Breast Radiation Exposure of 3D Digital Breast Tomosynthesis Compared to Full-Field Digital Mammography in a Clinical Follow-Up Setting

According to a position paper of the European Commission Initiative on Breast Cancer (ECIBC), DBT is close to being introduced in European breast cancer screening programmes. Our study aimed to examine radiation dose delivered by digital breast tomosynthesis (DBT) and digital mammography (FFDM) in comparison to sole FFDM in a clinical follow-up setting and in an identical patient cohort. Retrospectively, 768 breast examinations of 96 patients were included. Patients received both DBT and FFDM between May 2015 and July 2019: (I) FFDM in cranio-caudal (CC) and DBT in mediolateral oblique (MLO) view, as well as a (II) follow-up examination with FFDM in CC and MLO view. The mean glandular dose (MGD) was determined by the mammography system according to Dance’s model. The MGD (standard deviation (SD), interquartile range (IQR)) was distributed as follows: (I) (CC(FFDM)+MLO(DBT)) (a) left FFDM(CC) 1.40 mGy (0.36 mGy, 1.13–1.59 mGy), left DBT(MLO) 1.62 mGy (0.51 mGy, 1.27–1.82 mGy); (b) right FFDM(CC) 1.36 mGy (0.34 mGy, 1.14–1.51 mGy), right DBT(MLO) 1.59 mGy (0.52 mGy, 1.27–1.62 mGy). (II) (CC(FFDM)+MLO(FFDM)) (a) left FFDM(CC) 1.35 mGy (0.35 mGy, 1.10–1.60 mGy), left FFDM(MLO) 1.40 mGy (0.39 mGy, 1.12–1.59 mGy), (b) right FFDM(CC) 1.35 mGy (0.33 mGy, 1.12–1.48 mGy), right FFDM(MLO) 1.40 mGy (0.36 mGy, 1.14–1.58 mGy). MGD was significantly higher for DBT mlo views compared to FFDM (p < 0.001). Radiation dose was significantly higher for DBT in MLO views compared to FFDM. However, the MGD of DBT MLO lies below the national diagnostic reference level of 2 mGy for an FFDM view. Hence, our results support the use of either DBT or FFDM as suggested in the ECIBC’s Guidelines.