#

coawtruetlon of tha toaowltdga ba#ia. Tha abova aantlocať fttma or <a3o"i#aâ r#-

praaant*tion uaad *t praaant raquira a aora or laaa #trcng adaptation of tha da-

ta to tha particular *ho*an prooadura. But fu*sy ttno-ladâ about tha patlwat

acd about tha aadloaJ connaotiona ia wall *eoaptad li! aedlotma seč ta pbattâd aa

to ba inharant in it. Tha phyalolan takaa It into conaidarttlon hia ťally -orit acd

la *bla to dr^w loîoa^ oonoluwlona out offutay or unaharp faeta. řuttyr-#w !!-

aalf la information for him.

Tha thaory of fusty aata, daralopad In 1965 by ZAPEB, aaJtaa poaaibla tha dafl-

nltlon of unah*rp madleal faot# aa fu^Hy aata. Tltb ita hřlp a llngulatlo eonoapt

for tha formulation of lln#ut*tto atataaanta Jan ba oocatruotad. Additionally it

ylalda * thaory of fuaay logic.

Tha applloa^lon řf thla thaory la azpart aytta** to oocatruot tha jcnowi tg# a*-

ala and tha 4aol*ion atrata^laa puta attoh ayataaa to * qualltatlva hlghar Iwval

aoapared with tha abova mantlonad ayata**. for thay *ra an adaptation of tha prc-

aadura to tha ra*l, non-oaoaaaarily atandardiaad mtdlaal <!ata.

Far auppoyttat tha phyatoltn wa hwva davalopad tha ooaputar-aaalatad aTpart

ayatam MDIMA on * oomputar ayatam HTWLZTT-PACKAUD 9045 B in tha prc^raotmln^ lan-

guaft BA3I0. Tha aypart aywtaat la ba#ad on a^fma^y oonoapt.

During tha laat yaara wa davalopad on uniform pařamatrio manbarahip function

ooneapt. Wa pyafar it bae*u*W!

- Today a ayallabla oompntaM don t wort fuatlly. Tharwfořa thay oamnot m«aipw-

lata mambar#hlp funotion# in a fuaty way. PMomatar laval ta battar for aa aff+otl-

va haadlina;, howavat apaolal afgr*t*tioa *la*"Ti*!*M *r* na#da<.

- Wa gat am axtramaly high data rwduotlon faotor with tha ptrmmttrla cottawpt,

aut it la BMaaaayy to uaa a apawlal aoáwl. 3e tna ooaaay% la vaty aultatla far

<aaorlatlaa wf vary hlga #l)Maaiw<al Bamaaraalp fuBotlam (pFwatlaal ta ;oo)

- Tha aaalgaataat of aaaarata lnfoiaiatlon to p*r*mata!* la peaalMa.

- Tba function of tha aaaja typa aan aa aaaá for 4aaerlblag a*th alamantmry m -

foyamtlon (objaata or patlanta) aa< gloaal aaaa (altaaaa ar 41agaaaaa).

Oar aonoapt la a ganawliaatlon of A U B M A a potential ibnatlam. Tha mamwazahlw

fmaatlam ha* a aa^*l poaltlon ^ a *-*4*analaaal faatmzw ayaaa aa followa!

Kmanatata!

a. la tha aaaltlas af tha Tay**a***a** *f a #lw^**r

- lie-

a ia !Re s-MÍJtu* Ttlm of St* cnbtř<hip fsôUtcn.

ř! í# a f^^íor that í<!<ynÍB<a tc* TAltu ^f th* t*tt<r<hlp fJtotios *t th* thtrp

be^-^ry c of tč< olûta,

o í< :&< boují&a.r? of th< oltaa,

í í< *e ioforâticc papmtar for ď<ern*< lo t^nborahlp with incraní.og íí#-

It ía datawttaad froK cbjaat ííatributiom. yor d — c o wa gtt tin orůínajy noe-

funy a*zb*!*ablp fucotioa a# * apcelttl o M t .

TR< futty ítaotfl<d < bM< h*# th<* feUcwiet p^rMt<t<r#: 16 r*&tat!*.phle f#^tu-

y<#, 15 n*!ttf^l o l M t m , :ea,mt<č by t hí#MircbleAl olu*ítr ^<tbeč, th*t r*pr<-

<<at 6 Mxintio c l * # m . A l**rotag *pot-oh*et #<# u<<4 řer It coatitííag of 161?

p<m<nt< tn -ho* th< fta*l íl*ô<í< wt# imotm frax hlwtologle<d w:<M;Í33*ti<ae. TMt#

6 HMMmtlo ^1*#<<# «cele<# 39 #itbeíMH« *BÍ tb#y wwr# een#truet*ů through *n*ly-

#1* of tbs nptrt !m6řl*ú^# of ths ytty#ielMK suing HtLFHI <nthoť#. qMMtloo*tr*

H#tbed<, peettt- <*«<ton <ssí bf#4m#torHiag <ntheí#. Th*y *r*

clA t< 2: <il <ort< of

el*#* 3! Îí #ort< of tuotgn

ol##< *: A U aorta of a*Hga tuaora

cla*a 5: flbroala

elAaa 6: til cthsr auoelaaaaw, for *Taapla Mtitl*, tubtrouloaía.

9? a<nna of nitrsrc&ie*! aluatay *aajy#ía 15 naturel el***a* v#r# íacl^tad out

of th< latmiag #pot-^b#o!t *hioh *y# olam to thaâalf, l.a. only patltnla of tha

aa=* M=tantie ol**e. yor *!<apla, a# a. wubatruotura wa eaa Clattng!ít<h for tba w#-

oantío ola#a *AH aorta of bánit? ttmora* tha fibrotdano** amd tha oyat w# *ap*-

rata noturAl olaaaaa acd ta tba aamtmtle eltaa "All aorta of xally: tumora* wa eaa

ťlffaraatiaía &řtw#an acllá aad clrrhotla oa^relcoâ. It la atao poatlbla tc fla<

natural cl*#aaa which cavmot ba daficad by tba phyaloltn. Raa#oa oac ba untuMme r#-

latíonwhlp of the fattm** ícaw aycdromaa) or f*lluraa of tha elowalfiar aaalga

proeaaa.

To u*a tála fucty toaowladga b*aa wa b*v* oonatruetad * fussy ol*aalflaT. For

a givan pitlant with th* 18 yadiOtH^phlo fattuya* # aympathatlo v#etor !w 6at*r-

atíoad. Tlth Ita ooaponanta lt glvaa a dtffaraat aambarahlp v*lu* or affinity to

avary of tha 15 natural el***a*. Thla la tha Important dlffaraaoa to tha eoaawB

atatlatical declalon prooaJaraw. Tboaa glva only tha nawbarahlp vaûa to eca tao-

latať el<*#a.

?ha daciaíon for * particular dlagnoala la amůa by tha phyttotam acoorďlng to

th< hlghsat ayatpathatlo valua and tha naxt-hlgh. Ic gaaarAl at*tlo 16antifle*tloa

ia snad. íf lt 1# not poaalbla to gat * ol**r ďaolatom, a oontrol axa*lnttlon of

ta< pattiant bacooa* naea*a*yy *ftar * cartaAa tlnja. By eoap*rl*oa of tlma labala<

ayspathatlo vaotorn * Qu*al-dymami<! idwntlflo*tlom aad aoaíatlma foraeawtlng ia

poaalbla.

To MtuHlta tha kmowlaaga bMaa wa hava daralcpad <m inatruotloaa,l *odul. It

*llowa to claalfy tba birth and d**th, to *ap*r*t* tha olaaâa amA thwlr malting

togathar. Al#o * mamory la eonatrootad by ualng potaatlail přoduet amtlva pe^#r

funotloaa cut of tha avolctlonajty thaory.

Tha *pot-cbaok of 1492 pttlaata ahaaam *t raníom ylaldw* for car ttuty clařl-

flar * hlt ^robaMllty of ocra thaa 95 parwant ##p#olailly for th# oorraet aaaigm-

ajant of aarly ataga# of malign tanozw, which war* eonflznad hl#tol#gically. For

* H othar tbora-auntltma* fo!!na of ar#*at *laaa#M tha hlt probability - M hlgh#r

than 96 paroaet. Tha astpart ayatax D U M * with f&Ksy ayataa! osnswpt for aarly oam-

a#r 4at*etiom of faoalw bra<#t ha# a*a* Htra<aM4 la yTMtla*. 9im## Ita

tatlaa abomt 6000 patlaata wtra al*##lfiaá. Par aHniwal nwa wa **r*

-13.9-

y*i*= ca tt< CM< of only 12 f<ttnr*a <Lní 4 <<meotí.c c l t m * íporn*!,

*'jL«p*3t. ť-taort, b*ci^: Hle#*<; r*pr<*tat#d bj íí s<!ur^l eít<<*#. Te ímprcr< th*

r##uit o? th* ííc:::fí<:*:ícc It ia pe#albl< ío et^bítu 3p*ol*l fu*nj elmlfi*y#

to ol*<*ífío*tor n*tw. Th<a lt ia poaalbl* to eczblc* ola#ťlfíeator# fer úlff#r#Bt

tnvettlgitiesa (for <xaaipl* of &ia,^:oala of wtam tmor<: cembin^tltia of olintetA,

r*íiogy*phlo, thmtogr^phie tnd ttltr oticí lDT«tigm.cn<) to oí<##lflektora for

dí<gso<i< atr*t<gí*<, but <J.#o to tmlqsn el**<ifit?t for «ptr*t#!Lj ohcmB fM.tw-

r*< of cn< Í3T#<tigAtlom.

Th< <ip*rt <y<tM) DICDU ecat*ina ÍJO th# l<^t aA<djaia * *oíul to thow fsurttur

dl*^!O<l< or tb*r*py Meta on th# b**l< of th* hith^rtc ř*As č#ei<ion<.

Tht phj<le^*a CM! eorrw<poo4 tat<r^<tlT*ly with th* ayttt*. Tb# c^c<tí#tlan ti*

a< to lá#atlfy * p*tl*at t*K# !<## tUn c^# Mtcn<.

To u<# fua<j <!<t))o4* la n*ét*ti#a t)t<rtpy #% h*v# tmmtit**** t^< following

pro&l*a<<

- Control *f progm# *řt*f MáH<t«t th*y*ty t* g#t i*f*m*ti<^ *^#u$ t u '***-

ao#i< oř p#tí#nt<,

- to <#l#at th* oytijnl thtrtyy #t<wS*<y <*ni**!lat *Hs o t m *f th# p*ti#m^,

- to <*pl*ln r^41w#i#l*^laaA #ff#wtw t* #wn^Fta# with t!**itl***l *tKl*M#<A

M*tho4*,

Th< first r*<ttlta wiU h# pMbH#h*w 1* th* B*it w<*)c<.

1 0 - 5 0 MtT MDICAÍ MICROTMM

Run* W*l<t«t,

Departatnt of RndlHtíaB Phy'^w*.

NOT 602M, 3-104 m atoakholn. 3-#d#n

Introíuot^on

I had th* pl*a#nrw of p*rtlalp*tim tn your *Flr#t Sy*potlu* of R^dlolotíc*.l

Phyalol*t<* ím 1961 and to pr*«nt * P*P*T "Th* prop*yti*a ef 5 - 50 M#V Madlc-1

Mlorotrona". It la aprlvilagw to h*va baan aakaí *t thi* ooafaranoa to praaaat

a, auamry of olínloal aTparlancaa with tha*a alaotroa #onal#ra.toTa.

t/f tha aoaaditroni* daalga hzva baan ia#*aAlad aiaoa 1974 lz hoapitala lz **nro-

pa, US* and Japac two 10 MaT anlta, thraa 14 MaV unita, a H 22 MaT unita aed - quita

raoantly oaa 50 MaV raea - tnut miorotroa *t tha uaivtiwity of !!^a* ia oortham

awadan - thaw quitt faw of atwh typa. Two 10 MaT unita and two 22 M*V unita aLra

working at dual **ntyy tMt*U*tloa. Ona hoapital, 1* <y*aai* í* Italy, haa two

lMtallation*. tha dual gaatzy 10 KaT unit tnatallad ia 1974 and ona 22 MaV uait

iaatallad in 19H3.

In thia pyaaantation I woaH lHf# to liaawu tha optiaMiíH of tha ba**, prinal-

*al daala^), proyartlaa aad fnrthar i*)př*v*a!*at* oř *adlo*l mi*rottona and auHtaarlaa

t** av*llabl* infoj}H*tion ř* <Lř6iaj[ th* p*rfo<waa** o< *o*)* *limi**lly lnatallad

wnit*.

Whs — - — - i * - * - thatamv T

<igh anaygy ghjgiggg hav* th:wa di*tin*t adv*Ht*t*w aMah H*in*lly *ř* andarllaad:

1. BMM**** panatratl*- for lr!%*i*tiaa alwo of daay^ <it*é tMgata.

- 120 -

2, More homogeneous doss distribution In different kinds of tissues.

3. Build-up of the absorbed doaa whlob means a significant reduotion of the

radiation effeot on the atin and - at high energies - also of subautaneous tis-

sues.

In addition oan be mentioned the high radiation output whloh makes the irra-

diation time convenient also at long souroe-skln-dlstanoes required for large

field* and inoreased relative depth dose.

Two disadvantages as compared to ortho-voltage oan be noted:

1. The built-in dlaphraga system of high energy units have generally restric-

ted the beam shape to rectangular forms, while in ortho-roltage therapy It was

possible, for instance by means of lead-rubber, to tailor the alia of each field

to the projeotion of the target volume In the beam direction. It is not unusual

in routine megavoltage therapy that the beam size - and aooordtngly also the ener-

gy imparted - is 20-30 percent larger than neoessary due to these olrouastanoes.

The problem is partly overcome by using individually oonstruotad bean shaping

blocks. Suoh blooke however are time consuming and elaborate In produotion, heavy

and oumbersome in their applications and diffioult to ohange If required during

a radiotherapy series. Attempts are therefore made nowadays to produoe more fle-

xible diaphragm systems whloh oan facilitate the procedure.

'£. Orthovoltage radiotherapy allowed therapeutlo irradiation during continuous

fluorosoopio control. This method permit-ted the operator to adjust, during rota-

tion of the patient, the position and siee of the beam to the actual target pro-

jection. At high energy photons this teobnique might be replaoed by more elabora-

te "conformation" or "dynamlo" therapy.

Comparison of photon beam qualities are frequently based only on central axis

depth dose curves. Simplified Intel-comparisons based on the addition of suoh cur-

ves for two opposing beams and various thloknesses of the patient do not always

give the proper answer. As demonstrated by Janes Ssengabi also the penumbra con-

ditions must be taken into aooount. Advantages and disadvantages for various ener-

gies ar* also depending on the site, else and shape of the target volute as well

as the type of irradiation techniques used.

The build-up of the absorbed dose, whloh is a considerable advantage whan ir-

radiating deep sited tumours, might be disadvantageous If superficial tumour oells

are present. This la frequently the oaae in irradiation of lyaphomaa, breast car-

olnomas, tumours In the head and neck region as well as metastasis In various a-

reaa. The build-up depth also varies with the angle of beam inoidenoe and it is

ntcesaary to make more detailed studies than just considering perpendicular inoi-

denoe of clean photon beams on a flat water surface. Two clinical areas where tola

is of particular importance is the tangential irradiation of the breast and the

neck region. The studies of James Ssengabi illustrate how the skin sparing build-

up effect is depending on the energy of the photons, the angle of Incidence and

radius of ourvature of the Irradiated tissue.

In a reoent evaluation at our radiotherapy department for the replacement ot

old therapy units we oame to the conclusion that In prinoiple we needed photons

in two different energy ranges. 4-8 MY photon* are preferable In the treatment of

aead and neok tumours, tangential Irradiation of breast carcinoma, lyaphooa* ate.

where the build-up region should not be too deep. 20-50 Wf photons are preferable

for other applications, suoh as deep sited tumours In the thoraoio or pelvio re-

gions. The number of patients in oaoh of these two groups Is estimated to bs appro-

ximately equal.

High energy eleotrons are expected to be useful for many tumour locations. Their

general application has probably bean Impeded by unsatisfactory beam quality at

many units and the dlffioulties in treatnent planning, particularly In areas where

- 121 -

air cavities acd/or compact bone er« present. In view of the new developments In

ollnlcal electron dose planning we think that aleotrons will ba uaad more in a

near futur*. Our conoluaion ia that single field* of eleotrons of energies up to

25 MeV will beoome more useful. Whether even higher energies will be benefiolal

Is atlll an open question baos.ua* the advantageous ateepnesa of the depth doae

ourvo Is deoreasing at higher energies. These high energy eleotrons are most use-

ful In opposed or multlpl* beaa techniques and oftsn In combination with photons.

Eleotron oolllmatlon was until reoent year* generally mads by aeans of fixed and

quit* heavy auxiliary diaphragms. Today variable diaphragms are available and thus

the flexibility In application of eleotron Irradiation is improved. Intraoperatl-

ve Irradiation with eleotrons seems to be a promising treatment sodality, also

for tumours where radiotherapy has offered very little until now.

The principle of tha medloal mlcrotrona

The prlnoiil* of the miorotron was described In l'J44 by the Soviet physlolst

Vekal*r. Miorotrons for physloal researoh facilities hava been built and instal-

led from the 1950s and in the 1960s the miorotrona were proposed for Industrial

radiography as well as for radiotherapy. The main advantages for radiothorapy are

the high radiation output - similar to linear aooaleratora - and a narrow electron

energy spootrum, like In betatrons. The latter oonditlon makes it possible - by

means of magnetlo foouslng and bending systems - to feed through vaouum tubes, •*-

veral irradiation facilities from on* single aooelerator. It also means that the

rotary gantry of a radiotherapy unit oan be made simpler, lighter and more easily

moveabl*.

The aooeleratlng prinolpl* of the miorotron Is that eleotrone of atepwise ln-

oreaslng energy are moving in oiroular traoka In a permanent magnetlo field. The

aooelerator and the therapy gantry oan be placed in different rooms. In Breaola

for lnstano* on* 10 MeV unit Is feeding two gantries, with eleotrons transport

distances of the order of 15 meters.

The olroular magnets of 10 and 14 UeV mlorotrons are of reasonable sis* but al-

ready at 22 11*7 the sis* of the aooelerator becomes vary large and heavy. However,

with the design of the raoe-traok miorotron (Waistam 1983) It la possible to bring

down the weight of a 50 MeV aooelerator to a few thousand kilograms. A researoh

unit of this type has been in operation for a deoade at the Royal Institute of

Teohnology in Stockholm. On the baa la of reaearoh experience the first olinloal

rao*-traok miorotron was built and Installed last year at the university of Unea

in northern Sweden.

The very first nlorotron was equipped with an ordinary diaphragm system but

attempts were nade to optlmlie the design of the I-ray target and flattening fil-

ter as well as eleotron scattering devises. Subsequent miorotrons include indepen-

dent adjustable oolllmator Jaws In order to make possible e.g. off axis rotation

therapy and an improved alignment of adjaoent beama of photona and eleotrons of

various energies. They have dual or multiple photon energies and automatic *ual

wedge saleotor - all developments whloh have been published.

Reoant miorotrons developBents

In addition to the installation of tha first olinloal raoe-traok miorotron two

main developments la reoent years oan be noted. To* flrat ia oono*rned with a soan-

nlng beam teohniqu* whloh la prinoiple m outline* in my previoua preaentation.

Th* seoond is th* darelopMnt of the doable foonaed multileaf oolllmator whloh of-

fers advantages for fixed b*aa therapy aa m i l M for ayaaml* beaai therapy.

- 122 -

The spanning bean ayatom has dual magnet* aoannlng the b«aa In two orthogonal

dlreotlona. The system baa b«en tested by computer simulation a* wall aa In an az-

parlmental aet-up on tha raoe-traolc miorotron at tha Royal Instltuta of Technolo-

gy. With th» newly developed technique it lo possible to execute:

beam flattening and compensation,

beam oolllmatlon,

absorbed dose and dos« distribution monitoring,

patient and oolllmatlon Monitoring.

All these goals oaa be aohlored by the sane computer oont rolled teohnlque for

eleotron* and photons. An example ol the wodge pattern that oaa be obtained ia

given In fig. 1. Tho diagram illustrates in prlnelpla how one narrow beaa by a

Lateral dlslauce Lateral distance

Calculated dose profiles for wodge-flelds with an elementary Gaussian profile

(upper) and utilizing a filtering function (lower; according to Lind and Brahme

(1985).

soanning procedure can simulate the ef-

feot of an ordinary wedge. The wedge ef-

feot oan be obtained by two different

prlnoiples: either by changing the am-

plitude of pulses aa they are given at-re

regular intervale or by using the same

pulse amplitude but change the dlr*incs

between the pulses. The same principles

can be used for compensation of body con-

tours and body inhomogsneltles aa well

as for adapting the depth dose distribu-

tion to a partioulax target orientation

or depth.

The principle for the double focused

multileaf oolllmatsr is illustrated on

figure 2. As illustrated it is mounted

within a sealed treatment head, coa-

talnlng helium, in order to reduoe the

eleotrea soatter in the Irradiated gas

volume (normally air) whleh ha« beer:

shown to oontrlbuta largely to the soat-

The prlnolple for an advanoed BMltileaf oelllmater syatoa (aooording to A.Brahojejt» bo pukllshod 1987). 1.9ul " - - - . - -r»3. Dos* distrlbutie* •onltor»atsjosphere.

soanning magnetst Z.Fhotoa boaji porgiac magneti4* Wultileaf oelli«ater a*d video readout| 5. EtUus

- 123 -

ter In the beam reaching the patient. By means of a purging magnet the photen

beam oan b» effectively oleaned frem electrons from the target.

Tha multlleaf oolllmotor oan b« controlled by a oomputar and Individual motors

for aaoh leaf. It offara obviously possibilities of tailoring the beam ahapa to

individual naada and to uaa the oollimator In eo oallad dynamlo radiotherapy. Tha

oolltmator Bight also offer possibilities for a CT-slmulating prooedure to oon-

trol the bean poeltionlng with a radiation quality equal to the aotual therapy

beam. Investigations are under way to oheok thla possibility. Reaponalble for tae

development of the new oolllmatora has been aaa. profeaaor Anders Brahne and oo-

worlcera In Stookholm. The adaptation of the a ye tea to the olinloal altuatlon la

preaently carried out at the Urnes1 Unlreralty Hoapltal under reaponsiblllty of

profeasora Han a Svensson and Bo Littbrand and their oo-workers. A aeoond 50 HeV

raoe-traok system will be inatalled at M.D. Anderaaon Hospital In Houston, Texas,

in the beginning of 1988.

Exparlaaoes

Quite a few papera have been published regarding the experleaoes from ollnl-

oally Installed miorotrons. In summary theae reporta verify that the phyaloal

propertlea of the photon and eleotron beams from the mlorotrons axe superior to

or at leaat equally good aa from linear aoceleratore and betatrons.

High quality of the primary eleotron bean and optimised design of the treat-

ment head oontrlbuta to Improred depth doae ourrea - inoludlng the build-up re-

gion , better ieodoee ourrea and field uniformity alao at larger depth. The con-

tamination of the treatment beam* with eleotrons or photons reapeotlTely as wall

aa the neutron flux has been lnreatlgated and found to be well within reooaaen-

ded limits.

The dual or multiple photon energies are frequently advantageous and u wide

range of eleotron energies facilitates lndlridual1cation of irradiation. Pour In-

stallations have two gantries oonneoted to one accelerator. Some of these gantries

arw specialised for different purposes; for lnstanoe one treatment room mainly

for photon, the other for eleotron therapy.

Two of the 22 MeV Installation hare epeoial arrangement* for lntraoperatire

rsdiotherapyj some treatment rooms bare Arrangements for whole body Irradiation.

Ergonometrlo faotors have been considered in the design of the rotary gantry,

the auxiliary eleotron oollimatore, the treatment oouoh, the oa11 Ing mounted ma-

noeuvre station and the oontrol panel eto. It Is also verified by the operational

staff that in these respects the mlorotrons perform very well. The accelerator,

the gantry, the treatment oouoh and the oontrol panel oan easily be oonneoted to

a computerized rerifloatlon system - an aooessory whloh is almost a must for qua-

lity aasuranoe In todays radiation therapy.

a n d reliability

Tor the routine ollnleal work the maintenance requirements and reliability of

an eleotron accelerator are obrlously of paramount importance. Howerer, In the

stage of development researoh ollnlos might be willing to some extant to partici-

pate in the testing, development and olinloal adaptation of new and complex equip-

ment In spite of possible lnoonvenlenoe and development expenditure. Some of the

early users of madioal mlorotrons had this ambition. It is impossible at an early

stage to make fir* oonoluslons about reliability under routine work oondltlons

of a prototype equipment. A few observations based on published works and judge-

ments from individual mlorotron users might however be of Interest.

The two users of 10 MeT mlorotrons, which have been in olinloal operation for

rather Ions time and both a m using a dual gantry installation, have reported po-

- 1 2 4 -

sitive experienoes. The unsoheduled down-times have bean reported to be of the

order of 1-3 per oeDH over many years of operation. The dual gantry ayatam of

ooursa involves apeoiaJ. down-time problems beoause two treatment rooms are lost

during accelerator failures.

Por the MM 14 units six years statistioa ia available from on* unit tn Finland

inďioating an annual unsoheduled down-time averaging to 7 par oent.

For the MM 22 unita the experienoea are aoatterad. For tha first unit installed

in 1978 in UmeA tha unaoheduled down-time was about 6 pay oant for tha firat year

but deoreaaed aoon to leas than 3 par oeat. Om' o!fn MM 22, installed and teJten

into operation during 1963, showed under the garantee period many unexpected break

downs. The garantee period was therefore prolonged. During 19S5 tha unsoheduled

down-time was in average less than 3 per cent. We have reoently experienced sons

new problems and an inoreased unsoheduled down-time. We are presently disoussint

a now preventive maintenance prograH, apejre parts supply and other questions re-

lated to the improvement of the reliability.

!<r long time reliability reports have been published for other MM 22<s. Aeoof-

dlng to the manufacturer they have reported only few unsoheduled break downs and

technical complioations. It oould be noted that in some of these installations

apeoial treatment techniques and a fairly low rate of patient irradiations have

baan anticipated.

Conclusions

A range of medioal miorotrona have baan produced during the last deoade. They

are characterized by an intense high quality primary eleotron beam - whloh can be

tranaferrad to multiple irradiation facilities. The development of these radiothe-

rapy unita has alao involved significant improvement of target and beam flattening

davioes for photons, aottterer* for elaotrons, a scanning beam system and a double

foouaed muJtllsaf oollimator. Theae new technical developments make it possible

to improve the doee distribution at existing techniques and also to develop new

irradiation methods. Medioal miorotrons offer operational advantages beoause of

economically optimized deaign. Until now only a few units of each type hfsve been

inetalled and moat of them have not been in olinloal use long enough to allow any

firm statements about long tsrm rsliabllity. Most of the users seems to be satis-

fied alao in this respeot - the unscheduled down-time being of the order of 2-10

per oent in average on a yearly basis.

References

Ssengabi J.! Studies of photon beam properties in therapeutic applications. The-

ses, Department of Radiation Physios, Stookhol* 1978.

Walstam K.t The properties of 5-50 MeV Miorotrons, Aktuality t Ulnlckoj onkolo-

gle 4, Bratlelava 1983, p.3S.

Lind B. and Bfahne A.t Qeneratioa of desired dose distributitas with soanaed

alemontary beams by deaoavolutloa methods. Med. and ntel.ň!*;. and Oomp. 19M, vol.

X3, p. 95).

Brahma A.< Personal eommunloetlon.

- 125-

KOBALTOVá OZAňQVAČE - VČERA. DNES A ZÍTRA

Pr*ncl L., Kubeo V., Zámečník J.,

Radiottrepeuticky úetev, Prah*

Úvod

Hlavním léčebným proatředkem větílny radioterapautlokýoh praooviít nejen v

JS3R, ala í v* avětě, jaou dodnes kobaltová ozařovače. 3vé ooenění necháte jí i

na těch praoovištíoh, kde se v poslední době uplatňují tdroje vyaokoenergetlcké-

ho záření I, elektronů nebo 1 neutronů.

