Organ doses and effective dose in chest CT with and without the influence of overranging: A patient study using VirtualDoseCT

This study investigates the influence of overranging (OR) on the effective dose (ED) and organ doses (ODs) in adult patients undergoing chest computed tomography (CT) examinations. A total of 111 adult patients (65 males, 46 females) who underwent chest CT at the University Hospital of Patras between July 2022 and February 2023 were included. Demographic and anatomical data, along with exposure parameters were retrieved from the hospital's PACS. All scans were performed using a Toshiba Aquilion Prime 80-slice multidetector CT scanner. Radiation dose values were calculated with and without the influence of the OR using the VirtualDoseCT software. OR resulted in significant increases in ED across all groups (Wilcoxon signed-rank test, p < 0.0001). The median ED for the total sample increased from 6.96 to 7.69 mSv (+10.5%), with a higher relative increase (6.49 to 7.35 mSv) (+13.3%) in females compared to males (7.25 to 8.04 mSv) (+10.9%). Median ODs increased significantly due to OR (p < 0.0001), particularly for organs located at the boundaries of the scanning field (colon, thyroid, stomach, liver, kidneys, spleen), where percentage increases reached up to 67% (for colon). In contrast, organs within the field (lungs, heart, breast, and oesophagus) showed smaller relative increases (up to 7.4% for oesophagus), while organs outside the field (gonads, bladder, eye lenses uterus/cervix, and prostate) received lower absolute doses but exhibited notable percentage increases in some cases (up to 49% for uterus). Significant sex-based differences in ODs were found for all organs (Mann–Whitney test, p < 0.05), except for the thyroid and eye lenses. In summary, OR during chest CT leads to a greater increase in ED for female patients and for ODs for organs positioned at the boundaries of the scan region. These findings underscore the importance of optimizing scan length to minimize unnecessary radiation, in line with the ALARA principle. • Overranging increases chest CT effective dose, more in females. • Boundary organs exhibit highest dose increases due to overranging. • Significant sex-based differences in organ doses were observed. • Findings support scan length control and ALARA-based practices.