Trends and Factors Affecting High-Dose (≥50 mSv) Computed Tomography Scans in the Emergency Department: A Four-Year...

Advances in computed tomography (CT) technology have reduced radiation exposure, with head CTs delivering around 2 mSv. However, some examinations still deliver doses of ≥50 mSv, increasing the risk of radiation-induced cancers.

This study examines the incidence of high-dose CT scans (≥50 mSv) in the emergency department (ED) over a four-year period, exploring trends and potential contributing factors.

This retrospective cohort study examined CT scans from the ED of a tertiary care hospital from 2019 to 2022. Adult patients (≥18 years) who received a single CT scan with a dose ≥50 mSv were included. We analyzed the data by age, sex, scan type, scanner model, use of contrast, and examination year using descriptive statistics and Kruskal-Wallis testing to identify significant variations in radiation dose.

Out of over 166,000 CT scans performed during the study period, we identified 1357 (0.81% of examinations) examinations with radiation doses ≥ 50 mSv, 58% of which were performed on females and 61% <65 years old. Aorta CTs were most common (62%), followed by chest/abdomen/pelvis (14%). Most of these scans were aorta studies (62%), followed by chest/abdomen/pelvis scans (14%) and trauma-related examinations. The highest doses were seen in extremity CTs (median 67 mSv), aorta scans (median 60 mSv), and chest/abdomen/pelvis studies (median 59 mSv). Use of IV contrast was associated with 89% of high-dose scans. The overall percentage of high-dose CTs increased over time, from 0.50% in 2019 to 0.92% in 2022, with a rise in median dose from 57 mSv to 60 mSv. Dose variations were statistically significant across scan type, patient age, contrast use, and year, but not by gender or scanner model.

Although high-dose CT examinations are relatively uncommon, their occurrence in the ED has increased in recent years despite newer CT technology. These scans are most often linked to specific protocols like aortic imaging and multiphase extremity studies. Our findings point to the need for review of CT protocols and better awareness of radiation risks.