V aouviHloatl o výstavbou ozařovaoiho traktu Radiotezapeutiokeho ústavu v Pra-

te, jejíž ukončeni se předpokládá v r.l9BS, jame byli poataveni před otázku: bu-

dene v r.1990 a dalěíoh letech nadále pouíívat kobaltové ozařovača, nebo tyto bu-

dou nahrazeny jinou ozařovaní teohnlkon pro l4čbu zhoubných nádorů ? Zhodnotili

jame naěe támář třioetilatá zkuíenoatl' * ozařovaní* různými typy kobaltovýoh osa-

řo?aía (OUT, Chiaotron, Chiaobalt, Chlzoatat) u víe# jak 20.000 nenoonýoh.

Souhrn poznatků

1. Relativní výhody kobaltovýoh ozařov*6ú (v# urovnání a lín. uryohlov^ i 4-6

MeV):

- relativní jednoduohoat

- anftdná obaluha

- anadná údržba

- snazáí kalibrace a dozimetria

- nízká poruchovoat

- men;i stínící požadavky

- dostupnost náhradních dílů

- nízká spotřeba el.enericla

- žádná spotřeba vody

- meněí kádrové nároky

- menší pořizovací, inatalačni a provozní náklady

2. Relativní nevýhody:

- niiši dávkový příkon

- nlžěí kvalita avazkut záření

- nižěí výtěžek hloubkové

- přítomnoat radionuklldu Co znamanajioí

a) aožnoat vzniku radiačních nehod

b) zvýáení radiačního pozadí (mimo ozařovaoi čaa)

oj problémy apojené a likvidaci zářiče (peče o ílvotní prostředí)

Uvedená nevýhody (zejména poslední) va*k nevyvaíuji zpravidla řadu výhod, tak-

ía kobaltové ozařovača nacházejí uplatněni zejména na radioterapeutiokýoh praoo-

vlítíoh těoh zemí, kde ja omezena technologická lnfraatruktur*.

3. Světové trendy

Počet kobaltových OBařovačů běhám minulého desetiletí ve světě naastále roatl

a jenom např. v USA pracovalo v r. 1981 vic# nač 900 těchto přístrojů.

Nejvótňím výrobcem této ozařovaoi teohniky je ve arětě kanadská firma ABCL, kte-

rá od r.1951 dodala do vioa jak 50 zamí kontlnantů vio* ne! 1.700 kobaltovýoh oza-

řovačů. Pro srovnání uvádíma, ša v r.1983 bylo va světě instalováno oalkam 1.400

llnaamíoh urychlcvačů, z toho a*l polovina v USA. Věhlasnast firmy A K L ja zalo-

ían* na vysoké spolahlivosti * přesnosti přístroje, jeho airokeno vybavení, jtkos-

to i na parfaktním servim. JadnÍH z posladníoh modalú této firmy ja i Therttren

780-C. Z významnějMeh jaho tsehaiokýoh parametrů uvádíme:

- 126-

-4 -4

exp. vyd&tnoat zdroj* záření - 8,6.10^ A,kg (12.OC0 Rhm)

vtdálenoat SAD - 80 om

vzdálecoat SDD - 45 cm fixní (55 cm odnimatelná olona)

velikoat polí v SAD - 4 i 4 ař 35 i 35 om*moínoat vybavení "baamatopram" (absorpce 99,7 % záření)

izocentrioita - do 1 mm

4. Stav v ČSSR

Ve státech RVHP zajiSťuje dlouhou dobu výrobu kobaltovýoh ozařovačů k.p. Chi-

rana Praha, který instaloval v Č3SR a zahraničí (NDR, PLR, MLR, Rumanako, Kuba,

Vietnam, Turecko) vioe jak 50 ks ozařovačů typu Chisobalt a Chisostat. Tyto ko-

baltové ozařovače, jejiohi prototypy (jakožto i některá další) byly odzkušovány

v Radloteyapeutiokám ústavu, jsou víak a minimAlmími úpravami vyráběny od r.1966

a jsou tudíž saatarale*, naaplčujíoí poiadavky modtmi radioterapiw. Vzniká tak

akutní potřeba jajioh urychlená imovaoe na základ! lákarako-teohniokýoh počadav-

irů. řřipomínky uživatelů nebyly a nejaou atále výroboem ozařovaoi techniky v ČS3R

plně akoeptovAny.

Jednou z nevýhod ozařovačň Chiaobalt a Chiaoatat - nepříliš kvalitní svazek

záření - je možná zlepšit jednoduohou úpravou polohy lamel primární olony oproti

poloatínová oloně při současnem přeoajohování atupnio olon. Dojde tak k vy'razne'-

mu anížení poloatínu, prodloužení plato izodozníoh křivek a ke zvýšeni indexu ho-

mogenity.

Rovněž je zapotřebí zvýšit aktivitu zdrojů záření Co objednávaných ze SSSR,

a to na původní dodávaná hodnoty.

Součaané je zapotřebí zvýšit celkovou teohniokou úroveň daných otařovačů, zvý-

šit jejioh radiační bezpečnost a zajistit bohatai příslušenství. Proto je nutná

kláet zvýšený důraz na nedílnou apolupráol lékařt-radioterapeuta a klinlokáho r*-

diofytika a konatruktárem ozařovaoí techniky.

Závěr

Mnozí cdbomíoi ae domnívají, íe úloha kobeltovýoh ozařovačA v radioterapii

zhoubných nádord dosáhla sváho klitzajcu a bude zvolna ustupovat. !<y včaJc tyto ná-

zory neadílíme a světový trend potvrzuje, !e kobaltový ozařovač ai zachová svá

důležitá postavení v příotrojová* vybavení radloterapeutlokýoh praoovičt i v nej-

bližší budoucnosti.

Veškerou pozornost je zapotřebí soustředit na problámy zahrnutá v 'quality as-

surance", která jsoH medicínská, fytlkálaí, teehniok* a adminlstattivni povahy.

Kvalitní kobaltový ozařovač st(Hs ve srovnání s lineární* uryohlcvaBe* poskyt-

nout adekvátní nebo přijatelnou Iá3bn u 6? aí 90% aemoanýoh.

Samozřejmě ke koatplexnísM xkvalltaění radloterapie - a to nejen kobalte*, je

nezbytná rovněž perfektní lokallsto* nádoru (simulátor, 0T), klinická dozlxetriw,

plánování Iá3by (T3P) a dalM.

- 1 2 7 -

ZPŮSOB ŘÍZENÍ URYCHLOVAČE

?ŘI POHYBOVÉ TERAPII

J.Oohao, Základna rozvoje uranového průmyalu, Ostrov nad Ohří

P.Bednář, Radloterapeutioké oddělení nemoonloe, Cheb

Summary

There ia an Important queation of providing aocurate and ataggered doae during

arc therapy. To aolve thia problem tha angle of pendelum la divided in parta. Tha

oheok point ia plaaed at tha and of each part of tha angle and tha part of tha do-

se is oheoked there. Tha question of th* number of oheck pointa and tha way of

oontrol of tha aooalerator la also di*ousa*d. The reaulta of doaa measurements

as wall a* tha raaulta of tha real applioationa are given. The devloea for control

of the accelerator baaad on thaaa reaulta and aquippad with miorooomputer wara

daaignad.

Vyuiltí uryohloTtíA alaktrioicy nabit^oh čáatlo v lákařatvi ai4 tvyou.lioi aa trand.

Betatrony, linaámí uryehlovaía a v poaladní dob! 1 ttikrotrony produkuji avazek

vyaokoanargatiokýqh elaktronů o anargil 4 až 50 MaV podlá typu uryohlovača a brzd-

n^ záření 1. To vada ko kvalitativní změn! v užívaní zdrojů ionizujícího záření,

dosaňujw aa va arovníní a klaaiokými zdroji zářaní výhodnější diatrlbuoa dávky v

prozařovaném proatoru. Souíaan! a využíváním urychlovačů byla provedena oalá řa-

da experimentů a. taoretiokýoh praoí, která vedly k novýma poznatkům a novým techni-

kám při ozařování, ke zlepfení celkově přeanoati při aplikacíoh vyaokoenergetio-

kýoh elektronů a záření X, k novým konstrukcím dílů 1 oelých zařízení, ke zlepše-

ní klinioká dozimetrle a k zíakání zkuáenoatí a apllkaoí této teohniky.

Jednou z ozařovaoíoh teohnik, která přináší zlepšení, je pohybová terapla v je-

diném kyvu. Při táto terapii ae ozařovaá pohybuje tak, aby maximum účinku ionizu-

jícího záření bylo v žádaná čáati prozařovaného objektu a oatatní čáati, jako je

pokožk* a kritická orgány v lidakám t!le, byly taaazeny oo nejnán!. Zde hraje dú-

leíitou roli otátk* rovnoHimáho rotloíaní dávky v oelám Intervalu úhlu, pokud ae

pohybuje osařovaC, anebc v Intervalu polohy řízeného oaařovtoího atolu. Urychlo-

vač je viaJc zářič, který nedává konstantní dávkový příkon. Byl proto navršen ří-

díoí automat pro pohybovou terapii, který realizuj a řídíoi algoritntua naů.ožaný na

jednoduché mySlenoe. Při ko^atantním dávkovém příkonu at*M sajlatit konstantní

iáťaaoa ryohloat pohybu, abychom doaáhli rovnomámého rotložaní dávky. Kdyi ala

střední hodnota dávkového příkonu kolíaá, budaae tuto hodnotu m!řlt a příaluán!

korigovat žádanou ryohloat. Řídíoi algoritmu* potom počítá potřebnou hodnotu úhlo—

vé ryohloati ozařorača cv & a mění rychlost pohybu podle výaltdkA výpočtu dl#

hU!

kda /^ - konečný uhel IL * kon*čná dávka

/* - výchozí úhel D - ozářená dávka

/o - okamžitý úhel k^ - kotfioUnt měřítka

J - okamMtý dávkový příkon k - opravný koaflolamt

Osařování ukončí dozimatr při doatíaní hodnoty D - D^, nabof tento vztah

kvůli přaanoatl výpočtů a dvojnásobnou dávkou rozlaZtnou n* dvojnásobné drásá.

Tento algorUnus fungujs, pokud uvtzujame pousa skotcová nabo statická smány.

ATš*k při tkouskáeh raálné soustavy s* prokás*le, š* řaiení pedls původms valla*

jednoduohá myRanky vsda ks sloíltasM s*ří*aní, která je nároíná na seřizování s

a*stsvaní víesh regulsCníeh konstant jednotlivýeh Sástí, zvláště kdys uvazuje**

- 1 2 8 -

dynamloká obování * nutnopt vyloučení ohyby dozimetru, enimače polohy atd.

Proto jsta ae začali zabývat nespojitou neboli krokovou pohybovou terapii.

Použití táto metody nevede ke thoríení terapeutiokýoh výaledků, ala vede ke tnač-

námu zjednodušení technických proatředkd. Máme provit ozáření na úhlové dráte

mezi úhly V í * / ? * Tento Interval ai rozdělíme na n kroků a atvjně tak 1 eal-

kovon iádanou dávku rozdělíme na a paroiálníoh dávek, která v obecnám případě nw-

mu<í být rovnoměrně rozložená. Po odzářani první parciální dívicy D. - D. sa amě-

ru V i * ^i c**tane poaun ozařovača o dalěi krok, t.j. do polohy ^^ * ^?<

kde ee odzdří dalří pamtálni dávka D^ - D-. Pro atanoveni intervalu ^< * diHi

dávky mane moínoet aměy sáření polohovat do atřadu intervalu ^,, /i+i^ n*bc

.ářlt * hrtniíníoh bodd intervalů t/^. Cwlková aplikovaná dávka 3e dána aouítem

parolálnioh

pro druhý případ. '*'

Podle vaimi dobrých výsledků zkoušek a krokovou terapií Jane atejný prineip

zavedli i pro spojitou pohybovou terapii v jediná* kyvu, t.j. provádí** pohybo-

vou terapii podle výáe tmíněnáho vztahu, avšak záměrně jame tvětěill nepřeanoat

ayatámu a zavedli tzv. kontrolní body, ve ktarýoh kontrolujeme odzářenou dávku.

Mohou nastat tři případy:

a) ozařovač ae pohybuje takovou ryohloatí, i* v kontrolním bodě je přtami do-

aaíeao ahody žádaná polohy a žádaná parciální dávky;

b) ozařovač ae pohybuje ryohlejl - v kontrolním bodě muai Mtatavlt a počkat,

a5 dávka doaáhne žádaná hodnoty;

c) ozařovač ae pohybuje pomaleji - iádaná parciální dávka ja odtářená jaětě

před doaažením kontrolního bodu a táření ae muní vypnout aí k najblliaimi kontrol-

nímu bodu.

První případ, i kdyi by byl optimální, je uveden pouze pro úplnowt. Pravděpo-

dobnoat, ie n*#tan#, je vallo* nepatrná. V případě b) je víoa namáhána machami-

ka atojanu, v případí o) ae zae* zvyíuja doba pobytu paoianta, pod ot*rov*ča* m

zmenšuje ae tak práohodnoat praooviíta.

Při analýze těchto případů jáma muaell řeílt vliv ohyb, kttrá ovlivňují přaa-

noat 14oby a na která byohom nyní upcaomill.

f ozlmetr bývá řeaen * poměrně vyaokou vatupní int**-r*6ní koa<taatou, a*#to

1 a a i vioe. Jattlife v čaae t - 0 zapnama uryehlcvaC, který sačna Kářit kem-

atantni expoziční ryohloati H, je nárdat údaja dozlmetra podle obr. č. 1. Dc*l-

metr ukazuje expoziční yyohloat:

Uávka odaářan* v 3a*ov*m intervalu T Je pak dáaa vst*h*m<7*

ud*j je zatíSan ohyboa, ktará budataa říkat počáteční chyba do^imatrn a ktarou

vztahem!

např. pyo první i*< lnta^Wttoru pouza integrační konatantou

- 129 -

E.

A\ s

» A

'v

>i

0

Prflaa*

j_ Tato chyba • • nonniln* pro-E, J«vi poure pri t i trenu- i

T • •> - ^1*>* f ' ' kr&t&ych ozarovecioh £af*cha v«lfce iaaovi konstantidor.imttru I . Ayamk Jaatll-ie uraiujeae p&rclAlni <5aV-ky, ktere Jsou mali, Janutn^ poiatacni chybu dozl-matru zahrnout do r^poStfl.

Chyba aa projaruja 1 narf«4ila«tt konol osAxanl, t . J . prl ryp-

nuti zar«ni klaaa lidaj o ax-

poalfini ryohloatl porroloaa doBlsctr ho naiitara jako odsaranou dlvicu. Naktari rfroboi. to raSi rypnutim do-slaatru, aby obaluha • *>»ia ibytaina ro»ptyloTina otiskou, proi tidaj doclaatrupo rypnuti i*rl»»ni dal« troohu atouptf. Oritm doslaatr by ukiaal akutaSna oda^ra-aou da>ku, t .J . o tolik rioa, 08 na poSitku ukasorol aana (obr. 2 . 2 ) .

Dalai ohyba, ktarou budaaa naayrat ohybou roajaadu, ranlkd prl rosjagdu rama-

na uryohloyaJa, ktar^ nanaatiri akokaa. Protola raaano aa pohybxija najprra poaa-i a j i a poatupna rrjiuja ryohloat ai na konatantni hodnotu (nakdy a prakmltaa), Ja

Et

taNal"• . • ry«hl**tt

T pof»t«8nloh polohioh dalfcf 8aa a darka ada buda opat napatrna rydSi (obr. S. 3 ) .Nyni si budaaa Tfifmat altuuof, ktar4

v.T;t

vsalkaji r kontrolnich bodaob, Po61» Ori-•a uvadanlho poplau nastane ataV b), raktarea aa vjpini pohyb osafovafa, praa-

»j. noat ovllT&uJa dojecd a rocjetd zdroja

zifeni a star o) , re ktar&a sa Typingzdroj zarani m urychlovaB aa pohybuja kon-

" atantnl ryohloatl. Tjto altuaoa ai nejle-

pa uTadoodaa a niSrtku na obr. 5. 4. Obr.y, 4a a 4b ukacuja atar, kdy Ja nutni saeta-

vlt pohyb idroja cirani, prlSawi pripadb) aa b l lz l ldaalnimu ataru, kdy Ja po-hyb saataran pousa na kratk^ okanSik. Obr.

4o a 4d ukazuji pripad, kdy • • v koatrolnia boda rypini sirani. Protoia aa ala na-Typini docinatr, Ja poiitafini ohyba koapanaorina. Pripad 4d, kdy aa a<rani rypin*na kritk/ okaaiik, a* Ul b l i l i ida<lni»u ataru, ala "a druhtf atrany" nai ja naobr.4b.

Mm a^klada taohto a daliioh tirab, azparlaantd a aarani Java priatouplli ka kon-atrukoi pHatrojfl pro rfaeni pohybor^ tarapia. Jadai at o zarizani drou typfli

Ofcr.3.

130 -

a)

b]

D

C)r

D

d)r

\>

f .

DV

AZ*«unl« l

1. fida'oi • jot An pro riteni spojltrf terapl* v J«dln4m kyruj2. int«llg«ntni rl&loi dozlaatr pro ritnni Jtrokovi tsrttpi*.Karrien^ fidiol ayattfay Is* obtoni prispdsoblt pro Jak^kollr uryohlcrraSa, ariak

T nagioh konlcretniob po<3nlnlc4oh jaou f«i«ny pro pouiiti • im. Kkar«kyml batatro-ny. ftidlci «jst<n pro r£s«ni apojlt< tarapla j« urSan pro bat*tror. B 22 L • aazl-n<itTn< anergif 22 H»V. Vlastnl rli«n£ apojit* pohybor< terapla T Jadtne* kyru j«3r«fieno talc, i» umoifiuj* raallsaol obou algorltafl (obr. 4b a 4d) - aa ziaarc* urjoh-lanya nabo spomalaaya pohybaa, nabo algorltwia na pran^f rypoSat pro kontrolni bod.Potoa or in naxflia pradaa atanorlt, Jmkf prlpad naatana T kontrolnla boda, a taJcaatoaat aaa roshodna, sda "poSki" a pohybaa raa«n« na (Irani nabo m» saxanim, airaaano doaitana potrabatf polofay a prorada korakol pro dalU kontrolni bod. Jfajajan-W lnterral kontrolnish bod* Ja 1°, oo* dar< rrnlkajfof prlblfiani k prttbaka «i»-kor< dlctrlbuoa »ri apojit< pohybor< taxmpil. tfdaja o diroa 1 axpoaloni ryehlaatl

- 131-

jaou př#vtaty t vnitřního dotloatru b<tatronu. Ks b*ta,trcnu jeou nmontovíny ape-

ciální <tní=ače polohy, která polohují r*a#no 1 hlavtoi v iotervalu 1° n tamíř#-

nia na <třed tohoto intervalu - 0,1°. Automat Je reíec Jako úřelový mikropoíit*í

řízeni terapie reellzuje tái verifikační ayatám kontroly oaataveni urychlo-

vače a úlohy admlnlatratlvniho charakteru po ukončení ozáření. Lze říci, íe ře-

Aeni odpovídá aouřaaným poíadavkům a avětovámu atacdardu ne řittni ttr*pl* turyehlc-

V <ouía*E< dob* <a ukončuj* ř*4*ni int<Hg<ntaího řídioiho ůotlm*tru pro ýi**-

ni lírokové t*rapi* pop«m^ v (1). DotiMtr J< urí*n pro Hktrtký b*tatron 19 M*T

a bude a* zitoučtt nt bttttronovjfeh pr*eoviÉtieh v Ch*bu, Chaautovi, po př. T Č.

Budájovloich. Dotimtr cá dva M<la n*táTiala kanály, Ite t^t připojit díi*né

průohotí lonltaíní tcowArícy pro kontrolu <yn*tri* avaztcu tář*ni. Počát*řni chyb*

dotim*tru j< anitatta na tinlnua, protoí* j* pouiito ř*A*ní podlá návrhu Ing. K*-

ráaka a< vatupni dolnofratcvaníni propunti vyMíbo řádu, *soí uno^nllc menňlt ůo-

bu narúatani údaj* o víoa nai jadan ř4d. Calaic j* řaían Jatto příatroj < jadjíodu-

ohyat tpdaobaa ovládAni, napajaoi tdroj- ja pouílt aTta:-ni. Snímaí polohy J# r***m

apaolálná pro batatron 19 MaV, přanoa údaja ja aárlrv^ proudovou tzyčtou ^o tA.

Krok polohy ja zvolán 5° a možnosti přapnuti vnitrní* přapinaíaa ua 10°. řořátak

krokn ja UbovcLný a ja určan naatavaníx ocuřovač* nad paclanta*. Koaaín^ krok

aa naatasruja na panalu a vallíoat úhlového intervalu muaí být níaobk^m valitoatl

kroku. Dotimatr má řadu kontrolníoh ražl^ú. jako ja AUTOTEST a KALIBRACE, a praa-

to ja naotavov&ní a ovládání prováděno pouta a nakolik málo ovládacími prvky,

hlavna diky "inteUganci" příatroja vybudovaného na mikropočítačová tacnnlo*.

Klinická využiti kroková pohybová tarapit bylo realizováno a* radloterapeutlo-

káa odděláni CÓKZ v Chebu. Baham doaavadniho provozu bylo taje otářano táaár 3C0

pacientů, zejmána a onámoenánim moíováho něohýře a proataty. Doatataíni *a tam

mohly ukázat výhody 1 nevýhody kroková tarapla.

Saapomou přadnoatí je apolahlivá díatribuoa dávky v ozařovaná* objaktu, plná

odpovídajioi vypoítanáau ocařovaoimu plánu. Madoohází totiž k nepraanoatl Tliva^

naatabillty úhlová ryohloatl pohybu zdroja mářami a zejmána jaou vylouřtny n*-

přaanoatl zpdaobaná koliaánía dávková ryehloatl báham ozařováni. Dávkovou ryrhlott

na betatronu lz* udriat konatantni jednak použitím omezovač* anebo ručním dcl*3o-

vánim. V obou případech aa jedná o prodloužení otařovaoího čaau a ti* ka aniitni

průchodnoatl pracovUtě. Navíc apolahllvoat, zajmána při ručni atabllttact, j*

velmi diskutabilní. Praanějaí aouhla* akutačná a vypočtená dávková diatríbuo* j *

1 v tom, ía ozařov&cí plán z počítače je počítán vidy jako auma atatietcých poli

a pro plynulý kyv a* apro:imuje. V našem případě lta volit ahodně úhlový intarvtl

jak pro počítač, t*.k 1 pro krok otařovač*.

Snadná ovládání a automatická kontrola eařizaní amUují moimoat vzniku chyby

při konkrátním otíraní pacienta. Poměrně vyaoká apolahllvoat taris*ni (při otára-

ni táměř 9 000 polí byly dvě m*J.á poruohy^ umoínuj* plná klinická vyuMtí b*z

obar z proatoju.

Jadlna nevýhoda a* v průběhu tkouček ukázala při aplikaci na krokovou pohybo-

vou t*rapli avatkao elektronů, kdy ae jadná převážně o homgenni protáření povr-

chu pacienta. V to* připadá ja krok 10° přilia velký. Dokonoa ani úhlový inter-

val 5° není prc větiHnu porrohovýoh lokalizací pouíitalný. Proto j * realizováno

zařizaní umoMujíoí krok 1^ (matodou kontrolníoh bodů). J*diný nadoatatat pcpaa-

ná metody bud* t*dy v n*jkratM dot* odatraněn.

I kdyí a* zmiBnj*** o vyuiití na batatronm, ja nutná znovu zdůraznit, ie vy-

vinutý ayatélm trotavť tarapi* lze pouzYt po uptmvaon na **M*m arychlovaíi, M a

<* uplatní zajmán* v těeh případ*oh. M y nalM zajlatit a doatataínou praanoatí

konstantní dávkovou n*bo uhlovou ryohlozt.

- 132 -

1. J.Ltrhec, F.Bečcar: AutcMtitaoe o)tařeva<CŮ pro pohybovcu terapii, abomít

te ae=in-áře íe. betatrony 82, ZRUT, Karlovy ? M 7 1982.

2. J.uchse: Rol íelověha T ayatewe autoatattuolonnovo nedieinakovo

Movoetl 1*1, ř. 2/1984.

J. J.C-cheo: Automatizace Ktatrond, Aktuality ASŘ Í.2/3.9B3.

QiJALI?Y

w: itA: !Ar!^

<<t<n]'ute «f «^d!atio!t í-oeť<etry. H« Intht4r<te f.4. íregue !),

The treataent of canoer le a aultldlaolplinary effort involving ayoargetie ic-

twractlon of th* ap#eltlltl« of oltnlctl oncoloc pathology, r*diolo^, rAŮle-

<(rM;ny or ultr*<onogr*phy, <ufg#ry. oh<B,cth<rtpy. h<#«atolog-, ta<tm!Olo^y *nú ra-

<3)atio!: tharApy. A tr<*tHtnt protoool i< <!#oíd<d upon following *n *!amlnatlon

ttnč eYaluation o' th< pttlsnt by th# a*d!o*l oncclugy t#M. T h K pntoccl may ba

bmtd on on# or *or< adjuvant ôdalltiaa. tha moat ooamon balag <urg*!T, ohame-

thtrapy tutu radiation. Tha part of traitmat uatn<! račlatlon uwually involva* úa-

ilvary úf a cartain quantity of radiation in aavaral fractlona ovar a parloč of

Hm#. t la tb? duty of the radiation oncology team to maka aura that tha quali-

ty of patleut cara and accuracy of doaa dallvere^ during th* traatmant la the

beat achlavabla undar tha currant atata of tha art.

The taak of traating patianta with radiation la carrlaC out by a taaa dlraetad

h rndjutlou "ncul-tglata. Thla ttaa uaually lnoludaa nuraaa, technologiata, a ťo-

almttriat, a phyalolat and a aarvioa anginaar. Th^ thernpiat In charga of a pa-

tient aonduot* the ataoinatlon, auparvlaaa planning and atllYary of Coaa, a^tchwa

the t rugreaa < f the patient during therapy and effecta any modification of traat—

ment ro^íxe thnt aay be warranted, and at the conclualon of th« rcurae, ravlasn

the efftciency of therapy through foîow-up examinationa. following tha tharaptwt*<

pr-eirlpt!<m r.f a treatment regtna, tha dnaimatriat proca#d# to expl<tra and wor!c

.tt a th*rapy }la« thtst ia optima! for treaMng th^ ;'atleot. Tha treatment plan-

ning. i« flune in o&nattltation with, and undar the general aMparvlalon of the pay—

ň!r)et. After a proper treatment plan la approved by the therapiat, tha doalajat-

rlat detenalnea machine paramatara (a.g. tha axpoaure tlma or aonltor unita, width,

ler.^th and angle of each baa*, aouroa to a U n dlatanoa. Uniting poaitioaa of ro-

tation area etc.) needed by tha teohnologiat to poaitton the patiaat and delivar

radiation doaa. Tha accuracy of the patlant aat-up ia oonfir*ed by tha thax*plat.

doaicetrlat and taohnologlat at tha tl*a of tha firat traatoaat. Taa ounaa and

teohnologlat aaaura ooHfort amd phyaloatl oara during the aat-up and expoww* tv

radiation. The nurwa alao aMty attaad tha patiant during traaafař aad aaaiwt tba

theraplat during aâmination. Tha aarviaaan$%naar h** the Job of a##uring propar

oparation of radiation ejaahinaa and taat aqulpaant* Taa o*llbr*tloa of output and

qustllty of all tha dlfferant radiation baa#j# undar varioua ooaditloaa of u## ia

- 133 -

ieč&ytheynyeícíat.

