Radiation doses in consecutive ct examinations from five university of California medical centers¹

Purpose: To summarize data on computed tomographic (CT) radiation doses collected from consecutive CT examinations performed at 12 facilities that can contribute to the creation of reference levels. Materials and Methods: The study was approved by the institutional review boards of the collaborating institutions and was compliant with HIPAA. Radiation dose metrics were prospectively and electronically collected from 199 656 consecutive CT examinations in 83 181 adults and 3871 consecutive CT examinations in 2609 children at the five University of California medical centers during 2013. The median volume CT dose index (CTDIvol), dose-length product (DLP), and effective dose, along with the interquartile range (IQR), were calculated separately for adults and children and stratified according to anatomic region. Distributions for DLP and effective dose are reported for single-phase examinations, multiphase examinations, and all examinations. Results: For adults, the median CTDIvol was 50 mGy (IQR, 37-62 mGy) for the head, 12 mGy (IQR, 7-17 mGy) for the chest, and 12 mGy (IQR, 8-17 mGy) for the abdomen. The median DLPs for single-phase, multiphase, and all examinations, respectively, were as follows: head, 880 mGy cm (IQR, 640-1120 mGy cm), 1550 mGy cm (IQR, 1150-2130 mGy cm), and 960 mGy cm (IQR, 690-1300 mGy cm); chest, 420 mGy cm (IQR, 260-610 mGy cm), 880 mGy cm (IQR, 570-1430 mGy cm), and 550 mGy cm (IQR 320-830 mGy cm); and abdomen, 580 mGy cm (IQR, 360-860 mGy cm), 1220 mGy cm (IQR, 850-1790 mGy cm), and 960 mGy cm (IQR, 600-1460 mGy cm). Median effective doses for single-phase, multiphase, and all examinations, respectively, were as follows: head, 2 mSv (IQR, 1-3 mSv), 4 mSv (IQR, 3-8 mSv), and 2 mSv (IQR, 2-3 mSv); chest, 9 mSv (IQR, 5-13 mSv), 18 mSv (IQR, 12-29 mSv), and 11 mSv (IQR, 6-18 mSv); and abdomen, 10 mSv (IQR, 6-16 mSv), 22 mSv (IQR, 15-32 mSv), and 17 mSv (IQR, 11-26 mSv). In general, values for children were approximately 50% those for adults in the head and 25% those for adults in the chest and abdomen. Conclusion: These summary dose data provide a starting point for institutional evaluation of CT radiation doses.