Evaluation of patient dose during a digital breast tomosynthesis

When the patient dose in mammography is assessed, it is important to evaluate both average glandular dose (AGD) and entrance surface dose (ESD). A dose survey on both AGD and ESD in mammography has never been studied in Sri Lanka. Therefore, the present study aimed to evaluate the patient dose received during a full-field digital breast tomosynthesis (DBT) examination by determining both AGD and ESD.

The study was performed on 140 patients who underwent DBT examination. The AGD, ESD, compression breast thickness (CBT), half-value layer (HVL), target/filter combination, kVp, and mAs values were obtained from the machine, and AGD for each projection was calculated using the equation proposed by the Dance 2011.

The measured mean AGDs and ESDs of both the breasts were statistically significantly lower than the reference values given by European protocol (p < 0.05). There were no statistically significant differences in both AGDs and ESDs between the right and left breast, between right craniocauidal (RCC) and left craniocaudal (LCC), and between right mediolateral oblique (RMLO) and left mediolateral oblique (LMLO) examinations (p > 0.05). The measured median AGDs and ESDs received for MLO projections of both breasts were statistically significantly higher than that of CC projections (p < 0.05).

The patients receive a low radiation dose during their DBT examination with both lowered AGD and ESD than the recommended values.

The results can be used as a baseline to optimize the radiation dose in mammography in Sri Lanka.