Quit* číf:*<r<nt <t<ptrn* a!<p< ar* inyolT^d La th* ete-r*\* r#i:T#ry of lytat-

e<ct. *h^y ar*: a)řcowl#íge oř do** yr#<cripHcc; b) předla* urgtt vuûmf i*t*r-

aínatlon; c< tr<at=<ot Línit psrt=*t*r<; ť! sbeorb<Č t!oat c<t<rmÍJi6tlcnj *;

ííetríbuUon *<;L=.atioa{ f! tr**tc<nt pl^sîng^ g) paíítní <*t-upy h'' áo«<

c*tion to pstltnt. ?o aoalev< the í<air# &ccur*oy, ouřU.Hy e.!;:u!-ii3C€ íe rcq

for < H <tep<, b<!t tbs Ttatur* of quality taturatac* i< vary ťífferent for €*.ch o*-

Befor* číaouMtng th< <t#p<, It any bt tKtiMj. tc emm:D* the eomonly <.t:??t€

*rguamt thnt givta ri« to th* :0Dclu<ion that í 5!í McsJrsoy !< ťMíř*bl^ .

!I. AtcurtOT r#dlot^vy^BT

R*di9th*r*ptat< f**iit* th*t !a ora«r to g<t lo- tttaer čoe* r*ourr<ae< rtt*.

th*y h*v# to *ce*);t * o*rt*ia rt<H oř oa<*plto*Hac<. Th# r*^l#t!en tol#rme# of

th* aor**l tl#au* Utaid* th* irrsdiat*d vslum* ^*n*r*Hy lLm!t< th* *b#orb*í úo-

<* th*t eoul4 b* 6*llT*r*d to th* tumor. !a ?lg. 1 aa td*#ltMH r*l*tloa#hlp

/lco*A tumor oontroí and campll-

o*itlOB r*t*w

§M Á /-"-

b*tw**n lootl tumor ooatrol and eomplio*tlan rat* It ahowa. Th* full *hap* of th*

omrr*a for local tumor oontrol and for oompltoatlona la not tmown for any parti-

cular tr*atmant aita and t<ohnlquw, howavar. If tha ourraa hav* any salldlty, lo-

cal tumor oontrol without eomplloattonm pa**aa through a msxlmom aa radiation do-

aalavagrlad.

Doaa-#ffaot ralmtionahlp for tumor loaal control and oomplloatlona ara typical-

ly aiôld In ahapa iaaa Ttg. 1 and 2) aad tha aeourtay raqulrad in th* radlotha-

rapy than dapanda:

?H. 2:Dapandanoa of complication rata

(brmln lnfarotlca nacroal*) on

cumalatad radiatica affaot. (Oa-

tm tatcan from P.Rablm! Ra*l*tlcm

, Tialagy and <adl*tlon Mathology

— . SyllabM. Chicane, *C!t Pa*. 1975).

- 134 - •

- on the ateepneea of the done-affect relationship,

- on the separation between the doae-responae relationship for tumor looal con-

trol and normal tlasu* tolerance.

From ollnion.1 point of view, the oriterla for aooeptable variation in the pres-

cribed dose can be henoe determined by comparison of doae-response curves obtain-

ed for looal tumor oontrol and complication rataa.

Several models have been proposed to define the shape of dose-response curve*.

Ths tiro models gaining the most aooeptanoe are the loglatlo model and the integra-

ted normal (probit) one. Typioal examples of thaae funotlons are shown in Pig. 2,

where logistio and probit curves are superimposed. By the appropriate adjustment

of parameters, the two ourvea can be made to differ by less then 2% ormr their

entire range. This level of different)e is olinioally indistinguishable. For this

study the probit model proposed by Ofcumura at .all'4' and proposed also in ICRU

Rep. No 30 has been ohosen.

The cure and complication rates for human oonoer published previously by nun-

be r of authors were analysed by plotting a probability of oure or oomplloatlon

rate against logarithm of absorbed dose on the probit soale. The slopes of the

ourves of cure rate and oomplloatlon rate were analysed. Let a dose at 50% our*

or oomplloatlon be D_o and Reg, and dose for oure rate whloh is separated by on*

standard deviation from 50% be D and R>( reapeotively. The ooeffioient of varia-

tion, the ratio of ona standard deviation to dose of 50$ our* or coaplioatlon,Vo o r Vr w a r* taken as an lndloator of the slop*. (The values of Ve aad T r as

well as SCQ and R^Q have been established from published data).

The cur* rate and lncideno* of complication are functions of a doe* and varia-

tion coefficients and ar* denoted by C(D) and R(D), respectively. When they ar*

considered to bs sratually independent the oure rat* without complication, P(D),

becomes:

PCD) . C(D) . [ 1-R(D)J (1)

We oonaider that C(D) and R(Dj follow noraial distribution. When a normal distri-

bution with a mean value (± and standard deviation 6* la taken, the integral of

the normal distribution froa negative infinitive to aoaie value x of the variable,

JKx) Is "given byi x

Fix)- J° (1 lofzrr). exp £(,x-fi)2/ 2<tj dx (2)

As the dose is taken in logarithm, and for the oure rate and complicationrate are given byt

<u = log R 5 0 «r= log|Ra- R50|

The theoretioal oure rates without complications war* oaloulatad using eq. (1)

for various sites with the help of derived data from publications. Two examples

are presented in Fig. 3 and Pig. 4. Detailed analysis of curves for our* rat*

without complications has been published elsewhere and therefor* w* give only

conclusion here. Plrstly, the shape of ourves representing our* rat* without oo*»-

plloatlons depends on the doses D_Q and R^o and coefficients of variation T and

Vr| eeoondJly, the ohange of oure rat* without ooaplloatlon with the d*llv*r*d do-

se will be different for different sit** as it is dooumented In table 1, wher*

changes of the probability for our* rat* without ooaplloatloa* ar* fives in d*p*n-

denoe of the change* in absorbed dose of 5, 10 and 15*.

If we proposed that the 10*/ change In probability of our* rat* without ooapll-

oatlon* is olinioally signlfloant, than fro* analysis follawa that the abaorbei

- 1 3 5 -

MM-

tOOi-

*t-

HAMM

*n.my<

*o

ta.o M.O M.0 *0.0

m

Pig. 3.

D^paníanea of oaloulatad ours

rata without ooapllottlon for

aupt^glot^la C# <t# w#ll M ou-

r< ani oompliettion r*t*a on

euamu^L^tsí radiation <ff<at.

(Dat* takán froH H.Hjalm-Haa-

« n , K.J*iK<naaa, A.P.And#r«a,

C.Lunď] Aota Rodiol.Onool. J^,

1979. 395).

fig. 4:

Depena#no# of oaloulat#a our#

rat* without oomplioation for

Ca bladder a< wall aa euya and

oomplioation rataa on ouammla-

t*d radiation #ff#ot. (Dat-\ ta-

k*n fřom R.Morri<ont Clin. {adici,

g^. 1975, 67 and from P. iabin:

Radiation Biology and Radiation

PaUholoty 3yllabua. Chioa*o,

AOR Pwb. 1975).

do<# ahould b# á*lly<r#d, for ntoat aitaa, with total omoartainty battar than-i 5%on the oonfidano* lával of ona atandard da^iřtiou (66%). Thia raeoaaundation waaalraady nada in ICRB Rap. No 2 4 ^ / .

Tor aitaa, whara tha diffamnea batwaaa D-^ and R-- ia larga, tha totjtl wnoar-

talnty oan ba withla ^ 10%, but for aom* <itaa total unoartainty avan battar than

- 136 -

r

L

Tahl* 1

Sit*

Ca urinary bladder

Ca larynx

C« akin aad lip

Supragletic Ca

2*

5%

7*

14%

Dos« ohang* *til6%

7*20*21%40*

±15*

14*43*41*70*

+ 5% is required, which was documented In table 1. It 1B therefore dear that the

requirement for total uncertainty of doe* estimation in photon and electron beams

under physical conditions must be very a!riot, and prescribed quality assurance

procedures must be followed very carefully.

III. Development of quality assurance guidelineBa

The radiation machines used to supply photon and electron beams oommonly used

for treatment of cancer are baeed on variety of physical and technological de-

signs. The performance of a machine is Judged by the degree of consistency of out-

put and consistency of symetry and flatness of the beast. Sine* there are several

different approaches and techniques Involved in this process, a numfcer of profes-

sional bodies have developed numerous working rules for assuring the quality con-

trol. The most prominent of these nongovernmental international organisations are

listed below:

1. International Commission on Radiation Units and Measurements (ICRU)

2. International Cotnmiaslon on Radiation Protection (ICRP)

3. International Eleotrotechnloal Commission (IBC)

4. European Society for Therapeutic Radiology and Onoology (JSSTRO)

5. International Atomlo Energy Agency (IAEA)

6. World Hospital Organization (WHO).

These organizations have Issued several technical publications and oodes of

practice over past three decades. As the knowledge of biologloal effacts of radia-

tion advances, new physical procedures are developed and technologloal Innovations

occur, some of these codes are occasionally updated. (According to our knowled-

ge icnu is now preparing a special report dealing with the alma of quality assu-

rance in radiotherapy "Quality Assurance of External Beam Therapy with Photons

and Electrons" ).

A number of national oodes of praotioe have been published on the base of the-

se recommendations. The health, environment and employed safety agencies of state

and federal governments have, in turn, reoommended most of the praotioal proto-

cols of safety and quality assurance and in some countries enacted them into law.

The first protoool for quality assurance of raedioal accelerator* has been pu-

blished in Czechoslovakia in 1979, whioh was based on the recommendations gives

in ICRU and ICHP reports. A new "Protocol for Cllnioal Doairaetry of Therapeutlo/7/

Photon and Electron Beams in the Range of 10 keV - 50 HeV"' " was introduced in

i;j84. The purpose of this Protocol is to provide the radiological physioists not

only with the accurate method for determination of absorbed dose to watar from

photon and eleotron beams used in radiotherapy, but also with n baaio quality as-

surance procedures. Quality assuranoe programme in this protocol Includes accep-

tance tests of a new radiologioal equipment to ensure that such equipment meets

applicable performance specifications, periodical testa of machines a* wall as

dosemeters at proper intervals of time and basic quality asauranoe procedures for

ensuring a good dosinetry of photon and electron beams. The flow diagram given in

Fig. 5 wea prepared to show each component of the Protoool. The major oomponants

- 137 -

' * ' ' ' ' • ' *

I

• • < " •

1 A i 1 1 *i fti : • "

•. t c ; ' l '

; ; ; ; ; • , ,

wBi i f• r 1 1 r—

ft 1 ! ' iN

. ' . , ' " ! " •

» l l n ' i i -1 1H' 1

I'M

" M i l " " • >

f ig. 5Flow diagram of the Protoool components.

• re llxtod ]n tha neo"nrt 11ns, phyaloal pnromatera or other doalmetrlo <5«t» r»l«-t«d to «acih a.imtiuiiaiit ara ll«tod In th» thlr4 Una and Ihn first Una 1> to »howthat the qunllty aaaurnnoa la rnoaoeary for a«oh step. Detalla o»n ba found In theProtoool Itself or In » P*P«r published reoantly .

IV. Uncartalntlaa In ollnlcal doalmatnr

Eaoh quallttitlva statement of a neasurlng results In radiation do«l»«try shouldountftln at least three figureei

1. tha msaaursd value or tha beat •atlmatlon of tho (juiuitlty to be m»«»ur»dj2. the unoertaln*3T of this value given by a figure, which Indicate a oertaln

range around the meaaured value;3. a figure for the oonfldenoe leyel of this range, i . e . the probability that

the (unknown) oorreot ralue Is embraoed by a given uncertainty range.

The first question whloh la embarrasing la what oonfldence lavel must be usedIn ollnloal doalmetf? ? The estimations of requirements published reoently' ' andresults of analyola performed here were expressed at tha oonfldenoe level of onestandard deviation i . e . 68%. IAEA'"' recommends that uncertainties for calibra-tions of ollnloal do s line try Instruments to be oaloulated on the oonfldenoe levelof 35%. Golten'10' i" using 1.5 of standard deviation, I .e . 85*, oonfldenoe levelfor expression of uiioertalntlea oonneoted with a oomputer treatment pl«nnln< ayw-te». The 95< oonfidenoe levtl has been used here for oaloulatlon of uncertaintiesoonneotsd with ollnioal dosimetrj. A method, whioh Is similar to that publishedby IA£A'9', presented reoently by us ' 1 1 ' has been uaed for estimation. However,there la up to data no general accepted method for combining random and ayatsma-tlo uncertainties to overall uncertainty. The overall uncertainty, U, at oonflden-oe level of 95% oan be written, aeoordlng to our method, as follows:

1.13 (2Sy)2

whar« S_ - a standard deviation of tha mean (rando* uncertainty) and

( 4 )

- eatlma-

- 138 -

t«d maximum poaalbl* error of 1-oomponent (systematic .uncertainty). The equation

la valid for the oe.ee that the estimation of random component was performed on

the base of at least 5 independent measurement*.

An exhaustive analysis of the uncertainties of deliver; of absorbed dose at

a radiation therapy oenter has been performed. The used model was aimed to n-

olude all uncertainties in all the links in the doalmetry chain fro* prime*, la-

boratory to the absorbed dose delivery to a tissue irradiated at a radiation the-

rapy centre. The model was baaed on iontonetrlo doslmetry and proeedurea reoommen-

ded In the Protocol.

Individual errors of each step were analysed and Individual and total uncertain-

ty for eaoh step as well as ouanilated uncertainties were established. Fig. 6 shows

•.t,|iH'.1|<1

[ • " • . . , . . . - .

.' • • '•-.

<

i

•

1

Fig. 6

Mala souroea and va-

lues of uncertainties

In olinloal doslaetry.

\ /-it X

_K

J

the main sources of errors and the individual and oumulated uncertainties at the

confidenos Iev9l of 95*. After recalculation of required values for ollnlcal aoou-

raoy (-5% or ilO5t) at the oonfldenoe level of one standard deviation (68*) to va-

luee at the confidence level of 95* we are getting value* of 10* and 19.5* res-

pectively. Prom the values given In Pig. 6 1* is clear that total uncertainty

for ** Co is under the required values. The value of total uncertainties for elec-

tron and high energy photon beams, which are equal to 13 and 11.5*, respeotlve-

ly, are higher than the required value of 10*. But for most tumor looations the

required value of 19.5* is quite sufficient and for these looations accelerator

beams oan be used without any reetriotlon. From this point of view sites requir-

ing high precision In dooage (for example aupraglottlo oarolnoma) should be trea-

ted on oobalt maohlnee, where one oan garantee better quality aseuranoe.

V. Conclusion

The goal of radiotherapy Is to eradloate a tumor without oaualng sevare dama-

ge to healthy tissue. An overall uncertainty of about -5% at the oonrldence le-

vel of one standard error on the absorbed dose ax any point In the patlaat la

required to meet this goal. When looking Into a long list cf errors whloh say be

enoountered in the aourae of radiotherapy, the raduotlon of the overall unoertaln-

ty to required level appears to be a challenge for the waole tea* of therapists.

physicists, engineers, teohnologiata and technicians. The effort should b« devo-

t«d to the following problem:

1. The overall uncertainty la a oombinatlon of several components. An improve-

ment therefor* necessitates more work In several fields from fundamental dosl-

metry to praotical problems.

2. Direct mistakes In the treatment procedures seam to ba fairly common. There

ere many ways to improve this situation, for instenoe, to apply quality asBuran-

oa programme for all equipment in us* (dosematers, dose planning systems, simu-

lators, accelerators eto.) and oarry out doaa measurements on eaoh patient.

3. Interoomparison of different oentr** Is a Tery useful method to reveal syste-

matic! errors In doalnstry. It la to ba hoped that auoh investigation* should ba

regularly performed even between different oountriee.

4. Regulations and recommendations from authorities or hospital physicist orga-

nizations are of great importance In order to giva minimum requirements on equip-

ment, quality assuranoe programme and oompetenc* of personnel.

To differentiate between the responsibilities of the various members of the ra-

diotherapy team Is not the problem. It la muoh mora important to convince every-

one that a oloaa oooperatlon la absolutely essential in order to aohieve a signi-

fioant deoraaaa of the uncertainties.

Literature

/I/ Wnmberale, A., Deutreil, J., Deutreli, A.x J.Beige Badlol. £2.2-11, 1969.

12/ Weunbersla, A., Ouenlette, J.i Froo. of Sjmp. Advanoee In Dos line try for Fast

Neutrons and Heavy Charged Partlolls for Thorapy. IAEA, AQ-371/1, Vienna 1984.

/3/ ICRU rep. No 24i Determination of Absorbed Dose In a Patient Irradiated by

Beams of I and aamma Rays in Radiotherapy Prooedures. ICRU Pub., Washington 1976.

/4/ Okumura, ¥., Norlmura, T., Olcajlma, S.i Strahleotherapla i22, 109-114, 1983.

/5/ ICRU Rep. Bo 30: QuantitatiTe Conoepts and Doalmetry in R»diology. ICRU

Pub., Washington 1976.

/(,/ Novotny, J., Kovar, Z.\ 5s. radlologla !£, 114-126, 1986.

Ill Protoool for Cllnloal Doalnatiy of Therapeutlo Photon and Elcotron laaaa

In the Ku|* of 10 k*V - 50 HaV. Aktual.klln.onool. 2. 1«!}1, 19B4.

181 LaglnoTi, V., Novota^, J.: Int. Synp. on Radiotherapy In Developlnn Count-

ries - Present Statu* and Future Tr*nd*. IAKA-3M-290/61, Vienna 1986.

/9/ IASl Teoh. Hep. Mo 1651 Calibration of Doeeaeters E/sed In R.dlotharapy.

IASA Pub., Vienna 1979.

110/ Oolten, U.i Mad. Phya. 12, 608-612, 1985.

/ll/ lovotn^, J., Koraf, Z.i 9a. *tand*rdl«a«e i, 237-242, 1980.

- 1 4 0 -

QUALITY ASSORANCN IN RADIATION THERAPY)

IONIZATION CHAMBER CALIBRATION

AND INTERCOMPARISON OF ABSORBED D03Ě3

V. Luginová, B. Pleěko,

Inatitute of Clinical Onoology, Bratislava

J. Novotný, I.Kovář, P. Jirousuk, R. Wagner,

Institut* of Radiation Doaimetry, Cteohoslovak AoademyOf Ccienaes, Prague

s<wm&ry

The secondary standard for calibration of ionltatlon ohambers used in radio-

therapy waa established in 1984 at The Institute of Clinioal Onoology in Bratisla-

va. The neoondary standard oonslsts of Co treatment unit Chisobalt, Baldwin-

Farmer dooameter with Baldwin ionizatlon chamber. Th* exposure and kerm*. rat*a

have been transferred from th* primary doaim*try standard whloh is regularly oheok-

ed. The parameters, uncertainties and atability of the aeoondary standard will be

diooussad.

The intercomparison of absorbed áoa*a from Co gamma rays of therapy unita in

water phantom has boen p*rformed for all radiotherapy centers in Czechoslovakia.

The renulte show*d that all obaarved dosaa war* within ^5% and more than 60% of

absorbed doa*< were within ^3% from stated abnorbed don*.

Jooft patient oara in radiotherapy i* dirootly ralatod to the e^pertlae of th*

inel adniinietoring th* treatment and to the preotaion of the equipment and

tactuiiqueo umed to deliver the radiation done. J'reoision in delivery of radiothe-

rapy servicea ia assured only if the equipment and techniques are checked frequent-

ly and cna,igea indicated by the cheoka ara implemented.

The treatment plan consists of the radiation measurements and calculations ne-

cessary to fulfil the dose prescription. Thers are many steps between the natio-

nal radiation standard and the duration of radiation treatment. The details of

thaae atapa are described in handbooks /I. 2/ or other publicationa /3, 4/. Aocor-

ding tc generally accepted recommendations /5, 6/ and to our own Protocol /7/ th*

reference ionization ohamber should be calibrated in aooredlted aeoondary dosimetry

laboratory. Beoauae there is no central second standard dosimetry laboratory in

Czechoslovakia, the calibration by gamma rays of Co are performed in a primary

doaimetry laboratory situated in the Institute of Radiation Doaimatry of th* Cze-

choslovak Acad'-my of 3ci*no*a in Prague and in an accredited radiotherapy o*nt*r.

Institute of Clinioal Onoology in Bratislava, whioh serves as a seoond standard

dosimetry laboratory for radiotherapy oenters situated mostly in Slovakia. X-r*y

calibration of special lonizatlon chambers are performed at th* Institut* of Hy-

giene and Epi<* mioltgy in Prague, whioh is participating in th* SSDL network orga-

nized by IAEA and WHO, as w*ll as in Institut* of Clinioal Onoology /ICO/.

Hera, a four year a experience with the us* of ssoond standard dosinstry labo-

ratory situated directly in the radiotherapy o*nt*r will be disou*a*d and an im-

pact of ionization chamber calibration on absorbed dos* m**sur*m*nta in radiothe-

rapy centers will be documented as w*ll.

II. Secondary standard

Tha Chiaobalt ^°Co tre*tm*nt unit us*d regularly for th* radiotherapy w*s em-

ployed as a source of gaams, rays for secondary dosimetry standard. Exposure and

- 141 -

kerma rates were established by comparison with the primary dosimetry standardsituated in IRJJ with the help of Victoreen interoomparison 415 ionizatlon chamberand electrometer VJK-4. (The same ionitatlon chamber was used for internationalintercomparison of primary standards). The exposure and kerraa rates were determi-ned for the SSD of 100 om and field size of 25x25 cm2 in SSD 80 cm. Baldwin-Far-mer electrometer, type 2502/3, fitted with Baldwin ionlEatlon chamber, type 2571,has been carefully recalibrated in standardized gamma ray bean and is used a* re-ference dosemeter, i . e . i t Is a part of seo radary dosimetry standard. The consis-tency of secondary dosimetry standard has been regularly ohecked every year bycomparison with the prloary do&lmetry standard using Victoreen lonlsatlon chamber.The oonslstenoy of the secondary dosimetry standard is excellont (see Tab. I) If

Table It Results of periodical cheoks of secondary doslmetry standard in ICO.

Diff. |

1, 000

Sate of measurement I Measured value Calculated value

1.4.1982

1.4.1965

3,869.10"*43,4R9.1O ~4

3.869.10"4

3.465.m"4

2.6O6.1O"4

L. I '} Originally measured value was taken for neit oaloulations.

we talc* ljjto aocount that this unit is used everyday for the patient* treatment.

The uncertainties connected with the determination of exposure or keraa rates and

with estimation of mass calibration factor are summarized in Tab. II and Tab. III.

Table II: Uncertainties of exposure and leers* nates determination of secondary

doslmetry standard.

rSource or uncertainty

uncertainty or estimation of the primary st.

air density correction

air humidity oorreotion

distanoe determination

lnhomngenelty of radiation field

absolute determination of oBarge

estimation of g value and W/e

long tlae stability of VJK-4 electrometer

/J or 3/y

TOTAL UNCERTAINTY AT THE CONFIDENCE LEVEL 95 %

u,2 *0,2 *0,2 *0,1 *0,3 *0,5 *0,2 *

J95" i i , i

Total uncertainty of mass calibration faotor determination In the secondary dosl-

metry standard laboratory was found to be £ 2.4 * at the confldeno* lerel of 95 *,

which is a quite sufficient value for radiation therapy purposes.

III. Calibration

The calibrations and reoallbratlona performed during last four years Included

27 electrometers fitted with totaly 46 loniiation ohaabers. The typea of eleotro-

•eters and lonlcatlen obaabera undergoing calibration are auaaarlaed in Tab. IV.

The calibration procedures lnolude* in all oaaes determination of exposure or

kema calibration factori I.e. the ratio or exposure or kerma to th* eleotroajeter

- 142 -

Table III: Uncertainties of calibration factor estimation in the seoondary dosl-

metry standard.

Souroe of uncertainty

uncertainty of exposure or Icerma rates

air detiaity correction

air humidity correct ion

distance determination

absolute determination of oharge

long time stability of electrometer

lnhomogenelty of radiation field

boam attenuation In the wall

unoertalnt of effectire point of measurement

non-air equlvalenoe of wall material oorreotlon

saturation correction

uncertainty of mass absorption coefficient and

atopplng powers estimation

TOTAL UNCbRTAIBTY AT THE CONFIDENCE LKVEL OF 95 *

or S/y

1,9 *

0,2 *

0.2 %

0,1 *

0,3 *

0,2 *

0,1 *

0,2 *

0,2 *

0,5 *

0,2 *

0,5 *

"95 i 2,4 *

Table IV: Types of calibrated electrometers ani lonizatlon chambers.

r Electrometer

VAJ-18

Kllnlscher Pesisjeter 27012

Viotoreen Radooon 555

PTW - Uiplex

Therados KM I- 2

Baldwin - Farmer 2502/3

IXonizat lon chamber

VAX-1'51, VAK 252VAK 253

PTW 2333^Baldwin - 7 7 1 , BaldwinBaldwin <"'O5

577 i

reading. In some oases also a mass calibration factor has beec calculated usingprocedures described In the Protocol / 7 / . The distribution of founded calibrationfaotors for different loniaatloa chambers and electrometers are documented In Pig.1. Reoalibration of doaemetera produced calibration factors whloh differed not no-

re than — 1 % from previouscalibrations. Calibration fac-tors for Kllnlsche Eoaemeter27 012 fitted with VAK 252.1ionlcation chamber and forBaldwin-Fanner dosemeter f i t -ted with 0.6 om 1onirationchamber were always found tobe around 1.000 ± 0.002 con-trary to VAJ - 18 doseaeters.The highest obserred calibra-tion faetor raluee /O.925 and1.071/ were found for dosesie-

tero without any oheclc souroes or with a souroe belonging to another doseeieter.One dossaster was found during the calibration to be out of order and was reoosaen-ded to repair.

Physicists from the seoondary doslaetry laboratory hare also performed oallbra-

£ s

i

2

t

O.»t 0.83 0.95 0.(7 O.W 1.01 1.03 1.05 1.07

ICQ* FACTOfll

1.0*

- 143-

tion faotor valuaa /O.925 and 1.071/ were found for dosemetera without tmy ohaok

aourcea or with a aouroa belonging to another doaamater. One doeeneter waa found

during the calibration to be out of order and waa reoommended to rapair.

Phyalolata from the aeoondary doaimatry laboratory have alao perfomed oali-

bration of radiation therapy maohinea and doaaaetera in 7 different amall oantera

(5 of them with only X-ray unita and two with Co unita) whioh ahara tha aarvl-

oaa of tha phyaiolata with another hoapital. 3inoa tha quality aaauranoa prooe-

duraa implemented by tha phyaioict muat ba performed on a regular baala, in hla

abaanea tha logloal paraon to oontinua quality aaauranoa oheoka ia tha radiation

tharapy technologlat. Tharafora, thay wara lnatruotad during tha oalibrationa about

tha quality aaauranoa prooedurea on tha apot.

IV. Jntaroomoariaon of ° Co suiita

It waa txpaotad that tha introduction of tha naw Protoool in 1984 and lntro-

duotlon of aaoond atandard doalmatry laboratory in 1982 into radlotharapy praetl-

oa will bring!

1. uniformity in tha ollnloal doaimatry in the whola country;

2. tha imprL/amant of tha quality aaauranoa of olinloal doaimatry prooaduraa

in yadict^arapy aaatar*;

3. poaaibility for objaotiva oompariaon of radiotharapy traatmant raaulta bat-

waan dlffarent oantara.

To taat tha lmpaot of tha !'rotocol on doajaatry in radiotharapy oantara tha

poatal TLD lntaroompariaon of abaorbad doaaa haa baan carriad out by tha Instltu-

ta of Radiation Doaimatry in oooparation with tha Institute of Clinical Onc.logy.

Tha method haa bean deacribad in detail alaawhara /8/. Briefly, alununinophoaph*-

te glaaaaa 3iaos are prepared in IRD and are distributed to radiotherapy centera

by poat. Tha recipienta are requaatad to irradiate the TLD doaemetere to a doae of

i,2 Gy at a depth of 5 om in a water phantom. The doaemeters are returned to tha

IAD and tha abaorbed doae ia determined by oompariaon with irradiated TLD dlaoa

by gamma raya of Co of the primary atandard. Total nncertalnty of the method

haa been evaluated to ba i 3% at tha oonfidenoe level of 35%. ?ha intercom; tri-

aona of tha IRD primary standard with other primary or secondary standards iava

ahown maximua deviation of 0.3%.

