| Table 1 | Analysis of estimated values of CTDIw from surveys of CT practice, expressed in terms of absorbed dose to air |
| Examination type | CTDIw (mGy) | |||||||
| Sample size | Mean | SD | Min | 25% | Median | 75% | Max | |
| Heada | 102 | 50.0 | 14.6 | 21.0 | 41.9 | 49.6 | 57.8 | 130 |
| Face and sinusesb | 20 | 31.7 | 15.9 | - | 19.9 | 28.0 | 35.2 | - |
| Vertebral traumab | 20 | 44.1 | 21.5 | - | 29.4 | 39.7 | 68.3 | - |
| Chesta | 88 | 20.3 | 7.6 | 4.0 | 15.2 | 18.6 | 26.8 | 46.4 |
| HRCT of lungb | 20 | 31.7 | 14.9 | - | 19.4 | 31.0 | 35.0 | - |
| Abdomena | 91 | 25.6 | 8.4 | 6.8 | 18.8 | 24.8 | 32.8 | 46.4 |
| Liver and spleenb | 15 | 26.1 | 11.3 | - | 15.4 | 25.0 | 34.0 | - |
| Pelvisa | 82 | 26.4 | 9.6 | 6.8 | 18.5 | 26.0 | 33.1 | 55.2 |
| Osseous pelvisb | 16 | 24.7 | 17.8 | - | 14.8 | 20.0 | 24.6 | - |
| a. | Estimated values from UK survey data(8) |
| b. | Dose data from Pilot Study (33) |
| Table 2 | Analysis of estimated values of DLP from surveys of CT practice on the basis of absorbed dose to air (mGy cm) |
| Examination type | DLP (mGy cm) | |||||||
| Sample size | Mean | SD | Min | 25% | Median | 75% | Max | |
| Heada | 102 | 882 | 332 | 231 | 673 | 795 | 1045 | 2087 |
| Face and sinusesb | 20 | 259 | 118 | 158 | 180 | 204 | 353 | 506 |
| Vertebral traumab | 20 | 392 | 214 | 40 | 254 | 353 | 455 | 914 |
| Chesta | 88 | 517 | 243 | 72 | 349 | 490 | 649 | 1304 |
| HRCT of lungb | 20 | 200 | 71 | 100 | 136 | 199 | 278 | 312 |
| Abdomena | 91 | 597 | 281 | 115 | 415 | 525 | 774 | 1874 |
| Liver and spleenb | 20 | 658 | 293 | 151 | 485 | 651 | 894 | 1181 |
| Pelvisa | 82 | 443 | 233 | 68 | 266 | 416 | 566 | 1324 |
| Osseous pelvisb | 16 | 514 | 426 | 43 | 225 | 465 | 518 | 1758 |
| a. | Estimated values from UK survey data(8) |
| b. | Dose data from Pilot Study (33) |
| Table 3 | Proposed reference dose values for routine CT examinations on the basis of absorbed dose to air |
| Examination | Reference dose value | |
| CTDIw (mGy) | DLP (mGy cm) | |
| Routine heada | 60 | 1050 |
| Face and sinusesa | 35 | 360 |
| Vertebral traumab | 70 | 460 |
| Routine chestb | 30 | 650 |
| HRCT of lungb | 35 | 280 |
| Routine abdomenb | 35 | 780 |
| Liver and spleenb | 35 | 900 |
| Routine pelvisb | 35 | 570 |
| Osseous pelvisb | 25 | 520 |
| a. | Data relate to head phantom (PMMA, 16 cm diameter) |
| b. | Data relate to body phantom (PMMA, 32 cm diameter) |
| Figure 1 | Histogram of CTDIw data for routine head examinations in the UK, on the basis of absorbed dose to air |
| Figure 2 | Histogram of DLP data for routine head examinations in the UK, on the basis of absorbed dose to air |
| Figure 3 | Histogram of CTDIair data for routine head examinations in the UK, expressed in terms of absorbed dose to air |
