P048] Comparison of breast radiation dose for digital breast tomosynthesis estimated according compressed breast thickness by using breast phatom

Abstract

Purpose To compare the surface radiation dose (ESD) and Average Glandular Dose (AGD) of digital breast tomosynthesis (DBT) examination according compressed breast thickness by using breast phantoms. Methods Because of mammary glands have relatively high radiation sensitivity, that breast dose evaluation for mammography was using entrance surface dose (ESD) and average glandular dose (AGD). Many studies were proven that radiation dose from DBT was higher than that of Digital mammography. The DBT system determines target material, filtration and tube voltage by compressed breast thickness and adjusts to exposure output (mAs) using an automatic exposure control (AEC) system to obtain appropriate image density in clinical practice. An automatic exposure control (AEC) is proposed for ESD and AGD measurement s during DBT exposure. AGD and ESD were estimated using breast phantom thickness categories: 22 mm, 32 mm, 45 mm and 55 mm in clinical practice. Results On DBT examination of 55 mm breast phantom, the mean ESD and AGD were 6.37 mGy and 1.95 mGy, respectively. The mean ESD and AGD values for DBT in 45 mm were 4.32 mGy and 1.43 mGy. The mean ESD and AGD values for DBT in 32 mm were 2.72 mGy and 1.08 mGy. The mean ESD and AGD values for DBT in 22 mm were 1.92 mGy and 0.91 mGy. The ESD was 2–3 times higher compared with the AGD. Conclusions In DBT examination, The ESD and AGD were descending as breast phantom thickness decreases. This study suggests that it is useful for the quality control in DBT examination to mention values of ESD for each breast thickness as well as AGD.