Tha reaulta are e:tpreaaad aa tha pereentage deviation between the doaa quoted

by tha radlotharapy oenter and tha dowa maaaured by the IRD. A ^oaitiva deviation

meana that IRD maaauřad dooa ia hlghar than tha quoted dose. Fig. 2 ahowa the per-

oantaga deviation plotted againat

the percentage deviation for all

of the results (25 canters took

part in tha intaroomparison). Tha

dashed ourve in Fig. 2 ahows tha

raaulta of tha interoompariaon car-

ried out in 1975 with tha help of

farroua aulphata dosemeter.

Tha aooeptable deviation for auoh

aimpla doaa maaauramanta in radio-

thanpy la t 5%. All tha meaaur*-

aaata wara found to ba in thia limit,

avaa 60% of maaauramantw wara within

i 3%. Comparing th*a* raanltai with

w M m

t DtVtADOM H ]

- 144 -

lntercomparlson oarried out In 1975 one oan aee an improvement in the do*»ge. Itla worth Mentioning that oenters with easy v i o u i to a secondary standardlaboratory and those making mori frequent calibrations of doaemeters reaohed betterresults. Improvement In dosage i s mainly oaused by Introduction of tba Protocol,by Improved instrumentation and by lmprorement In the quality assurance of tba o i l -nioal doslmetry mostly by mora praclsa calibrations.

V. Conaluslon

Almost flva years experience with the running second standard doslmetry labora-

tory directly In th« radiotherapy oanter shows that:

- the consistency of aecondary standard Is v»ry good, even If the maohlne is

used dally for treatmentj

- the similarity of seoondAry standard and uaars 'beams Is responsible for oo»-

paratlvely small uncertainty whioh oan ba lntroduoed by a transfer of callbratad

dosemeter from one baam to another;

- the Improved doalmetrlo aoouraoy la Influenced by supporting radiotherapy cen-

ters for the creation and distribution of Icnowledga In applied doslmetry;

- the promotion of the compatibility ot method* applied for calibration and per-

formance of doaimetry In order to aohlava uniformity of measurements throughout

the whole country.

VI. Literature

1. H.E.Johns, J.R.Cunningham: The Physios of Kadlology, Ch.Thoa&a Pub., Spring-f ie ld 1983.

2 . Z.Kovar, F.Spumy, Z.Spumy1, J.Novotny, F.Cejnar: Pokroky dozlmetria lon l su-Jiciho zdfoni, Aoademla, Praha 1984.

3 . J.Kovdtnjr, Z.Kovar: Sao. Symposium of Radiologloal Phys ic i s t s , Snolanlca 2 2 . -24.9.1986.

4 . V.Laginova, J.Kovotny: In t . Symp. on Radiotherapy in Developing Countrlaa-Presant Status and Future Trends. IAEA Vienna 1 . - 5.9.1986 IAEA - SM 290/61.

5. ICRU Rep. No 14: Radiation Doslmetry: I-R*ya end Gaama Rays with HuiauaPhoton Energies Between 0.6 and 50 HaV. ICRU Pub., Washington D.C. 1969.

6. ICRU Pub. Bo 35: Radiation Doslmetry: Kleotron Betas with Energies Between1 and 5C MeV, ICRU Pub., Betheada 1984.

7. Protocol for Cllnioal Doslnatry of Therapeutic Photon and Eleotron Baaaa Inthe Energy range of 10 IteV - 50 HeT, Aktual. k i l n , onkol. 9, Bratis lava, 1984.

8 . -a.Wagner, J.RoTotni, P.Jlrouiek, I.Korar, I.Horakor4: Raa. Rap. Ho 0SZ1S5/86, Traha 1986.

BESTPJtHLUHSSRAOM PUR GAMA-HEUTROKEH BRACHYTERAPI8KIT Vc3l yjKLII) CALIPORHIUM-252ID VUKEO 3RMO

V.KryStof, T.Ta£ar, O.Ott,PorschuDglns t l tu t f a r Ic l inlache und axper loanta la Onkol o g l e ,Brno, i l u t y kopao 7, 533R

lloderna £&twlcldung der Brachytarapia der bBsart lgen Heubildungen i a t gekennre ioh-ne t duroh d i e Einftthrung dar Quella ^ Cf sur Hellung von e i n l g e n gawanlten Tuaiorlo-k a l l a a t l o n a n . Das Intaraasa ua dla Auanutmung dar gaaa-neutronen Stratalunc i*m l a o -

- 145-

topa daa '.i8. Eltmentea daa parlodlaohan Syatataa von Mendelajev, walohaa in Jtthra

1950 von 'j.Jaaborg Oruppa antdaokt wurda, lat an dia Badlngun<; gaknupft, d*ea * Cf

im VarRl'lch mlt ajideren Hadionuklidan boha apatiflaoha Hnlaion von ř.autronen hat,

walohor w#rt -^.lOâ'^.t"^ batrágt. M.a Einfuhrung dar gtma-neutronen ÍJuolla ^^ Cf

in die Mrttohytarapie kCnntan wir batra.ohtan ala ainan nauan kvalltatlvan Zutrltt

tur Auanutzung dar oharaktariatlaohan fy«l)c<li<oh*n und radiobiologlachtn Klgtc-

aoh*ft<n <!<r Keutron<n tur H*ilung d<r bB<trtig*n N*ubildung<n alt hBhtrtB ImhAlt

d*r hypoTtl<ch<n Z<ll*n.

Dia Quell* ** Cf atrahlt *tw* 60% N<utron#n und 40% Photentn <-m. Ll< Mlttalwn-

argi* dar Nautronan lat ln Gransan 2,10-2,37 MaV und dla Gaa*atr<thlung 1 MaT. Ha,lb-

taUttarfnl]. T. ,y lat ^,6^1 Jtthra. Ala 3trahlanf;ťalla mlt dar Kompnânta. dla duroh

dan hohan linoaran KjtargiatrtLnaport gakanntalohnat. lat, h*t di* ^ Cf hBhara radle-

blologlaoha Wiritung in Varglaiob tu dar GamMtrahlung.

Hoha mdioblologlacha WlrkHMtkalt dar Kautronankonponanta dar Strahlung voc

^^Cf fnrd«rt dáti banondaran radiohy^laníaohan Hagima bal Varbrauoh dlaaar ,uallan

tur Apllkation in rndlottrapautiaohan Abtailuftgan vor «liaa vott ut*ndtptMt)(t <tua

dar Ulchan.mg daa ^chutzaa und dar íSlohrrhalt dar Arbalt daa !'araona.la. t la trfor—

darllohon rAdíohy^laniaehan BadlngsmgHn fCr dan ttllnlaohan Batrlab mit dar <,ualla

Cf, aind mBglloh nur auf hooh apa<l*lialartan Abtallungan, dia mit apaclallen

Einrlohtungan fQr dan LaârrauD: Manipulation und Sohutt daa Paraonala vor dar K*-

ma-und nautronan Strahljng, dla aoitnalla, pr^zlaa und ainfaoha Manipulation mlt

Kautroforan HrmBgltchen aind a,u#âatattat.

Soloha Elnrlohtungen far dla !<*garung, Manipulation und Sohutt daa J'araona.la'5?vor der gatna-meutronen Stra^lung von Cf, mit gaelgnatan Manipulatoran und cit

Bliok auf dla Wirklichkalt, daaB dla Aumuttung daa Nukllda * ^ Cf PomRne dar fHh-

randen radioterapautischan Abtailungan in UdSSR, USA und Japan lat, alnd tur Zalt

lm Produktionaprogramm keinar Waltfirma. Ba iat varstRndlioh, daaa bel des Emu daa

araten taehechoslowaMachen Arbeitaplattaa f&r dle gama-nautronan Braôhyt^rapla mlt

** Cf in dem řorachungainatitut fHr klinlaeha und #Tparimantala Onkologla in Brno

dla Probléme, dla mlt dam Batriab daa Arbaltaplttsea verbunden alnd, gans bahtibra-

ohand tu 18a*n nBtlg war.

H a Auai!tatung und dla Anordnung daa von una gabautan Arbeltaplattaa fQr intr*-

knvitHra Brmohyterapla bal Auanuttung der Quallen dar gamtna-nautronan Strahlung

Cf iat aua dar Vorausaettung auagagangen dia Bedingungan fHr optimala Arbai^t-

organiaation im Lqufa dar Manipulation, EinfHhrung und Batrautmg der Kranken mit

eingeftMirten Quellan mlt dar gleiohzaitlgen Sicharhait daa Peraonala tu achaffan.

Mlt RBokaicht auf dia hoha biologiaoňa Wirkaamkeit dar Neutronenatrahlung von ^ Cf

war aa nCtlg den Arbeitaplata ao aitularan, daa* tu kainer ErhBhung daa R*dl*tlon*-

hlmtargťundaa tn dar !A<#<bHn#, dl* fWr dta Offantllohkalt snajínglích 1**. !co<«aw

konnta.

In dar radloterapautiaohtn Abtellung unaaraa Inatltuta konmtam wir aoloha Ford#r-

ungan zu aichem im Erdgaaohowa daa GabKudaa, im Raum, dar nur ÍWr dia Apllka-tlon

dar Qualla ^^^Cf mit dam Systam Aftarloading und ftbr dla Lagarung daa ?atlantan

mit aingefnhrtar Qualla dlanta.Mntar tmdaram dlant diastr Ra,um ňtr dla Ltgarung

und Manipulation mit dan Quellan. Dar Haum lat mlt dam apaziallan Traaor fBr dla

Lagarung dar Quallan ^^Cf und dla Vorbartitung álay Nautroforan fRr dia

und mlt bawagllohan Sohirman f&r dan 3ohuta der Rytta vor Hautronan

Dar Oaaamtanbllok la dan Ra,um zalgt dia Abblldung Numaar 1.

- 146 -

Abstract

252-CAMFC'RKIUt5 TREATffiEIiT ROOKIK RlCiO 3KK0

At last year the specialized treat-ment room was built in R1CEO Bmo. The-re ere sources on the baals of rodiomic-lide ^52-Cf used for intracevitary eppli-cetiona by gynaecological tumors espe-cial ly . U.S.S.R. is the producer ofour i52-Cf sources. The workplace ari-ses during the cooperation with someInstitutes and factories of town Brno.Some parts of the treatment room arethe oubject of patent proceedings underthe stand of Chirane Research Instituteof Health Technology. The workplace In-cludes parts for safekeeping and hand-ling of sources and personnel protec-tion against gamma-neutron 252-Cf ra-diation.

PROTQH THERAPY

WITH THREE PROCEDURE ROOMS

I.V.Chuvl lo , L.L.Goldin, V.S.Khoroshkov, S . I . S l o k h i n ,V.M.Brejev, I .A.Vorontsov, J .L.Kleinbock, S . P . L i s o v e t s ,lTF.Lomanov, L.k'.Pavlonaky, O.P.Fedotov, G.G.Shimchuk,

Institute for Theoretical nd Experimental Physics,

Atomic State Committee of the USSR, Moscow

V.J.lledred,

Institute for High Energy Physics, Atomic State Coamlttee

of the USSR, SorpoukhoT

V.V.Jermolaer,

"Tensor" works, Atonic State Conmitte* of the USSR, Dubna

Radiation therapy by ••an» of proton beaos or other Heavy Charged Particles

(HCP) is carried out or is planned to be realized in the next future at about ten

centres in the world. Three of thea are created in the Soriet Union, namely in Dub-

na (1), itosco* and Leningrad (2).

^ore than 6000 patients with different diseases bare been treated by HCF beans

in the whole world. At tfae end of the sixties, when this work was started in the

USSR, foreign scientists had accumulated a certain experience In small intracra-

nial structure irradiation*. Irradiation of cew growth* localized in other part

of huoan body were carried out Is ssjall cusiber of eases.

- 147 -

J?roe the very beginning proton b»uD« have been considered by Soviet cliniciansas an instrument for self-dependent or combinative irradiations of oe« growthsand structures having different dimensions and localized In different parts of thebody (3 ,4) . This conception defines the development of cl inical «crt at the 70-200KeV proton beam of Institute for Theoretloal and Experimental 1'hyelcs (JT£?) syn-ohrotron for about twenty years. Proton Irradiations are here carried bj 6 -ynberof Moscow leading cl inical oentree *(5). 1270 patients received about 15C protontreatment courses from 1969 to 1906 beginning (see Table 1) . At the s u e l«e tech-niques employed for irradiation of targets hoTlng different shape, volume itnd lo -oallzatlon, as woli as the equlpnent for dose f ield forming and dese f ie ld measu-ring, etands for patient positioning and shifting Irradiation, oheoklng and con-trol devloes hare been developed and improved. At f irst the work was oarrted outIn one prooedure room equipped with devices for tntraoranlal targets and eye tu-

Table 1: Radlotrsatment at the ITEP synchrotron proton beoa

rear/No

f~ 1969T97"0

! 1971 "!" 1972

1975l'j (O

;~ 1977, 1978

1979r~"l980

198119821983198419851986

Totalnumber

1

46

17

2

62229301010"151424

8973

1321

221

3

191

I 302522~115

33

20

711

62

164

2

122 6 "494X^52 J

1134520

360

-i138

1

4

2

1

47

6

8

111921

193028

27

15

1821

r7

1

32620)2

26

40

28

17

219

B

-

-

11017266

60

1" '

9

. 11 J49 j

63 111 J42 1

529296

114114130222

15460

1250

1 - support loooaotor systea^ 2 - sexual sphere tumour; 3 - pituitary gland withdlsharmonal malignant tumoursj 4 - combinative (p + gamma) Irradiation of pi tui ta-ry gland and metastaaea with masunarj gland oanoer; 5 - akin melanoma and metasta-sesj 6 - sight organ malignant tumours< 7 - pituitary gland adonoaa; r, - vesselpathology of oentral nervoua systeai 9 - total number of patients.

• All-Union Onoologlo Solentlfio Centre, Aoadeay or Hedloal Scienoe of ths USSRjHelmhola Solsntlflo Research Institute for 87a Diseases, Ministry of PublleHealth of the RSf3R| Sourdanks Solentlflo Research Institute for Heurosurgery,AMS of ths U3SH Ssientlf lo Researoh Institute for fedoorlnology and HomoaaChemlstrj, AMS cf the USSE| Scientific Researoh Institute for Urolofj, MFH oftba RSKR.

- 148 -

mours irradiation (first device), a^d for urogynaecoiogical tumoura irradiation

(aecond devioe).

In order to realize new radiotreatment teohniquea *ad to increase the faoillty

capacity (ntjmber of radiation sessions per day) additional procedure rooms were

required fir specialized equipment aooomodation. Ereotion of m building with three

prooodure rooms (fig. 1) was oompleted in 1980.

Plan of the oomplei with three prooedure

rooaa:

TM - bending magneta;

PR - procedure rooasg

CR - oontrol rooms;

PP - patient preparing room.

Irradiation in the procedure roonn are oarried out by tuma. The beam with a

proper energy for e*oh irradiation aeasion is kicked out from the accelerator or-

bit and transported through the vaouun chamber to one of the procedure rooms (Pig.

2). The b**an in e*oh procedure room art horizontal and their axaa are fijed at

about 1.5 m height above the floor. The proton beam in extracted from the accele-

Fig. ^:

Piagram of proton

beam transporting

channels:

KS - kicker aeotionsj

ÍM - deflecting mag-

neta;

TM - bending magneta;

C - magnetic direo-

tion correctora;

L - quadrupole len-

aena;

PR - procedure rooms.

rator in a form of ahort pulaes with about 100 na duration and 0.3 Hz pulae repe-

tition frequency. The beam intensity ia KT' - 10^ paftiole* per pulae.

Therapeutic doae is gathered in a fraction of a aecond in oaae of one-field irra-

diation. In shifting irradiations doae accumulation time ia determined by the ve-

locity of patient diaplaoement with reopeot to the beam and inoraaaea up to 30 min.

Patient positioning laata from 2-3 to 30 min. In complicated clinical oases a

rehearsal positioning is to be oarried out one-two days before the irradiation.

It ia neoeasary to mention an important feature of the work organization at the

ITEP accelerator proton beam. Mot more than 8% of partiolea aooelerated up to ths

neoeaaary energy ia taken from the synohrotron orbit for medioal purposes. The re-

maining beam ia going on accelerating for use in phyaioal experiments. Th*a opti-

mal oonditiona for olinioal work and attendant doaimetrio and radloblologlo*! ex-

periments are created. Such work can be oarrted out every day sismltsnsoualy with

- 149 -

research In high energy physios during the whole accelerator working time. The ao-

oel«rator works five one-and-a-half month cycles a year with four fortnight inter-

vals and one two-month summer stop.

Three specialized irradiation devices (stands) are functioning now in two pro-

oedur» rooms. A stand for intraoranial target irradiations ia looated in one of

the prooedure rooms. The patient Is plao»<i in a lying position (Fig. 3). The posai-

Fig. 3:

First procedure room equipment (stand

for lntracrar.ial target irradiation):

Jjegr«es of freedom for equipment ele-

ments are shown by arrows.

1-rotative table, .?-disk for patient po-

sitioning, 3-b«ad supporting platform

with a headholder, 4-tuming devioe, 5-

colllmator, 6,7-slde view lntroscopio

oentrator (a oouple of an X-ray tube and

•leotrooptloal transducer), 8,9-frontal

view intro»copi06il centrator, 10-stereo-

taxlo pole.

bility of bringing the beam praotioally from any aide of pntlent'e hpad is an im-

portant feature of the devioe. The single shadowing part of rotation mechanism at

the will of the operator oan be put In a position, whioh leavos both sincipital

and temporal parts of the skull open for the beam entrance. :;uoh stand transfor-

mation takes one-two minutes and does not alter other conditions of the equipment

functioning. In oontrast to the analogous stand of first generation hpre it was

managed to place in a fixed position two pairs of lntroscoping oentrators (JC-ray

tube and eleotrooptioal transducer). That made it possible to avoid moving them

forward and adjusting before irradiation*. It increases the patient's positioning

accuraoy and reliability and shortens the total irradiation session time. In addi-

tion the stand is equipped with light oentratore simulating the proton beam and

the introscoping oentrator axes.

Possible stasd element displacements are shown by arrows (see Fig. 3). The stand

provides rotation of the lying patient around the vertloal axis and its head tur-

ning around the horltontal axis (body vertebral axis). The point of intersection

of their axe* (the NO oalled rotation pole) Is fixed In tht apao« biting brought

in line with the beam axla. The Intraoranial target to be Irradiated is brought

to the same pclnt.

The patient"« head is fixed by an Individual ihennoplRstlo mask stiffly faste-

ned to the head supporting platform. The target la matched with the rotntlon pole

by means of lntrooouplnK and light oentratora. for the purpo«e the hem1 supporting

platform is able to move in three mutually perpendioular dlraotlunn. Iiaplaoement

range and discretion are presented In Table 2.

The second procedure room is equipped with a therapeutic stool Intended for

irradiation of targets looated in the thorax. In the head and neok, and in aye tar-

geta. The layout of the stand la presented In rig. 4. ratlent fixation 1n H »ittlnj

pooitluu, rotation around a. fixed vartloal axis Jntarseating th« beam n*i», and

+ Centrator displacements presented In Fig. 3 (h, 1, J, m) are neoeset.ry only when

adjusting the equipment (not the patient).

- 150 -

Table 2: Intraoranial irradiation atand displacements

I—Movementdirection

a ,d , i Z

b , e , ± Xy + y

U a r o u n d Y

Range

i 70 mm

i 70 ram

i 85 mm

i 126 degrees

Ldsoretion

0 .

0 .

0 .

1

1 mm

1 mm

1 mmdecree

1 around I £ 36 degrees I 1 degree

Pig. 4

Second procedure room equipment

(stand for thoraa, neok, head,

eye and orbit target Irradiation):

Degrees of freedom for equipment

elements are shown by arrows.

1-rotatlve stool, ^,3-colllma-

tor turning device, 4-ceillng

beam, 6-eye and orbit irradia-

tion devloe, 7-head support,

8,9,1j-introacoplc oentrator

la couple of an X-ray tube and

electrooptlcal transduoer).

linear displacements In three nutualjy perpendicular direotions are provided.

•hen eye and orbit targets are irradiated, the head of the sitting patient ie

fixed by an individual raask in a special device. In more simple canes The patient

is fixed without mnsk. The device provides the same angular and linear displace-

ments as thn stool. The possibility of foroed turn of the head around the horizon-

tal (His intersected with the beam ails, and vertloal rotation ails In provided

besides. The target to be irradiated la matched with this point of three aiea in-

tersection. The aeoond procedure room la also equipped with the ir.troHcoping cen-

trator and a multibeam laser light centrator, developed by the Central I«slgn Of-

fice, Academy of Medical Science of the USSR, i'ossible displacement range and dis-

cretion of the second procedure room equipment is presented in Table 3.

A radiotreatment stand for Irradiation of targets located in urogynaecologic

Bph«rs of patients In lying and standing position la f.t present in assembly in the

third procedure room.

Speaking about the doa» field forming It la neoessary to note that from th«

acoelerator are extracted protona with some fixed energy values. &iergy and a cor-

responding range of coming proton beam are to be chosen more precisely by changing

the thickness ( but npt more than 4 «.«• ) of the degrader located before theirradiated objeot. Depth dose distribution Is formed by a ridge f i l ter and bolu*

compensating the surfaoe ourvature at the beam entranoe. Dose distribution forming

in the transverse oross-aectlon is aooompliahed by a thin soatterer which Improvesthe dose distribution uniformity, and by oollinators. The general tendenoy In for-

ming system development is not the seleotion froa an available dose field set, asIt h*» been up to the present, but the oreatlon of Individual dose fields for each

- 151 -

Table 3: Displacements of the stand for thorax, neotc, eye and orbit targets

Irradiation.

Movement

dlreotion {

+

around y

around x

• ±xb t t

around y

T " •"• rRang*

± 80 urn

± 50 DB

± 75 mm

±180 grad

± 30 grad

±250 am

±250 mm

±800 mm

±180 grad

Dieoretlon j

C.I mm |

0.1 mm

0.1 on

30 mln

30 mln

0^5 mm

0.5 mn

1 .0 mm

1 grad

separate clinic caae.

Dose distribution and doge measuring beoomes oomplloated due to hlp,h synchro-

tron beam pulse pow»r. 10 - 10 partloles pass through the target In a 10C ns

psrlad. That corresponds to 10 - 10 Gy.s pulse dose rate. Monitoring of such

Intensity beam by means of ionlaation ohambers seems to be dlffloult. tnduotive

probes (current transformers) measuring proton flux are used as monitors In Irra-

diations (6). Speoiolly developed pulse ionlzatlon chambers with small volume and

gap serves for depth dose distribution measuring and model (phantom) research (7).

Transversal dose distributions are investigated by the photographic film technique

(8). In dose distribution investigations photolumlnesoent deteotors are used as

well (9). Adaptation of commercial autoaatlo system with semiconductor deteotors

to high pulse Intensity proton beam Is to be nearly completed (10).

Absolute dose calibration ie carried out by the induced activity method in *2C

(p,pn) l^c reaotlon. Inrormatlon in translated from analogue into digital torn,

prooessed and lndloated by systems working on line with the computer, when nil

enumerated rfooiraotry methods are used.

The accuracy of our doslmetrlo measurements cun be estimated as follows: abso-

lute nose calibration and dose delivery - - B%, dose dlotrlbutlon ntaourlng no u-

raoy - 0.5 - 1 mm.

The oomplex with three prooedure rooms is controlled in a large measure by a

computer. One can aar< out same looal sub-systems controlled by a computer. Three

microcomputers MKRA/60 are controlling the equipment looated in the procedure rooms

as well as beam extracting and transport devloes. A sub-system for patient registra-

tion and accompanement and a sub-system for processing doslmetrlc film Information

•re realised on minicomputer SII-3 bass. Rndlotreatment plenning and optimisation

system is ualng the minicomputer 3M-4. Oonsolldatlon ot looal oontrol aub-nyateas

Is a general automatlo system, for the whole oomplex will be aooompllshed with-

in next two-three years. That will anlargs the automation possibilities of physi-

cal and doslmetrloal investigations, as well as preellnloal and cllnioal procedu-

re automation. Considerable reserve enlarging of eaoh separate oontrol ohannel

shall be an especially important result of the general automation system oommlsslon-

ing.

In conclusion authors would like to acknowledge olinlolsts A.P.Brovlclna, O.D.

Zarubey, V.H.Xlseleva, L.E.Klrpat.ovskaya, V.A.Krymslcy, Q.V.MckaroTa, E.l.Hinako-

va, E.I.Unrova, A.I.Ruderman, V.O.Khaeanov, E.V.Ehaelevslcy, E.V.3huv«lov who pro-

duo ed and prooessed a summary of radlotreatraent oourses whioh they oarrled out

at the ITEP proton synohrotron.

- 1 5 2 -

Abetract

A number of Moscow medjoal oentera have oarried out proton radiation therapy

for patients with different types of diseases ainoe 1969. ITEF synchrotron troton

beam with the energy up to 200 MeV has been used for the irradiations. These lrr*-

diationa employing a speoial eTtraoted proton beam have bean put into everyday ro-

utine pr*ctloe in parallel with the physical research performed at the synchrotron.

Two more channels as well as two prooedure rooms have been operated sinoe I?fl2.

A spaoial set up of equipment, inoluding ollnioal doaimetry tools, patient irradi-

ation equipment (four speoial units) and computer-controlled systems are now In-

stalled at the faoillty. By present more then 1^00 patients have been irradiated.

Thia report presents a desoription of physical and dosimetry equipment and techni-

ques of irradiations. A summary table containing data about patients and rlinical

resultn in also produced.

References

1. V.r.Lželepov, L'.V.Savrenko, B.V.Astrachan i dr.:"Mnogoicabinnyj Kompleke la-

boratoriji Jademyoh problem GIJAI día iapolzovanija ťaželych zariařer.rtych ctstlo",

Trudy řervogo Mexdunarodnogo seminara, Moakva, 6-11 dekabria, 1977, vypusk I, atr.

43-49-

<?. B.V.r.ounov, U.L.Karlin, V.B.Nizkovolos i dr.: "FiziXo-tachničeskij kompleks

protonnoj terapii na 10(<i' MeV na slnohrooiKlotrone LIJAF, tarn Xe, str.sO-55.

3. Abaxnv, V.I..Astrakhan, B.V., Blokhln, S.I., et al: "Use of !roton B'MS

in the U;; ii fcr Medloul and Blologloal Purposes", JINR, E-5H54, L<t!br.a, 1971.

4. L.L.sioi'din, M.F.Lotnanov, V.3.Choro&nov: "Frimenanije prcttmnych pv-řkuv v

mpdlclne (opyt ITEF), sbomlic "Problémy jadernoj fiziki i fiziki plementamych

Saatio" (Paniati A.I.Aliohaj^ova), Nauka, Moa-tva 1975, atr. 2EO-3O1.

5. Chuvilu, I.V., Goldin, L.L., Khoroshkov, V.3., et al: "ITEr Synchrotron

Prcton Bean: in hadjotherapy". Proceedings of the International Conference on Appli-

cations of Hiycics to Medicine aj.d Biology, Truest, Italy, 3t- March - 3 ril,

190<!, Aorld Jcientifio, ^.p. 45-67.

<<. f.lo,}t.ijnK, J.L., '.arinakij, V.M.: "Slsteme. opcratlvnogo irmerenija intenaiv—

noatl n<-(<.tKo-biolo%lf*Hifon') r^^tonnon^ pu^ka", "Atdmri'tja t-nergija", 37, N.7. 1''74,

str. ř.''-70.

7. ;.ia«vec, J.i'., lAikjaňin, V.J., 3lmřuk, 0.0.: ionitaciorttiaja kamera v impul-snyah p^.xach prutonov s vyaokoj moňřnosťju do?y. Tezlsy dokladoT. VII.

noje aov*ořanij9 po dozlmetrli lntenslvnyoh potckov lonizirujuáUch lzlučenlj,

ubninaK 1'.'83, etr. 14^-143.

