Computation and parameterization of normalized glandular dose using Geant4

The average absorbed dose in glandular tissue is the most appropriate parameter for the assessment of the radiation-induced risk during breast imaging. The aims of this work concern：（1） the investigation of the variation effect of any related update to photon cross-section data-bases on the computation of the normalized glandular dose（Dg N） for mammography quality control tests and（2） the proposition of a parameterization method leading to provide Dg N values function of the breast thickness（T） and the particle energy（E） instead of E alone, as normally known. We analyzed the change effect of the photon cross-section data-bases on the computation of Dg N. Those coefficients, generated using the Geant4 Monte Carlo toolkit, were studied over a range of compressed breast thickness of 2–8 cm for monoenergetic（1–120 ke V by 1 ke V intervals） and polyenergetic（23–35 k Vp by 2 k Vp intervals） X-ray beams. Moreover, breast tissue composition ranging from about0% glandular（about 100% adipose） to 100% glandular（0% adipose） was also covered. The successful parameterization of Dg N look-up table function of the breast thickness and energy, will compact its analytical form without loss of accuracy. All parameterization fits resulted in r2 values of 0.999 or better.