Establishment of regional Diagnostic Reference Levels (DRLs) for digital mammography in western region of Sri Lanka.

Radiation dose to the breasts should be kept minimum as breast tissues are highly sensitive to radiation. In mammography, the mean glandular dose (MGD) is used to specify the patient dose. In this study, the MGD during diagnostic mammographic examination was collected using the database from six digital mammography facilities available in the western province in Sri Lanka. The examinations with breast pathology, breast implants, compressed breast thicknesses outside 20-110 mm were excluded in this study. The mean MGD per breast was 3.50 mGy with mean Compressed Breast Thickness (CBT) of 57 mm. The mean MGDs per facility is varying from 1.58 to 2.27 mGy, with overall 75th and 95th percentiles of 2.15 and 2.82 mGy, respectively. The 75th and 95th percentiles MGD per image for the average CBT of 57 ± 12 mm were 2.00 mGy and 2.65 mGy respectively. It is suggested to use the 75th percentile value of average CBT for the western region and it was depending on the specific CBT.