Diagnostic reference levels (DRLs) in digital mammography in the European context – a systematic review

Abstract This systematic review examines the establishment of Diagnostic Reference Levels (DRLs) in digital mammography across 18 European countries, based on studies from 2005-2025. A total of 353 articles were identified through the comprehensive search of academic networks: Google Scholar, PubMed, Research Gate, Academia. Only 18 peer-reviewed studies met inclusion criteria – reporting Mean Glandular Dose (MGD)-based DRLs from Finland to Malta. Eight studies used patient data, four used phantom measurements, and six used both. To overcome the challenging comparison of the variety of reported parameters, we undertook some data harmonisation procedures, focusing on a common Compressed Breast Thickness (CBT) range of 50-59 mm. The DRLs varied notably by country, with 75 th percentile MGDs ranging from 1.1 to 2.6 mGy and 95 th percentile from 1.6 to 2.9 mGy, averaging to 1.44 mGy, which is lower than the achievable European level (2 mGy). The harmonisation approach enabled the derivation of a comparable dataset of average MGDs, facilitating cross-country comparisons and insights into radiation dose optimisation in digital mammography across Europe.