Post on 29-Jan-2023
Technology Assessment Institute: Summit on CT Dose
Teaching Cases II:
CT Angiography Across the Ages:
Single to 320 Slices
P. Rogalla, M.D.
Dept. of Medical Imaging
University of Toronto
Technology Assessment Institute: Summit on CT Dose
technical issues influencing scanning protocols
and radiation dose
difference b/w scanner generations
slice thickness, pitch, scanning times
consequences for contrast media injection
clinical examples
technical issues influencing scanning protocols
and radiation dose
CTA: outline
difference b/w scanner generations
slice thickness, pitch, scanning times
consequences for contrast media injection
clinical examples
Technology Assessment Institute: Summit on CT Dose
technical issues influencing scanning protocols
and radiation dose
difference b/w scanner generations
slice thickness, pitch, scanning times
consequences for contrast media injection
clinical examples
CTA: outline
Technology Assessment Institute: Summit on CT Dose
X-ray shutterX-ray shutter“over-ranging”
scanning area
additional rotation additional rotation
Technology Assessment Institute: Summit on CT Dose
scanning area
additional rotation additional rotation
X-ray shutterX-ray shutter“over-ranging”
Technology Assessment Institute: Summit on CT Dose
scanning area
additional rotation additional rotation
X-ray shutterX-ray shutter“over-ranging”
Technology Assessment Institute: Summit on CT Dose
wide area detector
16 cm16 cm
64-slice helical
additional rotation
Technology Assessment Institute: Summit on CT Dose
512, 48 cm
51
2, 4
8 c
mpixel size:
0.94 mm
. . . . . . . . . . .
0.94
slice thickness:
1 mm
Technology Assessment Institute: Summit on CT Dose
512, 48 cm
51
2, 4
8 c
m
0.94 mm
1 mm
. . . . . . . . . . .
0.94
1.0
slice thickness:
pixel size:
Technology Assessment Institute: Summit on CT Dose
technical issues influencing scanning protocols
and radiation dose
difference b/w scanner generations
slice thickness, pitch, scanning times
consequences for contrast media injection
clinical examples
CTA: outline
Technology Assessment Institute: Summit on CT Dose
technical issues influencing scanning protocols
and radiation dose
difference b/w scanner generations
slice thickness, pitch, scanning times
consequences for contrast media injection
clinical examples
CTA: outline
Technology Assessment Institute: Summit on CT Dose
technical issues influencing scanning protocols
and radiation dose
difference b/w scanner generations
slice thickness, pitch, scanning times
consequences for contrast media injection
clinical examples
CTA: outline
Technology Assessment Institute: Summit on CT Dose
technical issues influencing scanning protocols
and radiation dose
difference b/w scanner generations
slice thickness, pitch, scanning times
consequences for contrast media injection
clinical examples
CTA: outline
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
13 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
8 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
5 s
40 cm
Scan time
0.5 s 16-slice CT
Collimation Pitch factor
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm125 s
Slice thickness, pitch
0.3 s 64-slice CT0.5 s 16-slice CT0.5 s 4 -slice CT
40 cm
Scan time
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT0.5 s 16-slice CT0.5 s 4 -slice CT
31 s
40 cm
Scan time
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
5 s
40 cm
Scan time
0.5 s 4 -slice CT0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT0.5 s 16-slice CT0.5 s 4 -slice CT
100 s
40 cm
Scan time
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
25 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
4 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
83 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
21 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
3 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
71 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
18 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
3 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
63 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
16 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
2 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
56 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
14 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
2 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
50 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
13 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
2 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
63 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
16 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
5 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
50 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
13 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
4 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
42 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
10 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
3 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
36 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
9 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
3 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
31 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
8 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
2 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
28 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
7 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
2 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
25 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
6 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
2 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
31 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
8 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
5 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
25 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
