Additional factors for the estimation of mean glandular breast dose using the UK mammography dosimetry protocol

TLDR

The UK and European mammographic dosimetry protocols use conversion factors that relate incident air kerma to mean glandular dose (MGD) within the breast. The authors derived conversion factors via computer simulation of a 50/50 adipose–glandular breast model, extended the data to 11‑cm compressed thickness, and provided tables of typical breast glandularities for women aged 40–49 and 50–64 and for thicknesses 2–11 cm, as well as equivalent PMMA thickness tables for dosimetric simulation. Relative conversion factors were calculated that extend the protocols to breasts of varying glandularity and a wider range of mammographic x‑ray spectra.

Abstract

The UK and European protocols for mammographic dosimetry use conversion factors that relate incident air kerma to the mean glandular dose (MGD) within the breast. The conversion factors currently used were obtained by computer simulation of a model breast with a composition of 50% adipose and 50% glandular tissues by weight (50% glandularity). Relative conversion factors have been calculated which allow the extension of the protocols to breasts of varying glandularity and for a wider range of mammographic x-ray spectra. The data have also been extended to breasts of a compressed thickness of 11 cm. To facilitate the calculation of MGD in patient surveys, typical breast glandularities are tabulated for women in the age ranges 40-49 and 50-64 years, and for breasts in the thickness range 2-11 cm. In addition, tables of equivalent thickness of polymethyl methacrylate have been provided to allow the simulation for dosimetric purposes of typical breasts of various thicknesses.