Monte Carlo Modeling of the DQE of a-Se X-Ray Detectors for Breast Imaging.

We study the resolution characteristics of a-Se semiconductor x-ray detectors using ARTEMIS, a detailed Monte Carlo transport code that simulates the three-dimensional spatial and temporal transport of electron-hole pairs under an external electric field. The model takes into account generation and re-absorption of characteristic x rays, spreading due to Compton scattering and high-energy secondary electron transport, and drift and diffusion of electron-hole pairs under applied bias. The point responses for a 200 μm thick mammography detector for RQA radiation qualities are simulated using parallel processing. Line spread functions and modulation transfer functions show a dependence on incident x-ray energy and spatial frequency.