Monte Carlo simulation of the transit dosimetric response of an a-Si electronic portal imaging device

Amorphous silicon (a-Si) electronic portal imaging devices (EPIDs) are x-ray detectors frequently used in radiotherapy imaging and dosimetry applicatioins. EPIDs employ a copper plate and gadolinium oxysulfide phosphor screen with an array of a-Si photodiodes to indirectly detect incident radiation. In this study, a previously developed Mote Carlo (MC) model of an a-Si EPID has been extended for transit dosimetry.