Microdosimetric characterisation of 28 kV(p) Mo/Mo, Rh/Rh, Rh/Al, W/Rh and Mo/Rh mammography X ray spectra

Abstract

Microdosimetric characteristics of 28 kV(p), mammography X ray spectra were studied for several target/added filtration combinations (Mo/Mo, Rh/Rh, Rh/Al, W/Rh, Mo/Rh). Monte Carlo techniques were used to model X ray production from mammography units and to calculate distributions of absorbed dose and energy imparted in breast tissue The results show that the dose averaged lineal energy is about 5.0 keV.mum(-1). about 25% higher than for general diagnostic imaging X ray spectra. Significant differences in lineal energy between the five X ray qualities were noted, with the highest value for the commonly used Mo/Mo combination, Spectral hardening with depth in the tissues causes a 5% decrease in lineal energy over 5 cm. No significant differences ere found for the different (issue compositions.