8. <\osťuřenko, V.I., Hsovao, S.P., Qrut, E.A., Kaplun, L.J.: řotodozimetr

uskorenj^yoh protonoT "Pribory i. technika. *ksp#riments.", 1904, N.2, str. S3.

9. Kosťuřsnico, V.I., Choroakov, V.3.: Fotolumisoentnyje detetctory ID-11 v po-

lach protonnogo izluienija-. Teelsy doicl^dov. VII Vsesojuznoje awvtšíanije po do-

zimetril intennivLjoh potokov ionizirujuěčieh izlučenij, Obnlnwk 1983, atr. 147.

10. Pitner, G., Grusell, E., Lukjaahin, V., LomMiov, M., Kostuohenko, V.: Ra-

diatl -n damage <md doae rate linearity response of a P-Si dtteotor in 70 MeV pro-

tons, "Nuclear Instruments and Metbods"v.217, n.3, p.501, 1983.

- 1 5 3 -

BSPECIAL TOFOMETRIC AND DOSIMETMC FEATURES

O? DIFFERENT PROTON IRRADIATION TECHNIQUES

V.S.Khoroahkov, E.V.Beljaikin, V.M.Bre^v, V.I.Koatjuohanko,

S.P.Liaoveta, M.F.LomanoVt V.P.Pohvata, Q.G.Shimohuc):,

V.A.Krymakly +

Institute for Theoretioal and Experimental Phyaiaa,

Atomio State Committee of the USSR

+ Bourdenko Scientific Raaearoh Institute for Nemroaurgery,

Academy of Medioal Soienoe of the USSR

There are two taohnlquez employed for proton irradiation - to pace a proton

beam through a target (through irradiation) or to atop it in it (beam atop irra-

diation). The benefit of tha first taohniquw ia A very amall angular divergence

of the beam penetrating tiaauea and, consequently, a very high lateral edge field

gradient. Tha aecond one haa two additional advantages - the abaence of radiation

leaiona behind the target and the increase of thu stopping power (dose) at the end

of tha beam range looalized in the target.

When comparatively amall targeta are through J.rraóiaíed (croaa-fired) the rela-

tion of the aurfaoe doae to the doae at tha t&rgitt ia nearly equal to the relation

of tha target oroaa-teotlon to the integral area of the fields at the beam entrtn-

ol* The doae at the tieauea on the beam patn gradually inoreaaejaa approaching to

the target (Pig. 1 ) .

Fig. It Doee diatribution in pituitary gland through Irradiation.

Th* tJtltťttpal [tarametara in through irradiation planning apet

target deatruwtlon doaei

volume of the body portion through whioh the b#am can be guided to the target^

integral area of poaeible entrance field*;

tolerance (level cf permlaalble doae) of tiaeuoa along the beam path.

So fay *a the value* of the aeoond and third parameters are limited by the an*-

tomio atruoturet It la olear that a deatructlve doae can not be obtained by through

irradiation withim the limita of tolerance for tlnauea poaltioned along the beam

way to the target.

In thla caaa one muat uae another teohnique whnre all the partiolea are atopped

In the t*rgat. The inoream^ of the lonisation energy loaa near the position of the

beta atop (Br*gg paeJt) maJcea it poaalble to inoreaae aeverml tiaea the relation-

10 -

50 -

40 •

JO -

20 -

It -

0 —

<0

uMiO <m

JO -

6 0 -

- 154 -

•hip between the target doae and the dose ln tissues along the way to the target,

aa well as to the akin doae.

Thus the ohoioe of the irradiation teohnlqu* Is in a great measure determined

by target dimension. Whan larger and larger target* are to be Irradiated one comes

to the point when the use of the beam atop .technique beoomee Inevitable. Aooor-

dlng to the lntraoranlcl Irradiation iizperlonoa it la advisable to use the bean

atop teohnlqu'e irradiating targe<a with roliuaea exoeedlng 4-5 oom. Dealing with

voluaea oontlguous to the mentioned on* muet bear ln mind a following oonaldera-

tlon. The tranaveraal (with reopeot to the beam) dose gradient at the target bor-

der la always superior ln through Irradiations beoeuae the effeot of angular par-

tlole aoatterlng la not ao strong at the middle of the partiole range, as at the

point of its atop (fig. 2). i» a o m« ejiatomio altuatlona thla consideration may

y \A \t,

H l

fig. 2i

Longitudinal doae diatrlbution in the bean with 60 am diameter and 180 HaV energy.

Tranareraal doaa gradient ln A-A aeotlon la muob higher than ln 3-B one.

Se a deolalTe one when ohooalng the Irradiation technique. The through Irradia-

tion oan be ohooaen e/en ln oaae of oomparatlrtlj large targets irradiation.

The aeoond teohnlque - Irradiation with bean atop in the target - la alwaye

more oomplloated than the flrat one. Htre it la Tery Important to keep atriotly

to the predetermined poaltlon of the Bragg ouire (or the longitudinal doae distri-

bution - modified Bragg outre) ln the target. Hoat important la the proper poal-

tlonlng of the final portion of the ourre (part AB, fig. 3) whioh aooordlng to

M g . 3i

Longitudinal doaa diatrl-

bution matched with the

target.

Ctr>

the prooedure plan muat be preolaely looatad la bordera na ot the target. The

teak la eepeolally dlffloult ln the oaae of heterogeneous objeot lrradlatlona aa

far as the beam passes several media with different densities <j> g.asi""5' before

it reaohes the target.

- 155-

Two information maaaifa are at olinlclat a tmd phyoiaiat a diapoaal for irra-

diation planning. Tha flrat ona la a aat of longitudinal doa* diatributlona*

(a.< it la ahown In Tig. 4) obtained experimentally in irradiation of a homoganeoua

Longitudinal doaa diatributlon ob-

tained by tha homogeneoua phantom

experimental irradiation.

^ dE/MeV.om^jphantom, whoae denalty p (g.om*^) and aptolflo energy loaaea — f — — ! ara

' dx \ g /

nearly equal to thoaa of aoft tiaau*. Energy loaaea M a referad to tha aoe pted

in nuolear phyaioa langth unit I whloh ia Mprasead as(g.om" ) i.#. prodtn .Ian

of media danalty ^nd lta langth (om). Tha aaaond information maaalf la a

matrlo pattam of tha invaatigat*4 body aaotion or aaotlona (?lg. 5). *

T^fZ*.

Z^/

rig. 5: TopocMtrio aaotion diagram of tha Irradiated ob

Th* ohoioa of dtxe di*trlbutlon for «toh irradiation <!!r#otlon i< of a great

imortanoe In r*<1lt)tr**tm*nt ulannlng. It muat aatltfy following oonditlona (ia

tarma acoepted in ?ig. 4 and 5)'

i(doaa max.) - P . x 1 . (1)

Ktotal) (2)

Two poeoibla error aourota in beam atop lrradiatlona are aeen in the aboye fcr-

xu!ae< «r<'m eatim-Hon of media extent 1, and their den«!ty (' .. !\!e to thl«

errora th# 1 ngltudlnal doea diatributlon curve and lta portion AB (y!g. s) at the

target region, what la of eapeoially great iaportanoe in radiotherapy, ere dla-

plaoed. That reaulta in undarlrradiation of a part of the target, or overirradla-

tion of tiaauea and atruoturea ajaoent to it.

Irradiation teohnlqua with proton beam atopped in the target can be worked out

on the baaa of a method of quantitative eatlmatlon of longitudinal doaa dlatrlbu-

tion curve dlaplaeement and calculation of lta limita. Tha lac)c of auoh method oan

ba tha eauaa of ovar- or underaatlmation of the danger, what la equally unplaaaant.

Tha firat one lead* to protraoted delay In teohnlque development due to aaemlng dlf-

floultiaa, what la oonflrtned by practice. Tha aaoond ona oan ba tha cauaa of ae-

rlou* clinical mlatakeai In proton treatment.

Madia density along tha beam path can ba determined by meana of modem oomputer

tomography with tha acouraay not laaa than 0.1% (1). Evan If tha aoouraey of tha

+ Problama of tmnwreraal doaa diatributlon ahape are net conaldared In thia paper.

Che oheoae* usually a doaa field whoaa oroaa-aeetlon at 80% laodoaa oorreaponda

to tha target oroaa-aeotlon.

- 156 -

density Is evaluated several times higher than the real oi» the planning errorwould be not higher than some tentbes of percent of target 1'cation depth acoor-<Jlng to (1) and (2). Thus th* error due to wrong density determination is not mo-ra than 0.5 mm when lntracranlal targets (location depth is about lCv mm) are Ir-radiated, and \-'<t mm In other target irradiation.

tensity determination of the lung with Its variable linear dim nslorin and vo-lume le worth of a separate consideration. L*er.oitv oha/iges In different r«i-ta cfthe lun%, sited in {•'.), are In the range U.l«?f<.cm — • .44 g.cra "depprdin^ on suchfactors as patient's age, organism condition, i.rnath phnse. •• m the face of it suchdensity variations of lung density (especially due to the third factor} preludesthe possibility of precis* irraolatlon of thorax ljcated targets. In r»«}!ty inirradiation planning and Its realization i t la Important to determine exactly thedepth of target location . ' ^ t and target length • t 3 t as it bnn been shown•hove. As far aa the change of lung linear dimensions, volume and density in lungquiet state depends upon i t s air f i l l ing, the values • and t

/^ for the sa-

me pntient are constant in the same Irradiation direction. I'roper determinationof this values In course of prelrradlatlve preparation by means of computer to-mography excludes serious errors connected with lung density temporal changes ar.dch/uigts In different lung portions. This statement is wrong only In the o u t cfconsiderable displacement of lung tissues during irradiation session. It seeas tous that suoh dleplacenents are not great and do not provoke serious irradiationplan distortions when the breath i s oala. Nevertheless we are Intending to Investi-gate this supposition in first treatment oouraes. The technique and meare of suohInvestlgatlona are worked out by now.

Thus It oan be stated that the errors in evaluating media densities along thebeam path do not give substantial contribution in the total error when irradiatingany localization. If a proper methodological approach and modern topooetric Beansar* uflsd.

Let as oonsider the Influence of errors In media extent determination on theIrradiation plan realisation.

One oan demonstrate the validity of the expression

in evaluation of maxlaua ourre displacement at the zone of interest, where

' - error In determination of ceriia boundary position, on;t. .. - density of ajaoent media, g.om"-",

' . - media density in the zone of Interest, &-°* ' .

Generally speaking In i L calculations • t£ to the left and to the right of theboundary assumes different values. The quantities ' 1- mus* be taken with theirsigns.

i*t us use the above expression for maximum error evaluation when the bees} lastopped in two different target* - Intraor&nlal struotur* and new growth of thel'jnx* Error* du* to the wrong linear dimensions evaluation shall be considered on-ly so long as the »rrora in density evaluation by means of computer tomography are•mall and practically do not inorease the Irradiation risk, aa i t was mentionedabove.

In lntracranlal Irradiations the entrano* fields ar« ohosen as a rule ao thatthe bean on Its way to the target should go paat air oavlties and suooessively passonly through two media - external boa* oover and soft t issues. C*n*ltl*a of th*a*media are known well enough (3,4). The thlolcnen* of the external bone of a noraaloraniua in regions used for beaa entrano* 1* about 4-6 • • . In the d*sorlb*d oaa*on* oan aasum* the bone thlokn*se equal to 5 aai and use for lntraoranlal struotu-

- 157 -

rss and new growth irradiation a comparatively simple technique shown In Pig. 6.

Fig. 6:

The work of an elastic (water) ran-

ge compensator la Illustrated. then

the patient is rotated around th«

target oentre the dlatanoe fron the

point where the beam enters the ooi-

pensator to the lntraoranlal target

la oenstant due to compensator length

ohange.

Let us evaluate the mazlnum error of the teohnlqus by the expression (3). As--3 . - 3 .Burning bone - 1.7 g.cm . \ water • \ t i ssue - 1 g.om and the changeability

of point a a and b looation (due to the variation of bone thlolmees ) ' 1 •» * P.1) mm we obtain

- 1 1 . 7 mm I, U.7

I he rs»l rnatilmiun trror Is even eiwuewhat leea ainoe the density of a thinner ho-ne in somewhat higher thnn at thick on« and In aooordanoe to th< empiric dependene*

(see ref .J ) la

buns - l.flO - O.O24K (g.ora"^),whore X i e th« bone thlokness (mm).

This tota l error s a t i s f i e s the irradiation requirements for targets with l ineardimensions not more than 15-17 mm. Introoracial irradiations through a water oom-pmnnatnr hna be»n f i r s t employed In Berkeley (5) . In the 03>R It has been workedout at ITEP and Rourdenlco i ic lentif io Hssearoh Inst i tute for Nenrosurgerj and Isuaed in c l i n i c a l praotlos at the IT El proton beam alnoe 19P5.

Let ua consider one of ths moat complicated caaes of the beam stop Irradiat ion-irradiation of the target in the lung. This o l ln ioa l oaae 1« really the most co»-plioated one for two reasons. First of a l l ao far aa lung tissue density grentlydi f fers from that of other organism t issues and structures the qu'intlty 'In the expression (3) roaches i t s maximum value at the lung t issue boundaries. Be-s ides that ths number of media on the way to the target i s In this ones more thanIn Irradiation of other targets , such as prostate gland, skeleton bones, objeotsIn abdominal oavlty e to . Aooordlng to the expression (3) the maximum possible er-ror Is lnoreased for both reasons.

The madia atruoture whloh the beam passes on I t s way to the target loca l i sedIn the lung Is shown in Pig. 7a. Assuming the p o s s i b i l i t y of topometrlo error

M • - 1.5 ran in determination of eaoh of five madia boundaries and using asformerly the expression (3) we obtain ths aaxlmum possible displacement of thslongitudinal doss distribution In the sone of Interest (target boundary) at thepoint 4i

-13 am .. 1 4 -- ±3.5 mmand at ths point 5t

- 5 mm '. d L j ~ +16 mm.

Bearing in mind the smooth oourse of longitudinal dose distribution ourve up

to ths target (Tig. 7b) one oan state that ths error at point 4 doss not lead to

any appreolable degression from the Irradiation plan. Dose alteration near the tar-

get frost boundary oaussd by longitudinal dose distribution dleplaoeaent O.5 mm

- 158 -

''A

|

°

>/ ,A

A

^,-* i i.f I <??• i i ! • »

fig. 7:

a) media struoture in out of lung

new growth lrradlationt b) longitu-

dinal doae distribution looatloa ae

It la planned^ o) maximum displace-

ment of longitudinal dose dlstrlbutlt

caused by topoaetrlo errors* d) ln-

tantlonal longitudinal doe* dlatrl-

butlon «zt«naion whloh laauraa tb*

wbola t«r(*t Irradiation.

forward or -13 ma backward la lnal&felfloant In the targat ltaalf and at tha way

to It (?lg. 7o).

Tha error at point 5 lnvolraa much grartr ooauaquanoaa. Hara tha dosa gradiant

Is high and error. & L. ahown abora la fraught with target undarlrradiation astan-

ding 5 mm of irradiation of sound tiasuaa by 80% - 100% doae axtandlug 16 mm ba-

hlnd the target (Pig. 7o). Both oaaaa are inadmissible.

Uevertheleas the situation aeena not to be hopeless. Irradiation of tha rear

part of the target by the right Aoae (80% - 100%) oan be ensured If dose distri-

bution ranging 5 g.onT^more than It Is ehown at Pig. 7b is used. But the extent

of possible 80% - 100% dose intrusion into sound tissue behind the target (Pig. 7d)

laoreoaes tn the same time up to 36 mm+. Up to now we have discussed Irradiation

from one direction (one field Irradiation) whloh la never ua«d in such casea. The

use of multlfield rotational irradiation substantially levels even this most un-

pleasant effeot (36 mm overshot).

Let us Illustrate the abore statement by an ftxanpla In tha oonorete. The re-

sults of two-dimensional modelling of a circular target (60 mm in diameter) Irra-

diation by means of a computer SH-4 are presented In Fig. 8 ano 9. The flrat one

Illustrates a multlfield Irradiation from 10 dlreotloas with rotation around the

target centre In 270 degrees seotorj the aeoond one - from 14 directions with 360

degrees rotation. Two irradiation variants hare been modelled In each oase under

following conditions: variant "a" - laok of error, deep dose distribution in a

single beam isee Pig. 7b)| variant "b" - presence of maximum error ( L - 16 B M )

and additional 5 g.om"2oorreotion (increase) of the range depth In a single beam,

i.e. use of deep dose distribution In a single beam as shows In Pig. 7d.

Total doae distribution la transformed In the second variant. In this oase the

region of 80% - 90% isodos* does not ohange practloally, and the dose gradient la

slightly decreased. The preeanoe of error and our oorreotion of deep dose distri-

bution, whloh ensure* reliable irradiation of the whole target VOIUBM, provokes

+ The extra 5 g/so» (5 asi) we added to the ranee In the target approximately cor-

responds to 20 ma range In lung tissue behind the target. This additional rang*

la «u«narl»ed with 16 sai error.

- 159 -

i

Pig. 8s

Cos* distribution obtained by neons of a oonpvter in multlfield rotational irru-

diation of 6 mm disaster target looated in the lung. Rotation angle - 270 degrees,

nunber of fields - 10j a) irradiation nodelllng when depth dose distribution shown

in Fig. 7b is used) b) irradiation Modelling when a oorreoted (extended) depth do-

se distribution of a single beam shown in Tig. 7d Is usedj o ) one of dose distri-

bution seotion deformation (A-A - without oorreotlon, B-B - oorreoted).

Fig. 9:Tha saae as In Fig. 8. Rotationangle - .160 degrees, number offields - 14.

the appearanoe of "uncertainty tones" (oross-hatched In Fig. 8o and 9o ). Lineardimensions of these tones are about 7 am at 709 lsodose and not -nore than 10-16mm at 30% - 50% isodose. Nerertheless in oase of wall localised target Irradiationtotal dose distribution remains laaeaeurabl? aore effeeHlre than that of field*in gaama and eleotron irradiations, whleh are widely used (see, for exaaple. Fig.10).

Conoluslon

1. Tha ohoioe of proton irradiation teohnlque - through irradiation or irradia-

10:

Loae topographloal anatomy card of the lung new growth Irradiation.

tlon with the beam stopped In the target - la determined by th« target dimensions,

neoeasary dose at the targat and toleranoe of surrounding tissues and structures.

2. Planning and realization of beam atop teotmlque Is always nora complicated

thar In cans of through Irradiation. The oholo* of adequnte energy of the lr coming

beam In order to lta preolee atop In the tumour Is of great importance.

3. Topometrio errors In madia geometry evaluation on the beam path which lead

to unforeseen displacement of the beam atop point can be eatlmated In count of

treatment planning.

4. The evaluation ot possible error* and a correspondent Irradiation plan cor-

rection allows to avoid serious defornatlona of total dose distribution ev>- - If

the target is localized In a complicated heterogeneous part of organism.

Abstract

There Are two techniques employed for proton Irradiation - to pass a protonbeam through a target or to atop In i t . The benefit af the first technique la avery email angular divergence of the beam penetrating tlaaues or, ooneequentlj,a rery high lateral edge field gradient. The aeoond technique has two additionaladvantages - the abeenoe of radiation esiona behind the targat and the increaseof the stopping power (dose) at the end of the bean range loooliied In tha targat.This paper presents considerations concerning the applicability of each teohnlqueand certain charaoterlstlo problem* of tha seoond technique. Dose field deforma-tions because of tha topomatrlo uncertainties are also estimated. A net hod of do-se planning alaed to minimise the effeot mentioned abore Is proposed.

Raferenoe»

1. l.v.Rubaftor. V publlkaoll "fundamentallyja naukl - aadlolna", Hoalrra 1981,atr. 246-250.

2. K.Merkle, O.H.SpasokukoclcaJa, S.J.Jer. onin. Kompluternaja tomograflja • o-

- 161-

pr*del*)itt plotnoatl ío ttioh ill pl*nifovMtii obluCanljs, Ma^toínatcaj* radiolo^i-

ja, 1963, N.9, tr 31-34.

3. S.P.IAaoveo, B.I.Ratnik, M<dioinakaj* y^diologija, 1982, N.č, atr.36-39.

4. 3.f.LiacTeo, V.I.Rtznik. Iaučtnij# tormotnyoh apoaobno<t<j mat<ťl<J.ov dl*

gftsrogannyoh fantomov č*rapa.. MtAioiB#itaj* rtditlogij*, 1980, N.9, 'tr. 71-72.

5. R.N.Čalbarg. R#,dloblologij*, dosimatrij^ i <t*r*ot*kaHaak*j* tsohnik* prl

radioohlrurglč*<koH eblu3*nii protonay* pučkem < l#poI*ov*nl#H plk# Bitgg*. V <b.

"IapolHOT<mt# prototmyoh pnčkov v ltičavoj taTapll", vyp. 2, Motkv*, Atoml%d*t

1979, atr. 69-65.

6. A.I.RudtrMn, K.Š.Va-jnbarg, K.I.ícHiYar. Diattnoienntj* g<tiOM-t#r*pija

Klok*S#atvaBmyoh opuoholaj, M#aioíJM, 1977, atr. 222.

- 1 6 2 -

IV.R A D I A T I O K P R O T E C T I O H P R O B L E M SI N R A D I O T H E R A P Y

IV.P R O B L % M Y R A D I A Č N E J O C H R A N YV R Í D I O T R R A P I I

DOSES TO PERSONNELB;GA3ED IN RADIATION TREATMENT 0? CANCER PATIENTSm K^AiT DURma 19B0-05

Ypualf Y. Bakir, Sulaiman D. Al-Zenki, Jozftf Sabol,Radiation Protection Division, Ministry of Publio Health,Kuwait

The paper preaenta reaulta of doaes to radiation workers in Kuwait over a fi-ve-year ptriod 1960-65. The speoia.1 attention haa been paid to analyaia of radia-tion exposures of tho peraonnal involved in radiotherapy treatment of cancer pa-tient*.

In Kuwait, radiation proteotlon ia organized In aocordanoe with the Bniri Dec-ree issued on the 12th November 1977 promulgating Law No. 131/1977 concerning thesafe uae of ionizing radiation and.precautions against its hazard. The RadiationProtection Committee represents tha highest authority in the country regardinglegal aspects of radiation protection, while the Radiation Proteotlon Division,as an weoutive body, is responsible for implementation of the baslo la* c* wella* deoieiona of the Radiation Protection Committee.

One of the main duties of the Radiation Protection Division is personal moni-toring of all radiation workers in Kuwait. ?or this purpose film doaimetry ha*been used. The films are usually worn by monitored persons for one month. Thanthey are returned to be processed and evaluated in the Radiation Protection Divi-sion where monthly, quarterly and annual reoords are produced and kept. Result*of radiation exposure are reported to employers monthly and quarterly.

Table 1: Radiation workers in Kuwait

}*** Total

Application

Llagnostio radiology

Miclear aedlcine (andother uae of unsealedacuroea in medloine)

Radiotherapy (externalb?ama, braohytherapy)

Industrial radiography

/tha ra

Total

— *11980

324

12

73

27

116

552

Nuc

1981

394

16

69

46

120

665

tber of

1982

466

18

97

50

134

765

worker

1983

541

24

124

66

131

906

<

1984

546

26

112

89

142

917

1985

611

31

114

92

151

999

Table 1 ahowt the distribution of radiation workers between the main groupsover the 5-year period. These data dearly Indicate a steady inoraaae of oooup*-tionally expoeed persons especially la the field of medical applloatlon* of ioni-zing radiation and radionuolldta.

The annual dese distributing *f all r*dl*tit* werkers are presented in Table 2,where number of workers reoelviag dost* falling into stated range* are given. The

- 163 -

number of peruona with highar doca* or orer«iposurea decreased subs tan t ia l l j whlohreflects inoreased experianoe of personnel as well as Implementation of nor* ef-ficient rsdiatlon proteotlon measures.

Lose distributions presented In Table 3 are related to the radiotherapy person-nel (including external beam therapy, braohjtherapy and the use of unsealed radio-aotlve eeuroea).

Table 2i Annual dose distribution of all radiation workers (numbers in bracketsare expreaaed In X)

Ltoee equlralentnxSr

Number of radiation workersT9B1 T 19Q2 I 1983 f l-484 ]~~19P5

i

0 - 2

2 - 4

4 - 6

6 - e

8 - 1 0

10 - 20

20 - 30

30 - 40

4 0 - 50

50

Total

12(2.2)

6(1.1)

4(0.7)

6(1.1)

552

1

( 0 . 1 5 )

3( 0 . 5 )

3( 0 . 5 )

4( 0 . 6 )

665

8

(1)

1

(0.1)

(0.1)

4

(0.5)

765

2

(0.2)

2

(C.2)

1

(0.1)

(0.1)

906

1

(C.I)

1

(0.1)

917 999

Table 3i Annual doee distribution of pereonnel engaged In radiation treatmentof oanoer patlenta

Dose aqulralent

•ST

0 - 2

2 - 4

4 - 6

6 - 8

8 - 1 0

iC - 20

20 - 30

30 - 40

40 - 50

50

Total

1980

11

2922

41

e1

76

Nuaber of persona

1981 1982

76 90

13 1021

1

1

96

1

107

1983

128

1984

1068 8

1 3

1, | 11 1: 1

138 120

1985

X231

1

2

126

- 164 -

In order to u i a n the actual • l t u a t l o n and trends regarding the doses reoeivedby radiat ion workers and to compare between average doses of a l l worker* with thosedealing with radiat ion therapy ava i lab le personnel monitoring data were rearran-ged and aummarited in an appropriate fora in Tabla 4 . In s p i t e of high radiat ionl e v e l s typ ica l for meet of the radiotherapy treatments annual average dos«s arelower than average doses oaloulated for a i l monitored persons. Actual ly , exoeptin 1980, these average doses are considerably below the ICftP dose l i m i t reo cones-dod for memtors of the publ lo , i . e . 5 mSv.

Tabla 4: Annual average and o o l l a o t l v e dosea of a l l radiat ion worker* and radio-therapy personnsl

Year

I96019811982198319S41985

All applloatlons

Arerag*doe* mSv

5 . 92.72 . 4

1.71.51.3

Oolleotivedos* man.mSr

329817691846153713761265

R»dittlon therapy

Average Colleotlredose m3v dofis ma&.MJSv

5.12.51.71.21.51.2

390237179164176144

KF.A3'JRKMKOT 0? » TiBEfi ALBEDOport ;.AC;-I..CAT:'£::£I: 662 k«T PHOTOSS

A.Bhattacharjee and A.K.Slnha,I>epaxtment of PhjeloaRegional Engineering Col lege , Sl lohar - 788 OKIr.dla

(Assam1

A suitable combination of Rtratlfied layers of different oateriala and thiek-ueeses has teen found to increase the shielding property for gamma raye. AlbedoIs uee6 In £>uch measurements as a parameter for the Integral measure of ganna r*yecKtterlng. The Uniform Sensitivity Photon Counter designed indiganeou«ly has beanused In the present Investigation. This Counter has an advantage ever multlohannalgjmlyntri' alnce results are obtained in a straight forward manner and does not re-quire response correction by Invars* matrix method as Is the can* with a •ultlohan-nel analyser. The differential and total number albedo values for the stratifiedslabs of conorete ftnd lead at 662 lc*V energy hare be^p reported here.

1. Introduction

Number albedo measurements for s*nl-infinite aoattarars hare been oarried outby several authors ( 1 ^ ' 6 ) . But the literature on albedo measurement* for binarylayers is almost n i l . Hyodo (7) oarried out measurements with etr»tiff5d layer*

- 165-

o f ^ l n m i n ť i m Ail's t ti. ?;*).'iť* i' i n v a H t . i c u t ř f S t h e a ^ f a r t ť f t a M i l f - i w h t i m r s t d t r .

f i < < [ . t u f < * m i - i t [ f t ' t a t ' ' " ! ' * t 9 n ] * h < ! . I n t h K r r t a t K t i r t v f a - l u t t t t t . n ď i f r t r * ! ' ! * !

ar.f*. trťiJ ntmter ^!be<1o mfamframat.te have heen rnrried ''ut fnr etratlfied layere

nf concrete and lead for í' 2 keV ['hottr.a.

