INSTITUTIONAL BREAST DOSES IN DIGITAL MAMMOGRAPHY.

Abstract

The objective of this study was to survey breast dose in screening mammography, establish institutional doses and compare them with the corresponding dose values. Three hundred women between the ages of 40 and 80 years old participated in the study. All mammographic examinations were performed with a digital mammography system. The women characteristics (age, weight, height, BMI), technical and exposure parameters (anode/filter material, projection, compressed breast thickness (CBT), compression force, tube voltage, tube load), the entrance surface dose (ESD) and the average glandular dose (AGD) were recorded. The mean, median, 75th and 95th percentiles of the AGD and ESD distributions were estimated for all examinations, for right and left breast, as well as for CBT within 55-65 mm, for Cranio-Caudal (CC) and Medio-Lateral Oblique (MLO) projections. A statistical analysis was also performed, to investigate the impact of the recorded parameters on the ESD and AGD. The mean/median values of the ESD and AGD for all examinations, for CC and MLO projections were 4.60/4.29 and 5.42/5.25 mGy and 1.18/1.13 and 1.32/1.30 mGy, respectively. The mean/median values of the ESD and AGD for CC and MLO projections at CBT range 55-65 mm were 5.29/5.08 and 5.56/5.42 mGy and 1.30/1.24 and 1.36/1.32 mGy, respectively. The 75th percentile for CC and MLO projections were estimated 5.79 and 6.17 mGy, as well as 1.41 and 1.48 mGy in terms of ESD and AGD values, respectively. The 95th percentile of the ESD and AGD for CC and MLO projections were also 7.40 and 7.53 mGy and 1.76 and 1.78 mGy, respectively. The tube voltage, tube load, age and CBT had a significant influence on the dose values. The estimated values were found to be comparable, or in most cases lower, than the corresponding 75th and 95th percentile values from previous studies.