P010] Radiation dose levels in digital mammography: A retrospective review in a South American imaging centre

Abstract

Purpose To present results of a retrospective data analysis carried out at a large academic medical centre in South America and to establish a dose reference level (DRL) for digital mammography studies in the region. Methods All patients presenting for screening mammography between July 1 and December 30, 2017 at our imaging centre were reviewed in this study, for which the institutional review board granted approval and waived the requirement for informed consent. Technical parameters including breast compression force, compressed breast thickness, mean glandular dose (MGD), and the number of views needed for complete breast coverage were recorded and analysed. Results A total of 2492 images acquired from 623 patients with a Siemens Mammomat Inspiration digital mammography system were included. The MGD per examination was 2.88 ± 0.05 mGy, the average compressed breast thickness was 64.3 ± 0.5 mm, and the average compression force was 10.1 ± 0.4dN. Twelve percent of the cases required more than the four normal views to cover all breast tissue. When extra views were included, the MGD per subject was 3.85 ± 0.06 mGy. A DRL value of 1.64 mGy has been established by calculating the 95 th percentile of the average MGD for compressed thicknesses ranging from 55 mm to 64 mm. Conclusions Our results show that demographic factors including mean breast thickness and breast prosthesis affect MGD of patients in our region. Finally, our findings show a modest increase of radiation dose to the breast by digital mammography due to the average breast thickness of our patients.