Table 2.
Radiation dose metrics and technical parameters overall and stratified by patient size category
| Variable (units) | Patient size category | |||||||
|---|---|---|---|---|---|---|---|---|
| All patients | Small | Medium | Large | |||||
| n = 748,846 | n = 165,816 | n = 360,850 | n = 222,180 | |||||
| Mean | Std Dev | Mean | Std Dev | Mean | Std Dev | Mean | Std Dev | |
| Patient diameter (mm) | 309 | (45) | 252 | (17) | 301 | (16) | 363 | (28) |
| CTDIvol (mGy) | 13 | (7.2) | 8 | (3.3) | 12 | (4.9) | 20 | (7.8) |
| DLP (mGy-cm) | 798 | (546) | 447 | (283) | 701 | (404) | 1217 | (629) |
| Effective dose (mSv) | 13 | (8) | 9 | (6) | 12 | (7) | 16 | (9) |
| mAs | 181 | (89) | 120 | (55) | 166 | (68) | 251 | (94) |
| Pitch* | 1.0 | (0.3) | 1.0 | (0.2) | 1.0 | (0.3) | 1.0 | (0.3) |
| Effective mAs | 183 | (95) | 118 | (54) | 166 | (67) | 260 | (106) |
| kV (kilovoltage) | 119 | (7.5) | 116 | (8.0) | 118 | (7.4) | 121 | (6.8) |
| Scan length (cm) | 48 | (9.2) | 45 | (8.8) | 48 | (9.0) | 51 | (9.2) |
| Slice thickness (mm) | 3.7 | (1.6) | 3.7 | (1.7) | 3.7 | (1.6) | 3.7 | (1.6) |
| Number of phases | 1.3 | (0.7) | 1.3 | (0.7) | 1.3 | (0.7) | 1.3 | (0.6) |
| Calculated size-adjusted variables | ||||||||
| Size-adjusted CTDIvol (mGy) | 12 | (4.6) | 11 | (5.0) | 12 | (4.6) | 12 | (4.2) |
| Size-adjusted DLP (mGy-cm) | 702 | (389) | 690 | (448) | 701 | (388) | 712 | (338) |
Abbreviations: CTDIvol volumetric computed tomography dose index, DLP dose length product, mAs milliampere-seconds, mGy milliGray, mSv millisieverts
*Table distance traveled in one 360° gantry rotation divided by beam collimation