Dose-Saving Potential of Linear- and Non-Linear Energy Weighting in Photon-Counting Spectral Mammography

Abstract

Energy weighting techniques are known to improve the contrast-to-noise (CNR) ratio in energy-sensitive, x-ray photon detection, in particular in the absence of scattered radiation. In spite of the rather moderate reported improvements in CNR, typically ranging between 5-10%, it is of high relevance to quantify the potential for saving radiation dose in a mammography screening environment. In this paper we experimentally investigate the possible improvements to be obtained by energy-weighting of data acquired with a Philips MicroDose SI mammography system. We compare three schemes to combine the raw data consisting of counts registered in the low- and high-energy bins, respectively: conventional summation, linear weighting and non-linear weighting of the two energy bins. Measurements on a dedicated phantom were analyzed to quantify the potential for reduction of patient dose of linear and non-linear energy weighting. By averaging improvements of CNR achieved over several pairs of regions-of-interest (ROI) we report a potential to reduce the patient dose by 7% for linear- and 9% for non-linear energy weighting, in good agreement with expectation.