A Monte Carlo simulation study on effects of energy weighted dual-energy subtraction images with indirect photon-counting detector in mammography

Abstract

The purpose of this study is to design an indirect photon-counting detector using a GAGG scintillator with Monte Carlo simulation and to evaluate the efficacy of the result using an energy weighted subtraction method. Factors to validate the efficacy of energy weighted subtraction were the type of scintillator and the profile of the x-ray spectrum. Images were obtained using GAGG and CsI scintillators with incident x-ray spectra split from continuous x-rays and were processed using energy weighted subtraction and energy subtraction. The composition of the phantom for image acquisition consisted of calcium embedded in the breast tissue, and the phantom images were analyzed by comparing the contrast-to-noise ratio (CNR). Based on the simulation results, GAGG demonstrates improved CNR compared to CsI, and the energy weighted subtraction method yields similar or higher CNR values compared to the energy subtraction method except in the case of using the CsI detector in a continuous x-ray spectrum. Moreover, the CNR values were higher for split x-rays than for continuous x-rays. In conclusion, GAGG detectors, the energy weighted subtraction method, and a split spectrum can be used to enhance the contrast of images while augmenting the fine calcification of simulated breast images. K: X-ray mammography and scinto-and MRI-mammography; X-ray radiography and digital radiography (DR)