6 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
4 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
21 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
5 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
3 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
18 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
4 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
3 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
16 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
4 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
2 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
14 s
40 cm
Scan time
0.5 s 16-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
3 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.5 mm
1.0 mm
2.0 mm
5.0 mm
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
2 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
13 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
3 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
2 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
13 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
8 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
5 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
10 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
6 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
4 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
8 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
5 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
3 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
7 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
4 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
3 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
6 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
4 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
2 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
6 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
3 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
2 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch
0.3 s 64-slice CT
0.5 s 4 -slice CT
5 s
40 cm
Scan time
0.5 s 16-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor
Slice thickness, pitch0.5 s 16-slice CT
3 s
40 cm
Scan time
0.5 s 4 -slice CT
0.3 s 64-slice CT
0.5 mm
1.0 mm
2.0 mm
5.0 mm
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.8
1.0
1.2
1.4
1.6
1.8
2.0
3.0 mm
4.0 mm
8.0 mm
Collimation Pitch factor0.3 s 64-slice CT
0.5 s 4 -slice CTSlice thickness, pitch
2 s
40 cm
Scan time
0.5 s 16-slice CT
Injection speed, enhancement
http://www.ctisus.org/cta_web/12_04/12_04_Heiken/jpgs/Heiken_figure02.jpg
Source: Joachim Wildberger. Fleischmann D, Radiology 2005
0
50
100
150
200
250
300
0 20 40 60 80 100 120
time [s]
Rela
tive
En
ha
nc
em
en
t [
HU
]
2 ml / s
150 HU
Time frame: 32 s
32 s
20 40 60 80 100 120
time [s]
0
50
100
150
200
250
300
0R
ela
tive
En
ha
nc
em
en
t [H
U]
220 HU
16 s
Time frame: 16 s
4 ml / s
Injection speed, enhancement
Injection duration
Source: Joachim Wildberger 30s Injection
20s Injection
12s Injecton
8s Injection
5s Injection
3s Injection
1s Injection
0
50
100
150
200
250
300
350
0 5 10 15 20 25 30 35
Ao
rtic
En
ha
nce
me
nt (H
U)
time (after start of injection) (s)
0
50
100
150
200
250
300
350
0 5 10 15 20 25 30 35 40
Ao
rtic
En
ha
nce
me
nt (H
U)
time (after start of Injection) (s)
Saline chaser
Source: Joachim Wildberger
400
300
200
100
0 4020 8060
112 ml CM
112 ml CM
&
50 ml saline
4 cc / s
Technology Assessment Institute: Summit on CT Dose
technical issues influencing scanning protocols
and radiation dose
difference b/w scanner generations
slice thickness, pitch, scanning times
consequences for contrast media injection
clinical examples
CTA: outline
Technology Assessment Institute: Summit on CT Dose
technical issues influencing scanning protocols
and radiation dose
difference b/w scanner generations
slice thickness, pitch, scanning times
consequences for contrast media injection
clinical examples
CTA: outline
Technology Assessment Institute: Summit on CT Dose
scanner: 4, 16, 64, 320?
tube settings, amount of contrast material?
newborn, partially corrected Fallot
suspected arterial and venous abnormalities
< 2 kg BW
scanner: 4, 16, 64, 320?
tube settings, amount of contrast material?
Technology Assessment Institute: Summit on CT Dose
0
10
20
30
40
50
60
70
80
90
0 10 20 30 40 50 60
body weight [kg]
[mA
s]
0
10
20
30
40
50
60
0 10 20 30 40 50
body weight [kg]
[mA
s]
0
50
100
150
200
250
0 10 20 30 40 50
body weight [kg]
[mA
s]
Chest
Abdomen
Head
observed mAs settings
in paediatric CT
Technology Assessment Institute: Summit on CT Dose
Exposure ~ Voltage 2.5
150 %
140 kV
100 %
120 kV
40 %
80 kV
Rel. Dose
Voltage
mAs x 2.5 at 80 kV
mA adaptation at 120 kV:
(body weight [kg] + 5) x f = mAs
f = 1 (chest), 1.5 (abdomen), 5 (head)
Exposure ~ Voltage 2.5
150 %
140 kV
100 %
120 kV
40 %
80 kV
Rel. Dose
Voltage
mAs x 2.5 at 80 kV
58 y/o man
ICU:
CTA, search for emboli
64-slice, 0.5 s rotation,
0.5 mm slices,
10 s acquisition time
58 y/o man
ICU:
CTA, search for emboli
64-slice, 0.5 s rotation,
0.5 mm slices,
10 s acquisition time
58 y/o man
ICU:
CTA, search for emboli
64-slice, 0.5 s rotation,
0.5 mm slices,
10 s acquisition time
58 y/o man
ICU:
CTA, search for emboli
64-slice, 0.5 s rotation,
0.5 mm slices,
10 s acquisition time
Diagnoses:
pneumonia,
vascular calcifications,
left renal artery
occlusion
58 y/o man
ICU:
CTA, search for emboli
64-slice, 0.5 s rotation,
0.5 mm slices,
10 s acquisition time
Technology Assessment Institute: Summit on CT Dose
isotropic scanning technique for CTA
caveat: thin slices with 4-slice CT scanners
arterial phase: bolus tracking
scanning time dependent on slice thickness,
pitch, scanner type – influences amount and
injection speed of CM
isotropic scanning technique for CTA
Summary
caveat: thin slices with 4-slice CT scanners
arterial phase: bolus tracking
scanning time dependent on slice thickness,
pitch, scanner type – influences amount and
injection speed of CM