Cardiac-Specific Conversion Factors to Estimate Radiation Effective Dose From Dose-Length Product in Computed Tomography
Table 4
Conversion Factors Relating Effective Dose to Dose-Length Product, Using Current Definition of Effective Dose
ICRP 103 | Prospective Axial | Prospective Axial Padding | Prospective Helical | ICRP 103 | Retrospective Helical | Retrospective Helical TCM∗ | Calcium | Average | CV [%] | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Scanner/kVp | 80 | 100 | 120 | 80 | 100 | 120 | 80 | 100 | 120 | Scanner/kVp | 80 | 100 | 120 | 80 | 100 | 120 | 120 | ||
GE Lightspeed VCT XTe | 0.0259 | 0.0298 | 0.0295 | 0.0263 | 0.0283 | 0.0290 | x | x | x | GE Lightspeed VCT XTe | 0.0242 | 0.0267 | 0.0264 | 0.0243 | 0.0259 | 0.0269 | 0.0306† | 0.0275 | 8.0 |
GE Discovery CT750 HD | x | 0.0302 | x | 0.0262‡ | 0.0278‡ | 0.0283‡ | x | x | x | GE Discovery CT750 HD | x | 0.0284 | 0.0267 | x | 0.0268 | 0.0269 | 0.0285 | 0.0277 | 4.4 |
Hitachi Scenaria | 0.0254 | 0.0272 | 0.0277 | 0.0260 | 0.0268 | 0.0281 | x | x | x | Hitachi Scenaria | 0.0258 | 0.0272 | 0.0281 | x | x | x | 0.0265 | 0.0269 | 3.5 |
Philips Brilliance 64 | x | x | x | x | x | x | x | x | x | Philips Brilliance 64 | 0.0249 | 0.0260 | 0.0261 | 0.0246 | 0.0260 | 0.0267 | 0.0285 | 0.0261 | 4.9 |
Philips Brilliance iCT 256 | 0.0301 | 0.0314 | 0.0316 | 0.0279 | 0.0295 | 0.0303 | x | x | x | Philips Brilliance iCT 256 | 0.0242§ | 0.0254§ | 0.0254§ | 0.0231 | 0.0248 | 0.0249 | x | 0.0274 | 11.2 |
Siemens SOMATOM Sensation 64 | 0.0264 | 0.0268 | 0.0266 | x | x | x | x | x | x | Siemens SOMATOM Sensation 64 | 0.0250 | 0.0249 | 0.0249 | 0.0256 | 0.0253 | 0.0251 | x | 0.0256 | 3.0 |
Siemens SOMATOM Definition AS+ | 0.0271 | 0.0275 | 0.0273 | 0.0256 | x | 0.0257 | x | x | x | Siemens SOMATOM Definition AS+ | 0.0243 | 0.0251 | 0.0246 | 0.0244 | 0.0252 | 0.0250 | x | 0.0256 | 4.6 |
Siemens SOMATOM Definition | 0.0288 | 0.0288 | 0.0274 | x | x | x | x | x | x | Siemens SOMATOM Definition | 0.0259 | 0.0286 | 0.0262 | 0.0271 | 0.0287 | 0.0281 | x | 0.0277 | 4.1 |
Siemens SOMATOM Definition FLASH | 0.0253 | 0.0266 | 0.0254 | 0.0240 | 0.0252 | 0.0256 | 0.0263 | 0.0268 | 0.0266 | Siemens SOMATOM Definition FLASH | 0.0203 | 0.0256 | 0.0256 | 0.0230 | 0.0243 | 0.0248 | x | 0.0250 | 6.7 |
Toshiba Aquilion 64 | x | x | x | x | x | x | x | x | x | Toshiba Aquilion 64 | x | 0.0241 | 0.0252 | x | 0.0231 | 0.0236 | 0.0349 | 0.0262 | 18.8 |
Toshiba Aquilion Prime | x | x | x | x | x | x | 0.0209 | 0.0229 | 0.0242 | Toshiba Aquilion Prime | 0.0208 | 0.0231 | 0.0232 | 0.0212 | 0.0233 | 0.0234 | 0.0256 | 0.0229 | 6.7 |
Toshiba Aquilion ONE | x | 0.0227‖ | 0.0250‖ | 0.0229¶ | 0.0259¶ | 0.0261¶ | x | x | x | Toshiba Aquilion ONE | x | x | x | x | x | x | 0.0257 | 0.0247 | 6.2 |
Average, per protocol type & kV | 0.0270 | 0.0279 | 0.0276 | 0.0256 | 0.0273 | 0.0277 | 0.0236 | 0.0248 | 0.0254 | Average, per protocol type & kV | 0.0239 | 0.0259 | 0.0257 | 0.0242 | 0.0253 | 0.0256 | 0.0289 | ||
CV, % | 6.8 | 9.2 | 7.8 | 6.1 | 5.4 | 6.2 | 16.0 | 10.9 | 6.6 | CV, % | 8.6 | 6.6 | 4.9 | 7.3 | 6.6 | 6.0 | 10.9 | ||
Average, per protocol type, all kV | 0.0275 | 0.0269 | 0.0246 | Average, per protocol type, all kV | 0.0253 | 0.0251 | |||||||||||||
CV, % | 7.9 | 6.6 | 9.6 | CV, % | 7.3 | 6.8 | |||||||||||||
Average, all prospective axial (with and without padding) | 0.0272 | Average, all retrospective helical (with and without TCM) | 0.0252 | ||||||||||||||||
CV, % | 7.3 | CV, % | 7.0 | ||||||||||||||||
Average, all protocols (prospective, retrospective, and calcium scoring) | 0.0262 | Average, all protocols (prospective, retrospective, and calcium scoring) | 0.0262 | ||||||||||||||||
CV, % | 8.9 | CV, % | 8.9 |
Scanner- and protocol-specific k-factors, in units of mSv·mGy−1cm−1, were calculated for cardiac CT using ICRP Publication 103 definition of effective dose, for 12 scanners and 120 scan protocols with standard tube potentials of 80, 100, and 120 kVp. k-Factors here are summarized in 5 categories of axial and helical CT angiography protocol types, and calcium score. Per-scanner averages of the k-factors across all protocol types and energy levels are displayed along with the CV in the 2 right-most columns. Scan length for all scans is 13.3 to 14.2 cm. Heart rate is 60 beats/min for all scans, except where otherwise noted. A detailed description of each protocol here is also provided in Online Table 1, as are additional k-factors and detailed descriptions for very low (70 kVp) and high (135 or 140 kVp) tube potential protocols for selected scanners.
CV = coefficient of variation (ratio of standard deviation to mean in percentage values); other abbreviations as in Tables 1, 2, and 3 .