;.'oat .f th" KiShf.r< hRvt< rRrrlcd cut manxuremertta nf nimtmr alhe'tn for hn--)<*r*xt-

tor*d^rtfn]třt!tty*w!th'.!'\'*MM'!:'tíťrftM!n*c^t]nt!ii%ay*t*MO<^;lW'l*!tt:!utaMtr'):*S!.-

nel nnwi-Hor. "}<t !<tok<sa'^'.ered fôtfna have m)Ted ener^tee miC the apoct^tm rtmd-

ed ref<i<<r.Be -orr<!cH<'n becňuňe of the dependence of t.hí (ia'xctor «fťlc!#r.oy on ln-

olánnt ph<-<tnn "tinr^- ?h* 'nlfortn Sennitlvity Thotcr Cosir.tftr 'tsať irt he p:

lt.<n 1« inJ#p^n<)<ct of r#HtunB< c^rr*otton.

.t nRn r.*!#n <hown by 'ihfsf .'.<, that th< efficl#ncy of * d n t l H a t l " r T tr.třr

may ha m^ťe tmifcnn by unjn^ ň fiít*r of auitabla matsrlal arrf thirtmôs "''Tr^

a i. 1 'TI; cryatul. ?^r paraylal incident y-rays, the efficiency of ťn« **'.lt*r

cr.'^tai 'Oici'r.Rtlnn lň rtprOHaritec by the equ^ttnn:

tshpre a and b are the thlckneaeea of the řryetňl at;d th^ filter r«npňctivřly, ř

aji: *p th^ total ard non-coherent abaorptlon or<-#f!'leient r.f thf r^Rtnl And the

filter .-"Hpectlvaly anč f JB a n'imer)oal weight factor whtct. fure.T^ndu to the

frurtlon of ttme for which the filter i< ultced before the f.;i'sta]. .'?ir.!-.e equation

\t ) i< linear w]th f, It i« evident that for a particular <et o! valupR <,f a tn(!

b <m<(.' fur different value* of g<UMta tuy enerîeti the t Va f linea will irteraect

at n pt'int. Fir thla value of f the *y<t*m will have cnnwtant efflrlenriy for the

amne energy range under consideration. If (r It calculated frr the ph)tnr. ener-

gies under onalderation ming the optimu* value of f the effloler.oy of the com-

bination la found to remain constant *-a Hhown in fl^re 1. In the prexant Invest!-

06.

I Q^; Variation of oalculatef! efficiency

^ ^ with energy for f - n . 8' - O.B

o o'? ó'<. & óá it) i? '* *

Ration the material of the ftlter ie alumlnltun of thlckneae ' gm/f-m , th^ ery*-

t a l i < * ; " ' X ; ' " N a ! (Tl)<clntill*toraj.dthe -rtisma value o f f Is.l.r.

method

In the preaent inyeatlâtlon the atratlfle^ layera of conoreteand lead 4n em ^

^0 om x í om and 40 om x 40 om x H.l om respectively have beer. uafd. Fn tr typeo

of confiřruration have been used. In the flrat configuration L.C., lead la kept aa

the flrat layer and in the aeoond configuration C.I . the cc.nrrete plate h M been

uaed a* the firat layer. In L?C, configuration two lead platea have been placed

before one oonerete pltte and the arrangement has been repeated, ir L-C. oonfliru-

ration thrê platea of l**d haye been us#d before on* plat* of oonrete. The lao-

troplc 137^ souro* of nioro-curl* strength ia placed at the p<int of interaeetlon

of tie oentr* of the fir<t ltytr and the *ni< of th* detector. The &lt<rnate aoat-

t*r*r alaba are placed on * goniometer oe.librat*d in d*gre*<. The angle la the

angl* between th* norami to th* nurf*c* of th* *oatt*r*r and th* d*t**tor aria

<Lnd la m*a,aur*d at tnt*rv*.l* of 10° from 0° to 90°. To *H*tn*,t* forward aoatt*r-

- 166-

eó rH^lAtínn <At the 90" position th<! ďateotor is plaoed oloee to 90°.?h* ocnvmt onml #lectr^nlc oircuítry oonnlsta of a p'<lee amplifier. Bln^le

ohitinel &jíalyřter < nd denade Hoular.

<!. RpBulte and di^cnHaipu

Tha differential number albado N. (ň,x) for a particular angle -* and alab thick-ness x ia expressed by the fraotion of photons emerging at the angle " per stera-diaa and for one primary photon Incident on the acatterer. The number of b;..i!cscat-tered phutnna Is obtained by tha differenoe between tho integral eounta witn andwithout the eoatterer uaing the above ocunter. The total number albedo values tr#obtained by integrating differential valuea over angular co-ordinates. Th< ffen-tive atomic number of the alternate layers of lead and oonorete has been cu.cul*-ted on the procedure followed by Berger and Rtao ď . J. The weight fractions oflead and concrete W- and W have been determined assuming that the heterogeneouslayers of lead and oonorete may be raplaoed by a homogeneous mixtur* of calcula-ted effective atomio number.

Tho quantity whioh diattnguishes the baoksoattering from one material from thatof anothor is the ratio of the scattering oo-efficient (^*) to the total atte-nuation oo-efficisnt ( D ^ ) . The total attenuation oo-effioisnt and the aoat-teriAg co-efflciant t^-) of the mixture for various energies are obtained usingthe formula given below:

" * (HI) - .-* (L) (Kl) L ^* (C) (ML) -c

. ,* (L) ( M ) -, * . * (C) ( M ) Wp

The ratio of *//< are oalculated at various energies. Following the abcve<?^*/// * for various pure elements such a* Na (11), Al (13) Ca (20), ?*

(26), Cu (29), Fb (82) and U (92) have been computed. By Interpolation the effect-ive atomio number Z - of the binary layer *tas been determined.

The total albedo values for lead and oontfete soatterer* are shown in figure2 and 3 respectively. The total albedo values were obtained for three different

. , . W

-f" rfh- ' ,

M g . 2:Total number albedo value of leadat 662 iteV energy as a functionof acattsrer thickness

?ig. 3:Total number albedo value of oon-crtte. s.t 662 keV energy as a funo-tion of seatterer thickness

bias settings and the extrapolated value of total albedo at sere bias was obtained.The total albedo values for stratified layers of lead and oon*r*t* in configura-tion* L.C- I^C. and L.C. at 662 keV photon energy have been shown in flgurw 4.It Is observed from these figures that the saturation thlokn*** of oonerst* re-duces to a great eitent whan laa-t *o*tt*r*rs *r* alternately placed between ooa-orete soatterera. The distensions of individual aoattar<<ra, their atomio numbers

- 1 6 7 -

100,

°O.I6

Í0J2

E

oa

oco I

6 6 : )Qs CompotUt Hyf r

L;C,°Lt . t,

L!C,-Li . C ,

H g . 4tTotal numbar albado valuaa of oompo-aita layara of laad and eonorata inthraa diffarant eonfiguratioa# <M afunotion of aoattarar thioknaaa

K g . 5!Diffartatial number albado valuta oflaad, oonorata amů thair oottpoaital*y#rw *# a řMa#*iea of tatyglafat 662 k#V anargy

and tha affaativa atomio numbar of tha oompoaita layar ara ahosm in TabI* I. Itia obtarvad that tha aftaetiva atomio nuabar liaa batwaan tha Z valuaa of ooncra-ta and laad. Tha diffarantlal albado valuaa of th* ooapoaita layar lit batwaan

Tabla It Configuration and affaotiYa atomio nmnbar of laad and oonorata in atra-tifiad layara at 662 kaV anařgy

Configuration

^°I^Cl

b°i

Thloknaaa af aaohOoapanant layar

in on

Laad

0,3

0.2

0.3

Conorata

2

2

2

No.of plataa ofaaoh alaatanttakan in thaOanfiguratiam

Laad

1

2

3

Conorata

1

1

1

Waight fraotian

*L

0.171

0.292

0.382

0.829

0.708

0.618

Caloulatadaffaotiv*AtamioNuabar Zaff

46.61

56.04

60.43

thoa* valuaa of oonorata and laad aa ahown in figufv 5. Tha total numbar albadovaluaa of oonorata laad and thair binary oompoaitiona ara ahown in Tabla II.

Tha total albado valuaa for eonerata and laad oompoaitlon in two etratifiadconfiguration L^C^ and C^L- with laad and oonorata na tha firat layan hava baattahown in figura 6. Tha hiatograph ahowa that tha total albado valua ia highar whanoonorata alab ia uaad aa tha front layar. Tha diffaranoa in tha total albado va-luaa for tha two configuration* ia mora than 50%. It indioataa that tha affaat ofbaekacattaring from tha firat layar ia aignifioant and tha baotcaoattaring of gam-** raya moatly ariaaa in tha raglon naar tha front aurfaoa of tha alab.

It t* obaarvad f#om tha graph* and the tabla that tha numbar albado valuaa da-craata with inoraaUng atomio numbar. Thl* ia baoauaa tha oroaa-aaotion for photo-alaatrio abaorptiom iaoraa*M with iaornning atomio numbar. For tha lama raaaom

- 1 6 8 -

Table IIt Total number Albedo valuaa of Conorete lead and their binary configu-

ration* for 662 keV Photon*.

Klement/Canfíguratlta

Cenorete

h°l°11^ 1

h°ii**d

ZerZeff

13.5446.81

46.81

56.04

60.45

82

Number Albede Value*

Pre*ent inYeatigatiem

0.45 - .010.145 i .01

0.3175* .01

0.115 - .01

0.096 i .01

0.0821± .01

Sinh* et al

.405 i .01-

-

-

-

.105 -.002

Hyed* *t al

--

-

-

-

.09Í.02

T40.

-o;

C;L, . L, . C,

6s

Tvtal number *lb<do Y<ú.u<o for two configuration*

1^0^ <md C^L^ for 662 k#V <a*rgy *< # funotioa of

<oatt<ring thioknm

th# total number Alb.do vttlu. for th< xtMtifl<d l&y*r< li* bttwttn tho<* v*lu«

of oonoret* and la-d. Th* for#going oburvatlon* ol<arly iadioat* th* aharp d+-

oraaa# of b<tok«]^tt*ring of gamma r*ya and r#duotion in saturation thiokmaaa by

th# lMřrtlon of a .lab of higher atomic numbtr in a aoatttrtr of lowtr atomicnumber.

The tmthora are grateful to th* Department of Atomic i&ergy, Oovemmwtt of

India for finanoing the project. The author* are alao thankful to the Principal,

Reglon&l Engineering College, Silobar for hia kind intertat in the work, and one

of the authora (AB) eypreaaea hia gratitude to the College authority for the kind

peraiaelon accorded to hia to undertake the reaearoh work.

References

1.

2.

3.

4.

5.

9ie.

6.

7.

a.

9.

10.

T.Hyodo, Wuol. So.Bigg. ^ (1962), 176.

D.B.PotdnayeT; Joum.Nuol.Engg.gi (1967), 197.

M.Blawaa, A.K.Sinha and 3.C.Roy Nuol.lnatr.Meth. ]J^ (1979), 157.

M.Biewaa, A.K.Sinha and S.C.Roy Joum.Wucl.3e.Teeh. JJ (1990) 559.

A.K.Sinha, A.Chattarjee, A.M.Qhoa* Proo, 2nd Int.Sy*. Radn.Phy. (Panan$;-19a3),

A.K.Sinha. Proo. 7th Int.Con.Medioal Phy*. Vol. II (Htlalntl - 1985), 114Í.T.Hyodo. Joum.Wuol.to. Teoh. í (J.96H), 458.M.Nakata.ihidAa(196l), 263.

A.M.Ohoae,Wucl.Inatr.Meth. Jii (196?), 49.

M.J.Berger and D.J.Rago.Badiation R*<. i2<(1960) 20.

- 169 -

DEPENDENCE Of E??BCTIVE LJBEAR ATTBNUATIOH COEFFICIENT

ON X-RAY TU3B VOLTAGE RIPPLE

T.Porubs iky , bTedioor, Budapest , Hungary

Ths so-call*d non-lnvaaiv* X-ray tub* voltage measuring d*vloen g^narnlly u»*signal* of two d*tectors having copper fi lters of different thicknesses. Althoughthen* devices are conventionally oalled peak kilovoltage (kVp) meters, lnf'luesoeof tube voltage and current waveform* on the measurement reeulte need eon« oonsi-deratlona. One oan choose only the calibration* corresponding to the oonventlonalrectifying systems even on devioes of the highest level) some other types provi-de only two calibration*! one for cingle-ph*ee and an other for three-phase wa-veform*. Although ID the USA there i s developed a devlae oepeble for measurementsof medlun frequenoy X-ray generators (Vlotoreen KKRO-C), however, i t is a varyexpensive top devloe. It seems to be unsolved all over the world the daily non-invasive X-ray tube voltage measurement of medium frequenoy X-ray generators. Con-sidering that most of these generators are aonotank types where voltage dividermethods are not applicable, i t oan be seen that solution of this problem is veryurgent.

Theoretical bases,

One of the physical quantities us*d for oharezoterltlng radiation quality Isthe so-called effeotive linear attenuation coefficient. It can be defined fromthe following ezpreaslont

Y ^where J Is the energy fluenoe rate (or with older tenalnologj "intensity") ofthe X-ray beam having originally a Yi energy fluenoe rate, passed through an ab-sorber having a thickness x, S i s the photon energy, /f Is the linear attenuationcoefficient of the absorber. % /K/ means speotral distribution, fa oan be expres-sed from this formula:

L m - -i-lmJL (2)

It can be seen that value of /f depends upon not only the kind of the absorberbut on i ts thiokness x, too. Therefore /I oan not be oonsldered as a oharaoteris-tion of the radiation but that of the Interaction of the absorber of the giventhlotnees with the radiation. Its value oan ba determined with ths aid of detec-tors of energy integrating mode. Detector* o* non-invas.lv* X-ray tube voltagemeasuring devices oao be considered to be suoh types In a good approximation.

Our goal was to oaloulate the dependence of / / on tub* voltage pulsation forestimating the attainable aoouraoy of non-lnvaaiv* X-ray tub* voltage measuringmethods. Aoouraoy of determining peak kllovoltage by non-lnvoalv* methods la l i -mited aa only such differenoe* of illovoltag* oan be distinguished that oausehigher differences In ft than the •azioua ripple dlff*renoe* for th* sasj* peak kl-lovoltage.

yprarulaji

The calculation 1* ba**d on formulas glv*n In an *arli*r paper. Taking Into

aooount *o»* known expressions (1 .* . m*a» attenmation ooeffioientj of mixtures.

- 170 -absorbed doee from a polyenergetlc beam, averaging of tlm« dependent quantities)we have obtained the following formula for the absorbed dose fron narrow X-raybeams generated by pulsating potential X-ray generator* having any waveform, pas-sed through any attenuating medium:

F. maa

L '' ^ ( E , x ) , E . B ( E ) dE (3)

where

A(E) - a W - J j ^ • 1 U ' ) f ~ ) i ( « ) V <«'>**, «*)

and iB(B) - f ' / o l M ( t ' ) , K ) . i ( t ' ) d t ' ( 5 )

owhere i ie the space coordinate, x«0 is the point of origin of the X-ray t<eftm(tube focus), x is the position of the tube h'-usin? window, t is the time, x istho 'iuration of the irradiation, T i s the period time of the tube vvitaire, E inth" photon enorgy, j ie the speotral di ntributioti of (photr.n) f]uei.oe rita withrospeot to energy normalised to unit 1 nni J,^ i s the density, /f/S ie the massi t tai-.uat ion coefficient, / f e n / ? i" *he mass energy absorption coefficient ar.d I;is the ibsorbed dosa. The quantity in sqtr.re brackets repr».')ents the mass attenu-ation coefficient of an n-component compound cr mixture In which w. is the frao-tion by weight of the 1-th oomponent and (/</? )1 Is Its masc attenuation ooeffl-olont. A/E/ expresses the total transmitted fmotion of photons of energy :•: ot thebeam paased through all the attenuating media while B/E/ represents the averagefluenca rate speotrum normalized to unit dljtanoa from the tuba foous without at-tenuation. In the formulas all variables are written as arguments. Tha inherentfiltration of the X-ray tube is Included In the fQ apaotrua while added fi ltersare to be taken Into aooount among the attenuating madia.

Based on the formar expression, the fluenco can ba written In the followingform: *

E aax

T.X~ B

while the energy fluanoa is

E max

A(E).K.B(E)dE (7)

I'

t.x2 a

(Theaa equations do not inolude the contribution of the scattered radiation -narrow-beam geometry - aa this contribution can not be eiprassed in auoh a direotform but can ba estimated using some approximation methods).

Taking expressions (1) and (7) into consideration, ^ can be calculated for anyU(t) and i ( t ) waveforms and x copper f i l ter thicknesses.

Results

A computer program has been written for the oaloulatlon of ft. In tabla 1 oaaba seen the U/t/ and 1/t/ idealltad /analytical/ wareforais whloh ware used forcalculations of the given generator types. As the application of the Hated M T I -forms was not enough for oonolusiona, calculations ware aade with soaa "defor»ad"6-pulsa wavefonu, too. It means that siaa warea oonprassad alcstf tha t->«LXla arasuperlaposad but six ones oorraspondlng to the awlclnal period t l»s . Tharaforathe tlaa interval for oaloulatlon la imohanged / I . a /0 , T/12//, but uslns the ldan-t l ty

+ 1 la tha tub* ourrant,// la the. tuba veltafw

- 171 -

IX 1•la 2%L-~ * -J-

\* •• k—fold oompr*aaion

12

oo. 2jC* ( — LT 12

la Died* whloh for k»l naturally givta tha original valuta. Aa for aln* functionoaa twtlfth of tha ptrlod la 7C/(>, thertfor* ualng

ota k • - a6

tha valuta of k war* dtttnalntd for glvto

valuta.

nln' B

Ta,bla li AnalytloaO. approximation* of wartforma

Sjrabol Typa j Tuba voltaga i Tub* ourrtnt I Tim* _int*rraj. j<t ' 2 pula* I T / t / U a l ^ 2 T - i i /t/ oVt/ j o t J- I

but U/t / 26 kV

I 6 pulat

i

I 12 pula*I

40* spik*4 20* aplk*

10* splk*5* aplk*

Conatant

V1

U/t/.O,max

+C,

u/t/-u

u/t/.u,max

1+aln

1+008

'3-f-

0

0

>' !

h

any

T la the'period tim*. WaTaforms oorrtaponding to th* givtn tlmt intorvale are rep*attdinttger timea within T. Thua thar* la tnough to calculatt for on* lntarral. Valuta ofth* conetastac

C2-0.6 C3-1.2Typ* 3s Cj-1Typ* 5t Cj-0.4 C2-0.9 Cj-0.3

Typ* 4: Cj-0.8 C2-0.6

Typ* 6i Cj-0.2 C2-0.95

Tabl* 2 ahowa tha ua*d data wh*r*

R - ( (8 )

1* th* *o-oall*d p* roan tag* rlppla. Calculationa war* p«rfor«*d In tha ao-oall*doharaottrlatlo.. tub* current approximation, i . a . tub* ourrtnt la taken a* a pow*rfunotloa of tub* voltas*.

For 0-3, 4i 5 and 6 /mediua frequency/ generator type waveforms the R pulsationwas determined differently from the former standard formula. As In these oases tu-be current and voltage are constant in 75% of the period time and pulsate only la25* of i t , for these waveforms 25% of the value given by the standard formula < uconsidered to be the percentage ripple, lor these waveforms.

Conclusions

A research work for constructing a non-invasive X-ray tube voltage measuringdevloe la being cade in VNIIIKT * liosoow with the active cooperation of X-ray Di-vision of Hedloor Budapest. This work waa a (art of this cooperation. Aa experi-mental oonflrmation was made for aone pulsation values, and measured results areidentical with calculated ones within the measuring accuracy. (However, i t Is dif-ferent to compare mor» experimental values as the degree of pulsation oan bs in-fluenced only slightly in most generator types.) Preotioal ooastruotloa Is beingmade by colleagues of the VMIID1T A.I.Lelohenko and T.V.QanlleaJco.

An essential oonolualon can be drawn from the figures for kVp-aeenring withla5-6* aoouraey two calibrations are sufflolent< one of thea for 1- and 2-pulse ge-nerators and the other for all other types ( i . e . oonetant potential, aedlua fre-quency, 6- and 12-pulse).

We intend to publish our results la the near future la a Joint paper to bspublished la the Soviet journal Meditslaskaya Tekhnlfca.

Reference

Perubaxkyt Phye.Uo4.Blel. 3JLt 371-381 (1986).

. Ali-U«l« aeientifle Re.earoh lastitute fsr M««l«*l Ia«i>eerla<

- 1 7 ) -

t,fl-

PH(JM10T0 300kEV

F.řemiíka,

Inntitute of Radiation

Cr.echoal vah Aoademy of Solenoea,

Ba Truhlářoe 39/64. 160 86 Prague 8,

CBeohoalovakia

X-raya have been uaed in dlagnťstloe and therapy praetloally ainee thalr dla-

oovery in 1966. The X-ray beams are usually oharaotertced by voltage on tub*, cur-

rent and filtration. Sóma people atate HVL of the beam <r <tn effective energy.

All theee paractatera are very uaeful but not !n « H <-a<m th«y ar* auffloiant to

daaorib* fully a partioul&r aituation.

It ia a well (mown faot that the quality of an imnm in a diagnoatio ayataa

<!apend# on th< mount of acattertď radiation. Th* itange cont!-Aat ia aignifioantly

rtduoad du* to ecatterad radiatioa. Naw taohniquta dayelrpen tc reduoa th#aa vf-

fecta and thua improTing th* imaga quality of the ayatem can b* taatad by Montt)

Carlo aimulation. To maka auoh a almulatlon affuctiYa one haa to kno^! tha whol<#

primary apaotrum.

Another aituation wher# tha affaeta of tha mattered radiation have bean en-

oountared and 3ncumeEted ie for exampla meMur*m*Mt of an abaorbad doae and oa-

libration of dofxsmetara. Figure 1 ihowa three fluenoa apeotr* for generating Yol-

?ig. 1:

Flueno* apeotra, mean ena^*-

gloa, and affaotive anergiea

tagca 60, IOC and 250 kV with different filtration. They ware taken from litera-

tura /I/ and normalized to their maiimu* valuea. Thla figure alao ahowa the ef-

feotiYa energlea oaleulated from HVL and the mean energiaa aa oaloulatad from

apeotra. The difference *a muoh aa 30% haa been aohleved.

The meaaurement of an abaorbed doae requirea tht knowledge of auoh a paraae-

ter like the ratio of atopping power for medium and air. Tha ratio of S*M weigh-

ted by mentioned apeotra to one o*lculated from the effeotlva energy baaed on

HVL for materlala ooamonly uaed for oonatruotion of loniseStlon ohanbera la gi-

yen In table 1. There la a difference up to 9% for theae apeetr*. Another uae-

ful parameter to knew la the ratio of m**e energy absorption ooefflolent for me-

dium and air. Table 2 ahoww tha ratio of//-#L^ M ^ weighted by the energy fluec-

oe for th*M apeotrm t</^#-)M! oeloulated from the effootlvo energies. There

Table I, Ratio ofmed maňme a

(apeotrum)/S (HVL)'.ir'

Table 2t Ratio of

apeotrum water , f*t bone

Table 3: Ratio of(^Si

i

2

3

med

apectrum

1

: 2

-"IT

}i

f

0

0

1

1.003

1.013

0.999

^ : : :

Li? ;

.992' 0

.9711 0

.010 j 1

i 1-r*Y.

035 :

089 1

t ^ ^ L(HVL)

:tFp

.964

.847

314

0.979

0.899

1.047

! CaSO i

t' 0.912 1

866

269

la quite good agreement ln the oaae of water but up to 10% difference in the ea-

ae of fat and bone. Thia differenoe in even higher for materials with higher Z

Ilk* for aoa* TL mat#řlala uaed to aMtaur* tha abaorbad doa* or tha effaotiv

energy baatd on the energy dependeno* of TL aignal for two dosemetera with 'f-

ferent Z. Differenoa up to 30% can be <sxp*ottd in the oaaa of Ca?2 "'a CaSO. a#

it ia aeen 1-i table 3. Tharefor*, it ia ueeful if not neoeaaary to know th* who-

le X-r*y apeotFua if we *ant to improve our aeaauratnenta in thia energy region.

Out of mothoda uaed to measure the X-ray apeotra two of them are the moat com-

mon. They ua* N*I oryataj or aemioonduotor aa a deteotor. Signala generated in

the deteotor are prooeaaed amd aa a reault we meaaure the pulae-height diatribu-

tion. Beoauae of different diatortiona during intaraotion of photona and during;

prooeaeing, photona with given energy *r* not fully counted in appropriate ohan-

nela but partly contribute into other ohannala depending on the Had of dlator-

tion ao the aeoond part of the whole taak ia the dtoonvolution of the true ap#o-

trum.

We have develope4 both ayatema baaad on oryatal aa wall aa aaaloonduotor de-

teotor. The ayatea with Nal oryatal o*n be uaed in aituattioaa when w* do not re-

quire high reaolution and in aituatlona when the uaa of the aeaioonduotoy d#teo-

tor ia teohnloally diffioult ot inpoaaibla. It h*a bean deaigned for ener^iew

leas than 100-150 k*V and will be uaed mainly for measurement* of aotttertd ra-

diations. Thia energy limitation met** that w* oan neglect distortion due to

Oomtpton eoattering. Thiokaasa of the orystsl 0.5' enables to negleet penwtyBtlem

of photons so there art only two kinds of distortion whiah hs-Y# to b* oonaldsrsd.

- 1 7 5 -

Thay ar^ tha raoapa of i/ end K^ photon* from lodina and d.tatortlon dua to tha

final raaolution of tha dataotor.

Wa hava uaad Ca-137, Oo-57, Am-241, Nu-152, and Pb-210 aouřoaa to aaaaura ra-

aolution of tha oryatal. Tha a:papimanta,l pointa in figura 2 oan ba fittad with

fonsul* R/ % - 171%!' /kaV ajsd thl< fonaula waa u#<d for oovrattiom of tha ft-

aal raaolutlon. Oorraotlon* for tha aaoa, a of K^ <md X^ photona froat iodin* wa!

so< 1—

. MU!

^' ]

1

?lg. 2:

Raaolution of Nal dataotor u*ad

in aíatam ^ r?lg. 3:

Raaponaa of Nal dateotor

oaj.ou3.atad with taaumptlon that thera waa only ona photon amitted with anargy 29

ka? whioh ia tha ma*n anargy for K^ and K/S photone from lodina. After all wa

davaloped a program for daak typa computer whioh oan oaloulata a raaponaa matrix

of N*I oryatal in thia anargy ragion.

Flg. 4:Spaotrum maaaurad with Nal dataotor

Figura 3 ahowa tha raaponaa of tho crystal fot

75 keV photona and tha ohanntl width 5 kaV aa oal-

oulatad by thla program. Daconvulation of apaotra

wara dona by 3ooffleld-Golda tfsohniqua /2/ with

i aa a maaaura of oonvarganoa. The apaotra obtainad

thla way wara further oorraotad for abaorbtlon In

tha air and tha antry window of tha dataotor. Tha

axparlmantal valuaa of tha pulaa-haight distribu-

tion and tha daoonvolutad apaotrum oan ba aaan in figura 4. Tha apaotrum i# for

Stabillpan maohina with TT 250 tuba, 1 m from tha targat, voltaga on tha tuba 60

kV, currant 10 mA, and inharant filtration 1.8 am AI. Tha auddan drop in tha an-

argy ragion around 37 kaV ia probably dua to largar amount of barium in tha gla*a

during manufacturing of tb* tuba and aubaaquant highar abaorbtion manufacturing

of tha tuba and aubaaquant highar tbaorbtlom In tha axlt window of tha tuba on

K-wdga of bajriuH.

