An assessment of the average glandular dose of breast cone-beam CT in China based on clinical patients

Objectives To quantify the non-compressed breast characteristics of females and the typical scanning parameters of breast cone-beam computed tomography (CBCT), and to provide a preliminary assessment of the average glandular dose (AGD) of breast CBCT in China. Methods This study retrospectively analysed three-dimensional breast imaging data from 1,590 Chinese women who underwent non-enhanced breast CBCT scans in different regions between October 2020 and November 2023. Initially, a semi-automatic measurement tool integrated into the breast CBCT system was used to quantify the breast characteristics for each patient, including effective diameter at the chest-wall (Deff), chest-wall to nipple length (CNL), breast volume (BV), glandular volume (GV), and volumetric breast density (VBD). Then, the AGD for each patient was calculated using the dose conversion factor, combining breast characteristics and scanning parameters. Results The overall median values of Deff, CNL, BV, GV, and VBD reflecting breast characteristics were 12.6 cm, 6.8 cm, 370.6 cm3, 46.7 cm3, and 14.4%, respectively. The tube voltage was fixed at 49 kVp, and the typical tube current was 50 mA. Under the typical scanning parameters, the AGD ranged from 3.9 to 5.1 mGy (median 4.9 mGy). Conclusions The typical AGD for non-enhanced breast CBCT scanning is approximately 1.81 times higher than the cumulative radiation dose from two digital mammography (DM) views in China. Advances in knowledge This study assessed the AGD of patients undergoing breast CBCT examination based on a large amount of clinical data, providing valuable guidance to clinicians in choosing appropriate breast imaging modalities.