Table 9.
Mean and standard deviation, in parentheses, of calculated CTDIw values for a 16 and 32 cm CTDI phantom; “-” indicates that the scanner does not offer that bowtie option. CTDIw values were normalized to 100 mA s to account for differences in scanning protocols used on the different scanner models.
| CTDIw for a 16 cm phantom (mGy∕100 mA s) | ||||
|---|---|---|---|---|
| kVp | Bowtie | GE VCT | GE LightSpeed 16 | Siemens Sensation 64 |
| 80 | Small | 6.6 (0.1) | 6.4 (0.1) | - |
| 80 | Medium | 7.6 (0.2) | - | - |
| 80 | Large | - | - | 3.9 (0.1) |
| 100 | Small | 11.9 (0.2) | 11.6 (0.2) | - |
| 100 | Medium | 13.5 (0.3) | - | - |
| 100 | Large | - | - | 8.0 (0.2) |
| 120 | Small | 18.1 (0.3) | 17.7 (0.3) | - |
| 120 | Medium | 20.4 (0.4) | - | - |
| 120 | Large | - | - | 13.4 (0.3) |
| 140 | Small | 25.1 (0.3) | 24.7 (0.4) | - |
| 140 | Medium | 28.2 (0.4) | - | - |
| 140 | Large | - | - | 20.3 (0.5) |
| CTDIw for a 32 cm CTDI phantom (mGy∕100 mA s) | ||||
| 80 | Large | 2.9 (0.1) | 2.8 (0.0) | 1.7 (0.0) |
| 100 | Large | 5.6 (0.1) | 5.5 (0.1) | 3.7 (0.1) |
| 120 | Large | 8.9 (0.1) | 8.7 (0.2) | 6.5 (0.1) |
| 140 | Large | 12.7 (0.2) | 12.6 (0.2) | 10.1 (0.2) |