- 176 -

K g . 6<

Speotru* measured wtth Oe(M) detec-

tor

?ig. 5'

FhotopaaJr affloianoy for Oe(Li) deteo-

tor aa maaaured with Eu-152 and theore-

tloally predicted

Our ayatem with the semiconductor detector is uaing the OeLl deteotor manufac-

tured at Nuolear Reaearch Inst., Řež near Prague. Thioicneaa of the dateotor ia

5.5 mm and diameter 9 mm. It a reeolution as apecified by manufacturer la 680 keV

for 60 kaV photona from amerioium.

The eystam h&a baen dealgned to meaaure primary X-ra.y baama from 10 to 300 keV.

In thla oaae one ha,a to ataploy all correotiona for distortion. Figure 5 ahowa the

depondenoe of the photopeaJc efflelenoy for our detector e.a theoretlotlly predioted

<md meaaurad with Eu-152 aouroe. TheoretiotLl prediction 1< bMted on Monte Carlo

ctloulationa done <tt Kurt R<3<#mait L*b., Chioago /3/. The obtained remits indicate

good agraamant between the trend of experimental values and theoretloal pyediotion.

This enables us to us* effectively also other results of theoretioal oaloulation

like the eaosp* and Compton fraction. The exact distribution of Comptoa continuum

for our detactor was not known ao we ueed a rectangular distribution with the are*

of rectangle equal to the Compton fraction for particular energy. The whole strip-

ping prooedure was done on a desk type oomputey. Plgure 6 shows the speotram of

Siemens*Monopan, 60 kT, 2 mA, and filtration 0.15 a* Cu as measured with otur se-

aloonductor deteotor.

Conclusions

Proa the data given here one oan see that there are situations when the use of

the effective energy based on HVL asasurttxent can result in large errors in snasu-

red cr talouleted absorbed doso. These errors depend on actual speetral distribu-

tion and are usually larger for the lightly filtered bem*. If we want to iaprove

our ssaiureménts or calculations ia this energy region we have to know the whole

siectnat. Tin knowledge of spectra is also important to the design of new diagnos-

- 177 -

t lo techniques. Thle paper wanted to show the extent of possible errors and how todesign an e f f i c i ent system for the measurement of epeotra.

References

1 . Johns, H.E. and Cunningham, J.R.I The Physios of Radiology, Charles C. Tho-mas Publ., Springfield 1983..

2 . Sooff ield, U.K. i Naval Radiologioal Defenoe Laboratory Report, USNRIJL - TP447 (1960).

3 . Chan, Heang-Ping, at a l . i InTestlgotlon of Baergj Responses of daraaaliu. andCorrection of Measured Speotra by Means of Mont* Carlo Simulation, Rad.Res. <-'(1984), 443.

- 179-

V. B I O Í C O I C A L P R O B L t M S I X R A D I O T H E R A P Y

V. B I O L O O I C K Ž P R O B L Í M T V R Á D I O T T R A P I I

HUMAN

7PCM RÁD^ATIOW EXPOSURE

J.M.Martin

University of Dundee,

Dundee, Scotland

The subject of my paper tit* a little oddly in the programs* of this m**ting

but it h"< been given a special relevance and poignancy in the aftermath of th<

Che mohyl arcident for the only event* which could conceivably lead to aeriou*

exposure of larg* number* of the population are a catastrophic accident to a lar-

ge nuclear installation or a nuclear war. In considering the conaaiuence* of

such evants three question* come to be answered:

1. Wh't level of brief whole body expo*urw will cause death? By brief ia Meant

withih a few minute*.

?. Wh't dose* can be fceepted for protracted exposure?

3. What are the long-term conssiuencea of exr*o*ur*a at the level* involved in

1/ and /2/?

While the nature of the rsdioactive emissions from an accident at a nuclear insta-

llation may vary and result ia whola-bady, *r, differing degree- of p*rti*l b*dy,

irradiation in the C M * *f a. nuoleajr w*apoc the gama* ray*, whether th* prtmpt

emlssian from the nuol*<ur flasian or tha d*la.y*d *mieaion from radioactive fall-out,

are beth anargetlo enough to lrrmdiat* all th* body** tla*u*< mor* or 1*** uniform-

ly. Following uniform whol* body axpoaur* th* m*.joy f*ot*r d*t*naining d**,th *r *ur-

vlval ia the damag* to th* h**a*top*l*tio tissue* *,ft*r whioh gut epithelium 1* th*

mo*t orltloal tissue.

Irrespective of whether the cauaitive agent is radiation or something else bio-

logical variation in susceptibility between individuals ie rharscteristic of all

living oryaniama. The answer to the firat question, therefore must be some avera-

ge v 'lue ar.-1 the one usually used is the dose th^t ia expected to kill half th*

itifMvi^nnIa exposed, the eo-c*lled LD50. The bf-aic circumstanrea of exposure which

we assume for an LD5O value are that the irradiated persona will be protected from

mechanice! injury, from any thermal radiation and from lesa penetrating kin<l* of

ionising radiation such *s neutrons and that therapy, if it wera to be availabl*

to all, would be limited to the simplest meaaurea for traating aymptom*. In auch

condition* ^ny de*ths which would occur within th* n*xt *ixty day* would reault

from severe dumage to haematopoietic tiasuaa *Bd b* uncomplicated by, fcr axampl*,

tissue necrosi* of skin 3r of limb*. Thara i* r*m*rk*bly little evidanc* on which

to base an eatimat* of th* LD5O in *uch eircumat*ne**.

In th* e*rly yeara of th* d*velopment of th* *tomic bomb th* American worker

Shields W*rr*n eatimat*a th* hum*n LD5O a* about 45OR. In 1974 Lu*hb*ugh propo-

sed a vřlu* of 450B and thi* v*.lu* i< r*p**t*d in th* U.S. Rational Council for

R*di*tion Protection Report Wo. 42 <l*o in 1974. Ho r*a.l *vid*nc* i* produced for

thi* v*lu* though in th* W.C.B.P. Report it i* **id to b* *th* m*4ian of a nuabtr

of edneatad gu*ase* mod* by * group of U.S. azpart* in 1949*. Th* *t*nd*rd U.S.

- 1 7 9 -

monograph, prepared by the U.j. Department of Defence entitled "The Fffects of

Nuclear Weapons" in the 19S0 and 19^7 editions vives values of 4^CP <,nd 4t/CP

reapp"tively w!-ile the revisions in 1964 *snd 19P0 ignore the matter completely.

Two American workers examining the Japanese ř-omb dFta rs'-ve, in 1956, a value of

7< -<' )'.

!n a report '' a s y m p o a i u m s p o n H o r e d hy the .i.i. N a t i o n a l ^'ommi'tee f or ťa d i a -

t i ^ n Mrr;tactt"t: tn 1'^Pl, a range of v a l u e t s i m i l a r !o the ab^ v e i^ pr'-pcsad ťy

're v a r i o u s s p e a k e r a . Hie c h a i r m a n of the relevant s e " p t o n s , T'r. V ť - t o r !cnd, c o n -

ctu d a d that. th<- v a j u a lay between )0C ar.d 35C r a d a .

In tritair. th.< s i x t h report of the "oval rumtnission on in v i r o n m e n t ^ l !' !h;tior

in l;i"*<i stated that ti-.e ] D 5 0 for tran waa 2"0 rptr,9. Th.ia e x c e e d i n g l y low v p l u e ia

baaed .!, a^c<s Amt-ricřn data or. leukaemia patienta. In a review in 1979 a froup

at !ha fat:.<nHl Mndiolopical Protection Board in f-ritain ;uote a figure of *^f

rede ar-* ir. their aubmiHaion to the en :uiry r'nremin^ !he aaftty of a P.W.P. for

our ;..i?e*dl site they yivp a value of 4CC r.da.

It; tE'ny of thfse repcrta it ia not clear whetřfr the v l u a ia exprâaed a< in

«ir, on the aurfare of the body, at the body mid-1 ina or at tone marrow. In the

arûtrfrt which follows, which in based or a etudy by our Mfîcal ř-esearrh Counr-1,

all the r*'aea h've been aanesa"d H^ ;cne mnrrow f*ppth.

Foaaibla aourcea of infnrm' M < n on ]U*0 for the human fre studies cr th" caeu*-!-

tiee of the .'^ppneae atomic weapon <*xploaions, persona e pr-[<ed in Mccident- and thoae

îvfn whole body radiotherapy. The doaimetry datM for J' p"rf-se t*nlt-aitna if even

no* uncertain end ie 'net more ř)f*ir;% reviewed. The studies ra-rie') ..sst fn 'h^Ke ex-

posed h"v? beer; corr«med prim'rily with m*-ktn^ doaa aatim-'fea ."or !he rurpfêa of

)on^ tern foltow up <<r so far no systematic attempt has řeen made to apply theaa

doaimetric studiea t" )he fragmentary and incomplete information about mortality

and survival in the î^-et few weeks after the bomb eirloaiona. Despite, therefore,

a nnmter of attempt* '<- ott<-in s me there i< no v l i d human data from thia source.

Following <<rty rw^t ston acci*1ent, particularly a major one, extensive studiea ar*

conducted m 'n attf-mpt to estimate the dceea received and, of course, there is c-ra-

ful titse^-vation "f 'Je individuals who have bean exposed, iiowever, be fmse the cir-

rutnatancea of r nt trr jor accidents involve cloae proximity to a radihtion source,

irr'di«tÍL't; of the tisauea of the body ia commonly non-uniform snd severe localised

tiaaue necrosis fie;uently occurs. For the purpose with which we are concurred all

cRsps have been excluied where tisaue necrosia and/or grossly non-uniform diatribu-

t ion of *<-He in bone marrow have been regarded at major factors in ''ptermininx a

iřth^l r.;ť-'i!!!e ^nd/or where specific and potent therapy wPS employed.

]f *?e *ses this, of 19 auch c a e a receiving more than 2t?C rsda, 9 hav* to be r<-

<<r-tf-<i. ^[!f of the 10 accepted caeea aurvived and 1 died. It is very 'oubtful if

trie death, which waa in the reactor accident at Vinca, was primarily iue to haema-

topoietic âmfpe. However, it is only by including thia death, which occurred in a

f-roup of people who h^d received around 350 rada, that we have any deatha at all

attributable to exposure ft thia level. Thia dat*, acanty as it ia, seems to he th-

sua total of the human evidence froa radiation accidenta which ia relevant to the

determination of an LD50 and it can do no mor* than auggeat atronply thst th* LD50

for man must be a pood deal above tha average doae recaived by the ten subjects

/ i 17 rads/.

Tha third potantial aourca of uaafu) information ia radAotharapy. Whola body ra-

Hotharany ia in uaa but normally for patlanta who ara f!aaparataly ill and the r<-

aulta ara of no valua in datarmining tha LD50 for normally fit individuala. Howaver,

whole body irradiation of ralativaly fit individuala, that ia paopla with no bona

marrow damage, h"a baan utiliaad in tha traatment of twing'* aareoma of bona with

- i80-

th« aim or atpriliairtR the undetectablp, small, distant metastcees coraidered to

be praaent when the primary is di-^nosed. Here there sr* reports of 20 young p*-

tienta who war? given t- mid-plane doae of 300 rada from a cobalt 60 source. The

dose waa homopenpoua to - 10% and waa given in 10 minutes. Of the 20 caaea 19 we-

ra of Kwin<? a* sarcoma and the other waa subsequently found to have leukaemia. Mo-

wever, all survived for at least ona year, that is well beyond the period when

death, dua to radiation exposure would have occurred. Theae observations on their

own indicate clearly that 300 rada average bon? m-rrow <1oa<< ia unlikely to kill

aiore than a email percentage of those exposed. The 90% upper Poiaaon limit of <e-

ro deaths in 20 au:.-ecta ia 15% Mortality.

When the radiotherapy and accident information ia combined no mortality ia found

in 2J subjects with doaes in haematopoietic tiaaue ir the ranê P50-10C rada an<!

ona death in 7 subjects with doses in the range 300-400 rada. This information ia

luite clearly inadequate on ita own to provide a numerical value for an LD50. Ho-

wever, the information, though scanty, giv*a reasonable ground for a .judgement

that the LD50 for a man ctnnot be much leas thHn 450 rada bone marrow doae.

Some support for thia judgement comee from atudiea on animala Rnd from the ob-

servation by Dr. Pobin Mole, now retired from Medical Research Council Badiobiolo-

ficil research Unit, thnt the alope of the cut-v* of probit mortality pâinat doae

ia closely similar in < ranê of lArper mMmn^jla. If we take the the one death in

four at over JOC rads, which waa the situation at the Vinca accident, piving a pro-

ability of 25% and extrapolate uain^ the 0.2 slope a value for the LD50 of 420

rada results. 'Ahen all the 30 cues for huaans are included, which meana that t*ia

mf,re rr-ciae doainetry available in the t-Hdiotherapy casea is utilised, a valu of

4S0 rada ia obtained for the LP50.

The <1osa killing virtually everyone /95%/ ia auggeated as 600 ruda, that ia 450

plua 150 rada correaponding to 450-150 * 300 rada which, as we have seen, wiJl kill

very few /5%/.

Studies by Ashton and Spiers relating the bone narrow dose to the doat at th*

skin surface for a human being omni-directionally irradiated with gamma raya over

a range of energies ahow that, for gatma raya of the energy concerned, a bona aa-

rrow dose of 450 rads corresponds to an expoaur* in air at the position of the bo-

dy surface of 600R. /Table 1/ Brief exposure means it haa been received within a

few ainutea.

Brief Exposure

Air P'*e

R

400

600

800

Brief Expoaurw

Mean Marrow

Dose

rada

300

450

600

Letr.'-lity

A few will dia

/approx. 5%/

Approx. 50% will di+

Moat will die

/approx. 95%/

All deaths will probably occur within 60 daya and certainly within 90 daya. The

paak of deatha would ba liktly to occur in 3rd, 4th or 5th waaka.

While ona must uae the figuraa with caution firat beeauaa the doaiaatry ia ba-

aed primarily on biological indicator-, tecondly bacau-a of the complication of

- 1 8 J L -

skin dnaaye by /3 rays nn<3 heat and thirdly becauae medical treatment waa <;iven in

moat CřKf-a, the figurea released in the Chernobyl nccident /Table 2/ art broadly con-

firmatory of the valuta in Tabla 1.

TABU Z

Mumber exposed

22

23

SI105

Deaths

19

7

/f< more unlikely ta

onrv ive/

Hone

Hone

] Dose Pan^e

! /Marrow/

^ 600 - 1600 rada

! 4 20 - Ď30 rada

200 - 4 00 rada

PO - 21C rada

Sinoa the 6 individuals exposed between 420-630 rada, whe are listed aa unlike-

ly to survive, had survived to ths data of the report, it is unlikely that their

deatha, if they eventuated, were due primarily to bone marrow damage.

What affect does supportive or apeeific treatment have? The t-onclusion from

ar, extensive review of a not very abundant or criticl literature was th'.t the

observations <1i<! not bear out expectations entl it would be fnir to Bay that ap*-

cific treatment may have value for an individual but has no appreciable effect on

the I.D'jC. f*<iir. this aeems broadly in line with auch information aa ia vailaHe

in the Chernobyl report.

The N C W Report Ho. 42, referred to earlier, eaya "Třere have been t;o known aur-

vivora 60 !<ya after a brief to'sl-body exposure to 65OR without Helical treatment*.

Thia ia an oft luoted atatempnt, which ia ttua but is nialendin^, because there ia

no record of any humnn receiving a brief whole-body exposure to 65OR of X or T raya

und net receiving treatment which ia quite a different matter!

Expceure at ).evls Below the LD50

Por brief exposure at levels up to and including the LD50 human reaponae has

a eeripa of patterns. At bone marrow ^oaee of leas than obout 75 rada injuriea are

a-e,ymptomatic ard the fact of exposure can only be detected in retrospect by blood

ce?! counts or observations on chromosomes. Such procedures would b* availnhle fo-

llowing an accident to a nuclear installation but are hiphly unlikely to be so in

the course of a major war. At higher doaes there are symptoHa and the acute radia-

tion ayn-*rome becomes appsrent. This hfs three phases.

1. Prodromal Phf-se

The eymptoma include nauaet and vomiting and somatiasa apathy. Mauaea and vo-

miting occur within an hour or two and nay last up to three daya.

2. The Asymptomatic Phaae or Latent Period

Thia cay last up to twenty days. Although the parson is asymptomatic during

this latent period, changes are occuring in the body which will be followed later

by manifest illnesa. The patient will feel quita well during this period and can

go back to normal activities,

j. Incapacitution

Bone marrow damage becomes manifest by lneapaeitation and specific lllneaa.

The aeverity of this is proportional to the dose and it may be transient or can

laat up to sight weaka in those who survive.

Over t|;p neit rHnge of doses up to the LD5C, lliflnr 1 -.rd Phase 3 syapto»s o-crur with increasing severity ee the doae r i se* . Table 3.

Brief Bxposure Mean BoneMarrow Dose

rads

L_

up to100 -

40C

150200

up75

250

300350

to 75- 200

rareabsent to

moderate

mild to

severe

severe

severe

Severity of Symptoms

raremild

At doses above the LD50 value the Intent period may be a week or l ess and atexfonures wfccve, eny, 650 reds i t msy «rell be absent. At the lo*er end of thi»run?* the c l in i ca l e f fec t s of bone narrow coinage wi l l be the more important, buteoove V,'O reds dam'. e to the gaatro- intest inal tract dominates end that to th«snnl l intest ine has • major influence on immediate ab i l i ty to survive. Cell pro-duction ir. >he crypta ia loat and th« v i l l l become bare. Thle leada to dlnrrhoeawith greet riuid loos , failure of food absorption, and bacterial invasion. Pe-covi-ry is lulrk, ir. about a w»#k, i f the patient can be kept al ive by fluid ande ler tro ly to r«i lecenent, but, of c o u n t , eecondary e f fec t s due to bone nurrow da-mage will f o\ 1 ow.

At dose leve ls in excese of 1 ,COC rtfla there ia immediate nausea, e*plosivediarrhoea, symptoms of shork with dieorientation pnd death will occur within afew 1 ours to a day or two.

}'ro'. rartad Exposure

When radiation exposure i s protracted the body exhibits an ubi l i ty 10 recoverso that the dose reiutred to k i l l increases profreseively with increase in ove-rfill t in* . There are two st««es in recovery with very different time relat ion-

If w» tike a ^roup of c a l l s and irradiate than with X or ftatnma raya and thenrurvy <nii • [iroraaa which en"tlea \is to determfna ihrae which survive und are ca-f*t-le of reproduction, we frtl a curve a\irh aa that in Kif?. 1. The presence of theshoulder on the curve implies that dam'fre haa to be accumulated before the inac l i -vation occurs so there i s a poes ibi l i ty of recovery from thia Injury. Thia i» d«-mor.strated in PIR. 2 which ahowa that, i f on* atope tlie irradiation and pivea thec e l l s p. rest of some hours before applying a second dose of radiation, then thedose required to produce the same level of damage in two f-actiona Is greater bya ounntity D'i than i f the radiation ie given in one doaa '>nd thia ia a n i a u r *of the lntrarel lular repair which h«e taken place.

The f irs t etn^e of recovery, lntracal lular repair, or Klklnd repair aa It laoften e»}l»d, la re lat ive ly faat and 1« capable of Bjakinn food the aub-lethaleffeota of up to 1)0 reda of total doae when thia ia received over a nuaber ofhours. It haa a half-tiaie of 2-J hour* and whan eo»pleted, the proeeee returnathe rfidioresistanee of theae c e l l s to i t * original l e v e l .

- 1 B 3 -

'vivmj Friction Survivinf Fracuon

Fig. 1 Tig. 2

i

The second stage of recovery is a much alower process, based on division ofsurviving ce l l s , and it ia capable of increasing tolerance to the lethal actionof radiation on the whole organism at the rate of at least 10 rads per day.

The procesa can be understood aa followsand is illustrated in Fig. 3. If we placea group of cella in a veasel with culturemedium, and the cella divide every 12 houra,the number preeent will grow exponentiallywith time. Pollowing a dose of radiation/say 300 rsde/ no changa will be seen untilafter more than 12 houra for It ia only whenthe •lemt.nda of dividing are undergone /per-haps more then once/ thPt the radiation da-mage will be apparent. The cells will stopdividing and so the number of cel ls presentceases to increase. Those cells not "killed1*by the radiation trill have gone on dividingand eventually they produce a growth in thenumber of cella at, of course, the same ra-te m hitherto.

The result of this behaviour on tlie via-bility of a system is illustrated In rip. 4.Consider first a tiaaue consisting entire-

Fig. 3 ly of proliferative cells of number N wesea, /Fig. 4a/ that, following irradiation,

the surviving proportion ia reduced to S, ssy 10'*. The survivors will reprodu-ce at a rate Inversely proportional to their cell cycle time while st the sametiae damaged cella are being removed by normal procesaee. In this figure the aur-vival rate and repopulation rate are taken as the esme and a critical reductionin alee of the ayatea la aeen where the loaa and growth curves cross / ' / .

However, a eystea will normally consist of, at leaat, proliferating cella /(,/bnd differentiated cells /N/ i . e . thoaa that h«ve developed to carry out a spe-cific function in the body. Theaa latter cells are inaenaitive to radiation andthe critical reduction in organ sire following irradiation will depend on thel i f e tiae of the differentiated cells ' nd the rate of repopul«tion from the stea

1441 1*0Hour .

- 184 -

coapartaent.

Fig. 4a Fig. 4b

The result of this behaviour on the viability of a system ie illustrated in

Fig. 4. Consider first a tissue consisting entirely of proliferetiv* call* of

number n we see, /Fig. 4a/ tnat, following irradiation, the surviving proportion

is reduced to S, say 10~ . The survivor* will reproduce at a rate inversely pro-

portional to their cell cycle tiae while at the same tia* damaged cells are being

removed by normal processes. In this figure the survival rats and repopulatlon

rate are taken mm tha aame and a critical

reduction in sire of ths system is seen

where the loss and growth curves crosaA' /.

However, a system will normally consist

oT, at least, proliferating calls /{••>/ and

differentiated cells /V/ i.e. thoae that

have developed to carry out a specific

function in the body. These latter calls

are insensitive to radiation and the criti-

cal reduction in organ size following irra-

diation will depend on the life time of the

differentiated cells and the rat« of reps- -

pulation from the stea cell coapartasnt.

tale

of (all

Fig. 4c

In the second figure Mb/ is shown the effect when the differentiated cells

have a long life tiae /aa is the case in the liver/. Little change in the total

cell population results. However in the following figurs /4c/ it c*>n be seen that,

where the life-time of the differentiated cells is short, f or example, as in the

intestinal epithelium, the total of cells in the organ responds rapidly to s de-

crease in the stem cell nuuber. Clesrly if the reduction of cells in organ is too

great the system will be unable to perform its function snd death of the depen-

dant aninal will usually result.

When the stem cells recognise that they hsvs been injursd they may speed up

their production rate either by shortening their cycle tias, froa 5> dsys to 1

dsy, '<s in skin, or by introducing extra amplifying divisions between the atea

call and the differentiated cell compartmente as in marrow. The differentiatod

calls, however, proceed through their comp&rtnent regardless of irradiation.

They don't divide so they don't die - like old soldlera they only fade /wear/

bwuyl

An illustration of the blood picture /Fig. 5/ following irradiation at doses

below and above the LD50 velua is given in the next slide. If marrow is complete-

ly depressed following a lerge dose of radiation,all types of cells :.n periphe-

ral blood will decrease in number the rate of decrease being related to the life-

\

span of each cell type in circulation. For redce l l s , the oxygen carrier*, the life-span is120 days, for platelets /coagulation/ l i f e -span is about 6 flays and for neutrophlls / in-geat bacteria/ 4 days.

In the first diagram there is l i t t l e changein the red cell count as would be expectedfron the long red cell l ife-tine but neutro-phils fe l l quickly, em do the platelets. Un-like other cel ls , lymphocytes are sensitive!to radiation at all stages and they show snimmediate fa l l . They are slow to recover innumber. Recovery in tho blood picture is evi-dent in the first case but, following an obor-tive attempt, rot in the second.

Now how do these two recovery Mchaniaus of intracelluler repair and cellulerrepopulationp mhich we have loaked at in isolation, translate to the intact ma-mmal? Figa 6<§ 7 illustrate the behaviour in mice.

U

11')

211 28

dtyi

Fig. 5

>; - UX> t»dt

1 1 - 4 III.UII

»> JOHi.u.i

fig. 6 Pig. 7

If a group of nice ia given a brief whole body expoeure D. of aay 550 rads,

of itself not lethal, then at t'O the additional dose required to produce 50%

lethality /600 rada for this specie* for a brief exposure/ is 250 rads. However,

if the second increment of dose ia delayed for a period of 4 houra the increnent

of dose required to produce 50% lethality increeaae, in thia caae by about 150

rrda /Tin- 6/. Moreover if & D, of eay, 300 rada ia given and then ia followed

by a D 2 of 300 rtde 4 houra later a curve of increased resistance with time is

found similar to that found after D^ /Fig. 7A In other words recovery after Dj

was unaffected by the experience of recovery after D^ which is exactly the res-

ponse which would be predicted us a result of Elkind repair.

Other similar experiments show that, after a longer period of time and follo-

wing a dose sufficient to initiate cellular repepulation i.e. some 250-300 rads

in this species, them is a continuing increase in radiation resistance of about

30 rade per day between 1 and 9 days.

For determining probability of death from protracted exposure this two stage

response is expressed in terns of the so-called "operational equivalent doee,

OED": the formula is as follows:

- 18* -

OED • B - 200 - 151 /surface exposure - R/

OED » D - 150 - lot /bone marrow dose - rsds/

Thus if • group of people received 700 rade spread over 10 days the OKD • 450

which is the brie/ exposure LD50 so 700 rads received over 10 days would produce

a 50* lethality.

These equations can be apllied whether th« radiation is continuous or inter-

mittent. There i.; an upper limit for the value of t taken to be 100 days. This

limit is aet on the baeie that the total exposure is rising to a level where the-

re is a substantial risk of the induction of cancer. There ia also sone evidence,

from laboratory studies, of death in the more sensitive animals, due to bone ma-

rrow exhaustion, above about 1500 reds.

Now will these recovery pattern* exhibited by tha mouse apply to man?

Human exposure d*ta under such regimes is, of course, extremely sparae but a

detailed analyaia of an accident in Mexico with a rsdiation source, involving pro-

tracted exposures of humane, has bean made. It shows good agreement with the O.l.D.

formula /Table 4/. It is important to rota that the formula was proposed before

the accident data became available.

Person

SonOr" nd mother

Mother

Daughter

father

Mean Harrow Dost

rads

4060

2360

2470

1620

1350

Time

24 days

90 days

115 days

99 daya

106 days

Outcome

died

diel

died

died

survived

Efft£i£

What now are th* consequences of radiation exposure for those who survive?

A smnU proportion of the most heavily irradiated survivors, th't ia above

about 3Of.}>, could be expected to have cataract after a few years. Experience in

the Japanese exploeiona Indicates that the number would be very small.

Subaf tial depression of the aperma count in some three to six months would

b« caused by an exposure greater than about 20P and, for doses up to about 60H,

raturn to normal count would be slow, taking a year or two.

Older women exposed at around the LD50 value might have a premature menopause

but otherwise female fertility would be unaffected. One of the women in an acci-

dent in Algeria, and who received a marrow dose of around 1300 rads, was pregnant

at the time. She aborted but became pregnfint again a year later.

For cataract, infertility and of couraa mortality there ia a threehold dose b»-

low which the affect will not t* Men but auch i» net tha caae for the induction

of malignant disease or for call mutation in the germ line.

Table 5 shows the probability factor* tor induction of malignancy for varlaue

tiaeoea given in ICBP Report Wo. 26. Th* overall rate of 125 camaa par 10 par

rafl would repreeent about 5* of the aurriTora of an LD50 exposure. This amounU to

an incrwaae of some 25-30* above natural frequency.

