The risk of cancer from CT scan radiation is a rising concern in the medical field. Our objective was to determine how many patients received more than 10 CT scans in the ED over the course of 7 years and to quantify their radiation exposure and cancer risk. An electronic chart review was performed at our inner city, academic institution with an annual census of 110,000 patients. All patients who underwent a CT scan performed during ED management between the dates of January 2001 and December 2007 were identified. Specific, pre-determined data elements (eg, subject demographics, type of CT scan) were extracted by 2 researchers blinded to hypothesis, using a pre-formatted data form. After identifying patients with more than 10 CTs performed during the study period, radiation exposure was calculated based on accepted and reported radiation doses for the respective anatomic CTs, and lifetime attributable cancer risk was calculated based on BEIR VII projections (7th report of the Biological Effects of Ionizing Radiation). Over the 7-year study period, 24,393 patients received 34,671 CT scans. 25 (0.1%) patients received more than 10 CTs, 272 (1%) received 5-10 CTs and 4239 (17%) received 2 CTs. Among those with more than 10 CTs, the mean, median, and range for number of CTs were 13.8, 13, and 11-23. The mean age of these patients was 53.3 years, with a range of 26-84 years. Mean radiation exposure was 93.8 mSv (range 24-240). The average lifetime attributable cancer risk above baseline in this group is 0.9% with a range from 0.2% to 2.4%. Among those undergoing CT in our ED, although high exposure patients (>10 scans) constituted a very small minority, attributable cancer risk increases (up to 2.4%) for these patients may have important public health implications.
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