Ionizing strongRadiationstrong in Abdominal CT Unindicated Multiphase.pdfVIP

Ionizing Radiation in Abdominal CT: Unindicated Multiphase Scans Are an Important Source of Medically Unnecessary Exposure a a a,b Kristie M. Guite, MD , J. Louis Hinshaw, MD , Frank N. Ranallo, PhD , c a Mary J. Lindstrom, PhD , Fred T. Lee Jr, MD Purpose: CT radiation exposure has come under increasing scrutiny because of dramatically increased utilization. Multiphase CT studies (repeated scanning before and after contrast injection) are a potentially important, overlooked source of medically unnecessary radiation because of the dose-multiplier effect of extra phases. The purpose of this study was to determine the frequency of unindicated multiphase scanning and resultant excess radiation exposure in a sample referral population. Methods: Abdominal and pelvic CT examinations (n 500) performed at outside institutions submitted for tertiary interpretation were retrospectively reviewed for (1) the appropriateness of each phase on the basis of clinical indication and ACR Appropriateness Criteria® and (2) per phase and total radiation effective dose. Results: A total of 978 phases were performed in 500 patients; 52.8% (264 of 500) received phases that were not supported by ACR criteria. Overall, 35.8% of phases (350 of 978) were unindicated, most commonly being delayed imaging (272 of 350). The mean overall total radiation effective dose per patient was 25.8 mSv (95% confidence interval, 24.2-27.5 mSv). The mean effective dose for unindicated phases was 13.1 mSv (95% confidence interval, 12.3-14.0 mSv), resulting in a mean exce