Evaluation of image performance of CZT detector for digital mammography: Monte Carlo simulation

Hybrid pixel detector arrays that convert X-ray photons directly into electrical signal are still at the developmental stage for diagnostic X-ray applications. In this work, the feasibility of using CZT detector for application to digital mammography is investigated. In order to evaluate the proposed detection system, a simulation of X-ray photon transport in the sensor material was conducted using the extended version of Monte Carlo N-Particle (MCNPX) code. Charge carrier transport was modelled through the solution of Poissonʹs equation. The two models were then combined in order to evaluate the response of the detector. The line spread function (LSF) was calculated in order to estimate the modulation transfer function (MTF) of the system. CdTe and Si detectors are included for comparison and two different pixel pitches are studied.