Radiation exposure in concurrent abdominoplevic and chest CT Scans: an analysis of overlap and clinical impact

This study investigated the additional radiation exposure, influencing factors, and clinical significance of overlapping Z-axis coverage in abdominopelvic CT scans performed consecutively after same-day chest CT scans. Data from 761 patients were analyzed, with measuring the total and overlapping Z-axis coverage of the portal venous phase in abdominopelvic CT scans. The average overlapping portion was 33.8 ± 12.1 mm, accounting for approximately 7.0% of the total scan length, contributing a dose-length product of 33.4 mGy*cm and an effective radiation dose of 0.5 mSv. Male sex and the total scan length were identified as significant factors influencing overlap (p = 0.002 and < 0.001, respectively). Despite overlapping scans frequently imaging the lower lungs, only 8.4% of abdominopelvic CT reports specifically mentioned lower lung abnormalities, indicating limited clinical utility. These findings underscore the importance of optimizing CT protocols to minimize the total length of the body covered in abdominopelvic scans, thereby reducing unnecessary radiation exposure during concurrent chest and abdominopelvic CT scans.