Table 6.
Mean and standard deviation, in parentheses, of CTDI100,air calculated values; “-” indicates the scanner either does not offer that bowtie option or that beam width. CTDI100,air values were normalized to 100 mA s to account for differences in scanning protocols used on the different scanner makes and models.
| kVp | Beam width (mm)a | Bowtie | CTDI100,air (mGy∕100 mA s) | ||
|---|---|---|---|---|---|
| GE VCT | GE LightSpeed 16 | Siemens Sensation 64 | |||
| 80 | 20, 40 | Small | 12.4 (0.3) | 11.4 (0.1) | - |
| 80 | 40 | Medium | 12.4 (0.3) | - | - |
| 80 | 20, 28.8, 40 | Large | 8.9 (0.2) | 8.4 (0.1) | 5.8 (0.1) |
| 100 | 20, 40 | Small | 20.4 (0.4) | 19.1 (0.2) | - |
| 100 | 40 | Medium | 20.3 (0.4) | - | - |
| 100 | 20, 28.8, 40 | Large | 15.6 (0.2) | 15.0 (0.2) | 11.1 (0.3) |
| 120 | 5 | Small | 46.7 (1.4) | 43.5 (0.9) | - |
| 120 | 10 | Small | 37.3 (0.7) | 35.0 (0.5) | - |
| 120 | 20 | Small | 31.4 (0.4) | 28.0 (0.4) | - |
| 120 | 40 | Small | 29.5 (0.5) | - | - |
| 120 | 5 | Medium | 46.7 (1.5) | - | - |
| 120 | 10 | Medium | 37.3 (0.8) | - | - |
| 120 | 20 | Medium | 31.4 (0.5) | - | - |
| 120 | 40 | Medium | 29.4 (0.5) | - | - |
| 120 | 5 | Large | 37.7 (1.2) | 35.9 (0.7) | 16.2 (0.3) |
| 120 | 10 | Large | 30.1 (0.5) | 28.8 (0.4) | 16.3 (0.3) |
| 120 | 19.2 | Large | - | - | 19.6 (0.3) |
| 120 | 20 | Large | 25.3 (0.3) | 23.1 (0.3) | - |
| 120 | 28.8 | Large | - | - | 18.1 (0.3) |
| 120 | 40 | Large | 23.8 (0.3) | - | - |
| 140 | 20, 40 | Small | 39.7 (0.6) | 38.1 (0.5) | - |
| 140 | 40 | Medium | 39.6 (0.6) | - | - |
| 140 | 20, 28.8, 40 | Large | 33.1 (0.4) | 32.4 (0.5) | 27.2 (0.5) |
a
At 80, 100, and 140 kVp, nominal beam widths of 20, 28.8, and 40 mm were tested exclusively on the GE LightSpeed 16, Siemens Sensation 64, and GE VCT scanners, respectively.