Assessment of Average Glandular Dose Received in Full-field Digital Mammography and Digital Breast Tomosynthesis

Abstract

Objective: To assess the average glandular doses (AGD) from full-field digital mammography (FFDM) and digital breast tomosynthesis (DBT). Material and Methods: Radiographic exposure parameters target/filter, tube voltage, and tube current were collected from 50 patients. Patient information including age, breast thickness, entrance surface air kerma (ESAK) and AGD from the monitor display were also recorded. The tube outputs (tube voltage and tube loadings) at the reference points in both FFDM and DBT modes were measured. The AGD was calculated from ESAK by using the correction factors following the Technical Report Series no. 457 protocol. For the DBT mode, the AGD was calculated and corrected for the X-ray gantry rotation following the Dance et al. method. Results: The radiation doses to breasts in terms of ESAK and AGD from FFDM were 4.97±2.29 and 1.36±0.48 milligray (mGy) respectively. The third quartiles were 6.5 mGy and 1.67 mGy, findings which were lower than the standard Dose Reference Levels reported by the International Atomic Energy Agency recommendation (AGD 3 mGy/view for standard breast thickness with grid). For the DBT mode, ESAK and AGD were 6.49±2.10 mGy and 1.63±0.51 mGy. The third quartiles were 7.68 mGy and 1.81 mGy which were more than the FFDM mode by 23.0% and 17.0%, respectively. Conclusion: This study found that the AGD received from the DBT mode was higher than from the FFDM mode. Patients who underwent combination modes of mammographic examination increasingly received AGD up to 1.74 mGy. However, the AGD in our institute was still lower than the standard AGD recommendations.

Keywords

• average glandular dose
• breast
• digital breast tomosynthesis
• digital full-field mammography
• mammography