With the recent completion of AAPM Report 293, a trilogy of reports by the American Association of Physicists in Medicine (AAPM) on the calculation of CT Size-Specific Dose Estimates (SSDE) now includes head CT. SSDE provides a more accurate estimate of patient dose to better inform end-users when they are developing and reviewing size-based CT protocols, especially for pediatrics. Initially, SSDE was developed to more accurately estimate radiation dose for chest and abdominopelvic CT. To calculate SSDE, a conversion factor (CF), ranging between 2.75-to-0.75 (newborns-to-adults),...
Description of activity and work performed
In 2019, the use of Dw was expanded to include conversion factors for head CT (Report 293). For this presentation, 620 Head SSDE CFs (i.e., fH16) were calculated based on anteroposterior (AP), lateral (LAT), effective diameter (eff. Dia.), and Dw calculations, [Fig. 1]. The resulting average patient ranges, [Fig. 2] are reported based on patient’s age and weight, and demonstrated fH16 CFs, [Fig. 3] that ranged from 1.2-to-0.8 (newborns-to-adults), [Table 1]. A comparison of head and body CFs, based on the 16-cm diameter CTDI phantom,...
Conclusion and recommendations
The CT dose index (i.e., CTDIvol) reported during a patient head examination does not represent absorbed dose to the patient. To better estimate actual patient dose, a conversion factor based on the patient's head size and attenuation properties can be calculated using the guidance set forth in the AAPM's Report 293. The conversion factors reported in this study [1.2-to-0.8 (newborns-to-adults)], as derived using AAPM's Report 293, will scale the patient's examination CTDIvol to better approximate absorbed dose to the center othe patient's head. SSDE for...
D. P. Frush; Durham, NC/US - nothing to disclose K. J. Strauss; Cincinnati, OH, OH/US - nothing to disclose S. L. Brady; Cincinnati, OH/US - nothing to disclose S. McKenney; Stanford, CA/US - nothing to disclose
1.AAPM Rpt 293. Size Specific dose Estimate (SSDE) for Head CT. The Report of AAPM Task Group 293 (2019); URL: https://www.aapm.org/pubs/reports/detail.asp?docid=185
2.Strauss et al. Improved Estimates of Trunk and Head CT Radiation Dose: Development of Size-Specific Dose Estimate JACR 2020 (In Press); DOI: https://doi.org/10.1016/j.jacr.2019.11.006