- 187-

TABU 5

Tissue

Breast

Red bone

Lung

Thyroid

Bone

All other

Risk Factor*

Marrow

for Varioue Tieaues

Deaths par 10 nsn rads

252020

55

5°25

For induced solid cancers there is a latent period of at least 20 years befo-

re manifestation. The peak frequency would be between 20 and 40 years later so

that many who had been exposed would die before this effect of exposure was evi-

dent. About a quarter of all the cases induced would be leukaemia the peak inci-

dence of which comes some 7 years after exposure.

In the context of a nuclear war und because of this delay between exposure and

onset of symptoms, it follows that most of the cancera induced would occur when

eny national reconstruction would be well underway. There is no impairment of phy-

sical Bnd ment«l qualities during the latent interval and, looked at from a deta-

ched standpoint, the national loss would be tolerable.

M«ny societies have continued to exist with a higher death rate of younger a-

dulta from tuberculosis nnd malaria.

From the Japanese data there is evidence that dose >20 reds will cause mal-

formations and mental retardetion in children exposed in utero up to 18 weeks of

pregnancy. When account is taken of the fraction of the population likely to be

involved the contribution to the totality of effects is small.

As far ae hereditary damage is concerned, obviously thor- • too old to become

parents after the exposure cannot be responsible for any hereditary damage. For

the others, about half of the total of all the hereditary damage produced by the

radiation would be seen in the first two generations of the descendants. Oeneti-

c*lly determined visible handicaps have an induction rete per red of Bueh the sa-

me value *e for malignant diseases and for survivors of reproductive ape receiving

an LDt>0 doae a few per cent of their descendants might be expected to show radia-

tion induced handicaps. /The ICRP 26 value of 40 per 10 man rads takes account

of only the first two generations, in which about half the damage would be expree-

sed, nnd then allows for the fact that exposure takes place over a reproductive

life of JO years in fa life span of 75 years/. The current birth rate of handicap-

ped children in Britain from all causes is between 5 »nd 10*.

Hereditary damage, therefore, following a nuclear war and assessed again fro«

a disinterested standpoint, would also b« tolerable. In fact no such damage haa

been aatabliahed in the families of tens of thousands of irradiated survivors of

Hiroshima and Nagasaki and over a generation has now elapsed since these events.

- let -

CUMULATIVE EFFECT IS FRACTIOHATIOB

AffD THE CHOICB Og RADIOTHERAPEOTICAI. TREATMKHT SCHEMES

K.Prokai , U.LolcaJi5«k, L.Judaa

Radiotherapy balonga to one of the prlnolpal toola In oan«*r oontrol. Both phy-

•ioiana and phyaiolata are reaponelble for approprlats usa of radiotherapy f«o Ill-

ties. Ae to the phyaiolata their primary duty oonalata In ascertaining optimum do-

•a distribution In the whole Irradiated area. They are responsible for donlmatrlo

prooedures, monitoring radiation beans, teahniotl preparation of treatment pinna,

fixation and localisation of th« patients during Irradiation, adaptation of doaa

distribution to speolal requirements ato. This should not ba, however, their sing-

le oonoern. They should ahar« th« full responsibility with physicians also for

improving radiation approaches aa to the time distribution of applied doaa. That

•sans they shoulft contribute alao to looking for optlmua adaptation of fraotlona-

tlon aohemes to individual tumour types and locations. Suoh a responsibility seeaa

to be shared by pnyslolata at a few radiotherapy departments, only. At the most

departments suoh dutiaa remain atill outalda their lntereat. Be would Ilka to to~

oua our attention Just to this region sinoe a lot oan be done Just by radiologi-

es al physioieta.

For many yeara all type* of malignant disaaaea had been treated aocording to

a uniform schema, i.e. 5 fraotiona In a weak. From this point of view soae of the

malignant tumours were regarded aa radloreaiatant and others aa radlosensitira.

However, suoh a oharaoterlatlo is olosely related to the applied fraotlonatlon

sohnme. Ae oould oome to Important modifications of our points of view If the in-

fluence of the time distribution of dose waa better understood.

A now way aiming to thin goal waa started some years ago when the so oalled

N.'il; oonrept «ra« proposed. This concept was widely used by physiolana in estimating

tin nuiuuilvi effect !n fractionated irradiation. It was often used outside the

nrlmi <•{ lt« «['|'Ho«b]]) ty, whloh resulted In a series of treatiaent fnllures.

141 the 1 ttiar 1 and due to similar attempts different fraotloiiatlon aohemes began

to be used giving in some apeolal oases better treatment results than the earlier

uniform *ch<t-nea. However, to make an optimum oholoe ot fraotlonatlon soharae In an

individual case It is neoesaary to understand the whole radloblologlaal mechanism

In both tiftsues and cells to greater details. This neoeaalty la strengthened by the

faot that radiotherapy Is very often applied simultaneously with oytontaxlos, ra-

dlosennl t! zers, hvpertermla eto.

As tu the mechanlam In Individual oells one oan distinguish three phases run*

nlng one nfter another:

- physical energy la transferred to a blologloal objeotj radloal olustera are

foraod null some primary damages oan be formed too>

- ;>hy«lcooh«raloal radlokls reoomblne and diffuse but Interact alao with lapor*

tant blomoleculea - a great deal of primary damages are formed)

- b)olo£loal damages of blomoleoulee are being repnlredj unrepaired damages oan

lead to cell inaotlvatlon.

The two last phases oan be strongly influenoed If eome speolal ohaoloal agenta

are preaent in a given oell.

However, It seens impossible to desorlbe suffloiently all important oharaote-

rlatloa of lnaotlvatlon maohanlaa without the help ot rather oomp1leatad mathema-

tloal models. For dosaa and doaa ratss ooeaionly uaed in radiotherapy auoh aodala

can b« rather slajpllfled aa the flrat two phaaea are strongly related to the Ioni-

sing properties of Individual partlolee only. The primary dauages ar.-a fomed In

laaa then 10"^ seo After ptrtlole impaot aad there la not any oooperavtlve effeet

- 16* -

of different partiole*.Collective affeot of all partioles having bit on* o i l plays an Important role

1B the third blologloal phase only, te bar* proposed a obalc of models rteoo'lblngindividual ph«ee* and enabling to past from baalo characteristics of IndividualIonising particle* responsible for the first two phases to the global effect de-termining the result of the blologloal phase. The role of different ohemlc a-genta especially in the eeoond phase oan be also Included. Suoh models oar. • elpIn better anderatanding of radiation effeot for different kinds of radiations.The resulting effeot oan be oharaoterized by the ohape* of the surrlval ourritobtained under different conditions.

In fractionated Irradiation the lnaotiration effeots of Individual ooces arethen oombinod with the opposite effeot of proliferation prooessea. The alreadymentioned NSD oonoept and the modal proposed bj Cohen are the beat known modelsof eumulatlv* effeot. The former no del is purelj phenomenologloalj It la baaedon son* unjustified a-prlorl assumptions and It does not give any possibility toexpress the cumulative effeot In a scsl* being related to ratio of oells survivingat the end of a fraotlonatlon oourse., Suoh a possibility Is included In Cohen'smodel. Its dieadvantage seems to consist in some oharaoterlstios relating oell ln-tctlvatlon with proliferation prooesses. Any delay between starting points of pro-liferation and the applications of individual dose* Is not oonsldered and oan behardly included without a substantial ohange of Its baalo structure.

All then* features oan be Involved in the aeal-phenom<>nologloal model derivedby a generalisation of the BSD oonoept. The survival at the end of a fraotlonatlonoouras i s given byS /N,D,T/ - e~° where C - H.h/d/.f/t,T/j d - D/H, t - T/H.

The funotlon h/d/ represents the survival curve of a single dose in semilogarithmiescale. Cue to the fact that the iso-effeot graphs In log-log soala are linear (atleast approximately) i t Is suitable to express It in the Hugget parametrlsatlonh/d/ r « d . Th* function f/t ,T/ Is a factor expressing the Influeno* of proli-feration processes. In the region of linear and parallel Stranquiat graphs It oanbe approximated by f/T,t/ • * t" ' . T~ { the slop* of Strandquiat graphs i s thengiven by ^ • ( "* ~l)/r + f IT. k more complicated behaviour can be easily Inclu-ded i f Is not regarded as constant (e.g. It oan exhibit an additional T dependen-ce) . The formula gives, therefore, a »Tinoipal possibility to analyse scue moreoomplex features of oumulatlve effect without any a-prlori limiting oondltions.

Soae consequenoss exploitable la clinloal radiotherapy oan be derived from sucha Model. I would like to mention now on* of suoh possibi l i t ies .

Let us oonsider two different fraotlonatlon sohemes with the sane total tin* T.To obtain th* same *ff*ot i t must hold Sx.i[ .tj'13 - Ng.d^.t^ or dj/dj - x • '* J>/?~-- x V ^ where x - •g/Hi " *i^*2* T h # *-PP»>zljiatlon whioh was used Is fully entit-led as oan be neglected la oomp rison to one. The ratios of the correspondingfraction doses for different, values of x and ?~ar* giv*n In tab. l . The value ofV in the middle ooluan corresponds aooordlng to the NSD concept approximatelyto the skin or oonnectlve tissue. It Is obvious that for *> hypoxle tumour tissuei . e . for a swiller value of ?~ws oan r*aoh the saae effeet with smaller fractiondoses i f shorter tlaa intervals are used. That Is In aooordanoe with Fletoher'sdata as every-daj lrxndlation of greater massive tumours was more effeotlve la oosi-parieon with lrrs.dle.tloB every other day. If the shoulder on the survive! curve,i . e . th* parameter $*' , i s greater, th* hyperfre.otlona.tlon should bs useful. Malig-nant •elanoaa mells o«n sarr* as an *x*sipl*. Their survival ourv* obtained ln-vltro•re characterised by ^ - 1 , 9 5 end of* 0,1 [?J~ ']• 3*v*rmJ fraetlons la one weekintervals should gire batter results then oonventlooal treatment (5 fractions la aweek). SOBM nweat radlothampeutloal results see* to b* la agreeeMnt with deduo-

- 1 9 0 -

tioD fcllrwíng from the given model.

The mu *«1 can be used of oourse alao in ocnslderatlon oocoeming the doses need-

ed to *rft'icat* tumours of different volumes also.

A MrrH')^ ? 'H RADIATION TREATMENT

Ai-Í KKSUL1.; ť ITS AH-LICATION ON 228 PATIENTS

V.;.tttdov*. M.íantohew, Z.Naumova, V.Miltohev,

!rmS1tute < f no'logy At the Med. Academy, 3'fiA, Hulgari*

Radiotherapy has proved to b* the only mpthid for radloňl treatment cf ma^lg-

n^nt nanopharyngeal tumoura /1,2/. That Is why In the fnco^glcn) Institute ia

'J. la ainr- nor^ than 15 years auoh Attentit-n ...<n hocn payed t- the ioprovaaant

of Lh<? lrrs'iHtl^r. tRchnique applied in the tr«str..nt ;f thia tAmo' r site.

'< - .m,!?!" Ts!h.;d for treatment of thf rtm'try t na.i;tr atailtaj.e^ualy with tha

re^ :.ii lym -tatl-í-, situated in the retroyhary;.^-.) region and bilaterally in

th*- «)< it!w<i tc the supr*olavl.oul*r area tUg, 1), has beer first Established

Fig. 2=

Irraf<tif,jT of the naao- and retrophayyn-

(teal area with four ganuaa ray

i'ho . <t !!.'."« ^f thf tarr'* volume

It. :<i" f. <ntal eeotlon ťf the head

ir. <ir t-.-ae'.ice in 1^'7, usln^ the Siemant X-re\y atmulator a# a, lcoeJ.iKtng devio*

a.<: the nobndt m.lt ";smmatron-3" for irradiation /7/. At thia wtag# of the techni-

oaj equipping of our Radiotherapy Department, in order tc reach the rmther high

curative dose of 60 up to 70 ?y in the naeopatryni and the regional lympnatioa

without dmnti- ing th* orgina at risk, the irradiation teoimlqu* ahonn on fig. Z

an! 5 kl#ft! was applied. Tha ahort^omlnge of thla teohnlque ajre an inhibition to

give the curative dose right up to the b*ae of the akull, thuz requiring n*o*aa*rUy

a bcoet doee in the superior part of the target rolusM given ay braehytharamy

- 191 -

nlquaa /5/, as wall aa th* impossibility to apply It In treatment of advanoed et-

• «o where the tuaour haa already spread Into the base of the Jlcull and/or epheno-

ldel oavlty, or h»a lnraded the retrobulbar structures or the nasal and peranaaal

oavlties.

These shortoomlnga hare been removed coae three years later, after a 42 M»V

Sleatne Betatron had been Installed, lafclng adrantage of the 5 om deep altuated

a&xlnua of the ooee distribution of the 43 MV I-raj beams, it became feasible to

reaoh the ouratlve dose in the D U O - and retropharyngeel region* by two oppoee*

beaaa only (Fig. 3), without oauslog trrereraible damages to the t»mr"rn aanfliTm

rig. 3»Irradiation of the naao- and retropha-ryngeal area wtth two opposed 43 MVX-ray beams.

Irradiation of naaopharyngeal tuaouraspread In the nasal and paranaaal oa-r l t i e s by two X-ray and cma electronbean.

lar Joints. The omission of the paranasal pottala and the quit* narrow penuabraof the high energy I-ray beaaa mad* It possible, without exceeding the tolerano*dose of e Oj f .- the eye lenses, to aet the upper edge of the treatment voluae aahigh aa ollnloally neoeseary and to broaden the width ef this volume to lnoluaethe retrobulbar etruoturea when they are lavolred by the tumour. Furtheroore themuooeal reaotion la than limited in the target roluae only. Instead to be spreadIn the whole oral oarlty.

The problem to treat the o&aea with the tumour apread into the naaal and para-nasal cavities haa been solved by addition of an anterlo-posterior elaotron beeji,applied through a tissue-equivalent bolu* with embeded lead aoreens orer th« eyee/ 3 / (Fig. 4) .

The treatment technique of the neok lynph nodea has not bees basically changed.I . e . they are irradiated by two approximately oppoaed beans of oobalt-60 gaana-rays on eaoh side, aa It la shown on the left hand aid* *f f ig. 5. The only dlf-fei-enoe la, that i f after a mlnlaua target doae of 40 ay no metastatlo lymph nodesare observable by palpation and the oross-saotlon of th* neok haa shrinked to Itsaosaal s i t e , then the reaainlns 20 or 30 Oy to ooapl*t* the ouratlv* doae s givenwith eleotrona (fig. 5 - right). This way an about 30% re duo t Ion of tb* do?* latb* spinal ooid i s •ohlered,

A problea s t i l l l*ft open 1* tb* aoourate doso planning In the transition ton*between tb* head-part and tb* two neok-part* of tb* target volume, where tb* pe-numbraa of th* X-ray D**M overlap tbos* of th* gswa-beaat*. Prelialnar? dose oal-oulatlona gar* I t , that la order to avoid aubdoaag* in th* transition son* at a l -

- 192 -

Fig. 5i

Zrradlatiaa of the n»ok lymphatics by two

g*ame-rey beam* (left side) and twc gam»s

x*j beams up to 40 Oy plus 20 0y siren witli

eleetrons (rlglit aid*).

timum overdosage In the hot spots, ths distance between the two planes, 1B whloh

ths geometrloal edges; of the adjooent entrance field* lie, has to b» 1 cm. This

distance has been aooepted la praotloo whan th» anatomo-topographloal tad doei-

metrloal treatment planning 1* dona, presuming that these two planaa arc parallel.

When irradiating ths anterior n«ok fields however. In ordsr to fat aooees lo th*

uppar naok lyaph no (las at minima tlasua exosss, tha patlanta haad la daflaatad

backwards what lnoraaaas tha uapradiotabllity of tha does distribution In tha

transition cona«

To pet an impression about tha rarlatlons of tha dosa In tha transition sons

at raal conditions, dosa n«*aur«m«nts In a daaJ body hara baan oarrlad out. On

tba purposa onthatars with tharmoluninasoanoa doiacatara h«C baan lntroduoad In

both tha Internal Jugular valna, an othar pnlr of auoh oathatant had baan flzad

auboutaneouslj along tha stamo-olsldoHnastoldal rausolae, and ona oathatar had

baan lnaartad through tha ooclpltal foranan into tha rartsbral oanal. Furthar

tha anatomotopographioal data and traataint planning, and tha Irradiation

of the dead body was oarrlad out in tha sa»a way aa if It would hac baan a raal

patient with nasopharyngeal tumour.

This azparlment rarealad that tha width of the transition sons Is about 2.5

on. In It the neasurad dosa in tha oathetars showed that th* regional lyispbatio

chain deviates fron the nlnlmua target dosa by +10 up to +35!*. Along tha cathe-

ter, representing the spinal oord, tha measured doae Is 45^ of tha alned stlnlsna«

.argnt dose In the whole neck segment, rises up to 50% In tha transition lone,

and fells steeply down to 115 upwards.

Th* same experiment has been used for verification of tha dosa planning out-

side the transition eons, tor what dosametera hare baan fixed at different poluta

In the head-part of tha target rolume as wall. The comparison of ths measured

dose Talues with tha corresponding oomputed values showed differences which do

not azoaed 7% tor tha points irradiated by tha X-rays only and 6% In those Irra-

diated by the gaona-rays only.

So, fro* a dosinetrioal point of view, the treatment nethod described Is safe

enough to ensure tha prescribed minimum absorbed dosa In tha entire target volu-

me. This dosa oan ba sat t« high as 70 Oy without exceeding tha toleranoe dose

for the spinal oord, whloh In our practice la set oa 35 Qy.

This conclusion Is confirmed cllnloally as wall as by tha survival rat* of 228

treated patients, 92* of whoa ware In stages II1-1V of tha disease. Their relati-

ve oumulatlve survival rate, evaluated aooordlng to the aotuarlal method /4,6/,

Is 76* five years after treatment, and 55% even 15 years after treatment (Wg. 6 ) .

All the 19 patlanta la stage I and II were reovirrent free alive five year* after

- 193-

?ig. 6:Ctmulatlva eurvlvat rate of 228treated patienta: 1. relativ* (ao-lid lin*), 2. obaervad (daahed li-

na,'.

treatment.Nona of tha treated patienta exhibited ayaptotM of radiation induočd damages

of tha apinal oord, but eoma 30% of thtm had leat hearing M 4 lata harmful af-faot. Complioationa, whioh oould b# qutliflad a.# aooaptabla, a.ra the moat muooal-tia and aoma atlffnata of tha tamporo-manílbMlar joimta.

Ftefereaoea

1. Baduhn, D. at el., Best**hlungsmethodan zur Bab^ndlung Yon EplphMynxtmM-ran nit Kobalt-60 QaamaatrAhlan. lat Tumoram dař MundhCMa, daa H&chen* und áaaKahlkopfaa. Urban Sohwarsanbarg, 1969, 164-169.

2. Flatohay, 0., R. Million, Naaopharym. Int Textbook of Radiotherapy, Laařabigar, Philadelphia, 1975, 286-311.

3. Gantohww, M., V.Pandova, Aktual.klim.Onkol. 1963, 4, 111-114.4. Miltohav, V., A.SahatohiaY, Coaputar program for oaloulation of relativa

cumulative aurvival yataa of patient* with malignant neoplasms. In: Problewl naonoologijata, ÍÍ, 1993, 101-106 (in Bulgarian).

5. Momshmov, M., D.Dobrar, Qakolog. i^,1975, 1, 34-38 (In Bulgarian).6. Norveglan Cano+r Soolaty, Tha Canoay registry of Norway! Survival of oanoer

patients. Norw. Canoar Soo., Oslo, 1975.7. Sahatohisv, A., M.Qantohww, Z.Naumova, CDjubaliar, Nxaminatlon sf tha doss

distribution from t<l*s*mm*th*r*py of ths splphMyntMl eanear. Int I. Tat. Coagr.of Oto-rhlmo-lMyn#olOKi<ts in Bulgaria, 1966. O H I , Nofl*, Í970, 98-103 (In Bul-garian).

- 194 -

COKIEHTSOBliAH St;

II. :;ympoelua of Radlologioal Physlclste with International Partici-pation. I I . tympozlua kllnlckyob rndlofyslkoy a mei£ln4rodnou u-faatou (v.L»ginoTi).. 3

I . Treatqant Planning. I.Pl&noTanâ rddloterapla 7

The Influence of Patient Size and Shape on Absolute CT-aunbere forMfferant Scanner Oyetena (K.A.Jeneen and J . Joi-g^naen; . . . . . . . . . . . . . 7

OT-baacrt Treatment Planning Syateoa for Conraodore- 4 Home-Computer

T.Trner) 11

Topoiie-. :j ai.d Lose Planning In Tele gamma therapy of the Proatatlo Carol-noma ^V.Vlltchav, L. Alexandrova, U.L'ounharor; 1?

Computer I'.-cgrara for Physical and Rndlcblol. gic«l Calculations of theTrent men'. Plan* In Complex Radiotherapy of ~arolnooaa of the Uterine

i'.uatula, E.Putdfi, J.RexoTa, U.BrliAAlceva, U.Klvana, A.Katar).. . . 1*5•ur.Kovych avazM pro plînevAoi I6t^bj t.ir*nia. A Fenoll-Baaa Model

for Radiotherapy Tr«ata«nt Planning (J.Vech, J.Potaeell) 19I'rogran fr.r ftadlotherapy Treatment Planning. Progran pro slinaranf KCby

zrif*ri'ni ;J.Potmeeil, J.Vaah) 26Optimaliza'.ion of Radiotherapy In Ca mama* (O.Raaovak^, A.Kalfr, V.Krye-

tcf, r. .Kudll^kovS, .!. Peclna) . . 29

Our .iperlencea with Frachytherapy Treataent Planning (B.Plejko, V.lagi-nov4, J.K/illay, r.K#der, G.y.rillk) 31

Complex Loae Planning on IBM Compatible PC (E.Katona, l.Polgar, P.Za-raxii; 33

21. Cllnlca], I'oalmetry. II.Klinlc'Ka dotlmotria 37

Total :;kln Electron Therapy: Teohnlque and Coslmetry IC.J.Karzaaxk). . . . . . . . . 37(omparlnon of Iaodose Charte for Cobalt-60 Tele therapy Unit "Recua"

(V.j'enchev, B.ConntantlnoT, K. Ivrjiora) . $2

Determination of Photon 'Xi1.put Factora for To b'aohinae (K.Tobola,P.Hnnliril»k, J.Novutny, I.K.ovnr, R.Waêr, I.Jirounek) 53

Doalme.ry In Teletherapy In Oraoow (W.osyanzyk, J.Leelak, I.Tolok, B.Po—

lak) , 60Comparison of Theoretical and Experimental Iwaa riotrltiutiono Generated

by Therapeutic Electron Beans (I.Hlara'c'ova', K.Tobola, D.SpaikoT*). . . . . . . . 67Build up Turrea and Awall Correction, Paotor lo Co Baaaa tl.Korir,

J.Kovotny) • • • . . . 7?Pitfall* in In-rlve toalaetry with Tharneluninlncence Losaaatara (M.Gant-

rjIfW) 77

i>ealn»try of Mew 'oaeaiua Uouroea before their Applloatlao to Cllaloal

Praotloe (H.ZaJkara, V.Kubao, H.StankuaoTa, K.Stopak, T.Slano) 82

Heary Charged i. rtlole Ooalaetry, Theory and Applloatlen (J.V.Haoaan}....... 86

Paaalvo ljetaotera for Paat lautrea Therapy Beaaa (F.Spumy)................. 9^

Slaw neutron flux Dlatrlbutlam ifi Phaatea Irradiated by C*lllaat«4 Baaaa

of ? 5 2CP leutrene (P.A.Bl-Bakkoueh, T.S.Akki, R.M.Me.Tahld) 9«

- 19? -

St:

I I I . Equipment and Quality Agguranoo In Radiotherapy. III t PrietroJo-v& teconlka a zafcezpagenie kvallty T rid lot ere.pl 1. , 105

Cart - a ScandinaTlan Approaoh to Computer Aided Radiation Therapy(R.Walatam)... ,, 105

Conservs*.lTe Treatment of Breaat Carolnoaa wltii I n t ar a t l t i a l Booat Do-se (E.LOffler) „. 109

Computer-aided Decision-making for =*rly Detection of Breast Cancer*

Using Puzzy Clanslflcntlon (W.Sohfller) 116

Clinical bxperlenoe froa 10-50 UeV Hedioal Wlcrotron* {R.Walataa) 119Kobaltov4 ozalove£e - T^ere, dnee a t i t r a (L.Fi-nel , V.Eubeo, J.Zaaec'-

nik) 125Zpaaob riimni uryohlorac'e pfl pohybore terapll {J.Ochee, P. Bednar)......... 127

Quality Assurance in Radiation Therapyt Phyaloal Aapeota (J.iorotni, Z.Ko-

var) 132

Quality Assuranoe la Radiation Therapy: Ionlzatlon Chaaber Calibration

and Interooaparlson of Absorbed Doaea (V.LaglnoTi, B.Pleake, J.RoTotn^,

I.Korrff, P.JlrouSek, R.Wagner) 140

Bestrahlungsraua fOr Qama-Deutronen Braohyteraple mlt den Ruklid Callfor-

nium-252 In VTJKEO Brno (V.Kryfitof, T.TaSer, O.Ott) 144

Pi'Oton Therapy Coaplaz with Three Procedure Rooaa (I.V.Churllo, L.L.Gol-

4In, V.S.KhornshkoT, S.I.Blolchln, V.U.BrejaT, I.A.VcrontiiOT, J.L.^lein-

book, S.F.LlaeTete, U.P.LemanoT, L.M.Parlonalcy, O.F.PedotoT, S.G.Shia-

ohuolt, V.J.WedTed, V.V.JeraolaJer) , 146

Eapecial Topometrlo and Doalaetrlo ?eaturea of Different Proton Irradia-

tion Technique* (V.S.Khoroshkor, r..V.BelJaikln, V.H.BreJaT, V.I.Eoat-

Juchenko, S.P.Llaoreta, M.P.LomanoT, V.P.PoohTata,. G.C.SMachuck.V.A.

Kryankyi) 153

IV. Radiation Proteotlen Probleaa In Radiotherapy. IT. Problc'ay radlatnej

ocbratur * radlotarapll. 162

Doses to Personnel Engaged in Radiation Treatment of Cancer Patienta in

Kuwait during 1980-85 (Y.Y.Bakin, S.D.Al-Zenki, J.Sabel) 162

Measurement of Number Albede for Baokaoattered 662 keV Photon* froa Stra-

tified Layere of Conoret* and. Lead (A.BhattacharJea, A.K.Sinha) 164

Dependence of Effeotlre Linear Attenuatien Coefficient on X-ray Tub* Vol-

tage Ripple (T.Poruberky) 169

Spectroaetry of I-raya froa 10 to 300 kaV (F.Pernifka) 173

V. Biological Probleaa in Radiotherapy. V. Blologlok< problear radiatera-

Huaan SurrlTal froa Radiatlen Expeeure (J.H.Martln) 178

Cuaulatlre Iffeot In Traotienatien and the Choloe of Radletberapeutloal

Traataent Sotaeae* (I.Pr»kei, M.LekaJiBek, I.Judaa) 188

A Methed for Radiation Treataent ot Malignant Baaepharyngeal Tueisura and

Reaulta of ita Applloatlon ea 228 Patia»t» (T.PmBdera, M.Oantohew,

Z.IauaeTa, V.MilteheT) 190

íí.-.OTl

Hlavní raíaitan

E«4akola>i

Vydali

Tyt1*511i

Padat výtlaSkaTt

Aktuality * kllnlokaj onkológla, 14

KUDr. P»t»r ;»i>5»k, CSe.

KUCr. PJ.tr. Josef Halk*PhLr. Júllua Strlaks, CSe.

tfatar kllnlok*} onkelégl* v BrktlalaT*.HaydokoT* 10 ae ailhlaaaa HlnlatsratTia sdra-retBÍotra SSRi . Z-8191/19aO-B/12 s« d&a 9. 2 . 1981

Tllaapraaa IK»V Tabruoká ul . i . 6, Bratlalavm

1 200

Urř«B< fra pctratu pnoormiktr gdrvratníokjali Kr la lmí

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