Validation of simulated point response of columnar phosphor screens

摘要

Typical methods to measure the resolution properties of x-ray detectors use slit or edge devices. However, complete models of imaging systems for system optimization require knowledge of the point-response function of the detector. In this paper, we report on the experimental methods developed for the validation of the point-response function of an indirect columnar CsI:Tl detector predicted by Monte Carlo using MANTIS. We describe simulation results that replicate experimental resolution measurements using edge and pinhole devices. The experimental setup consists of a high-resolution CCD camera with a 1-to-1 fiber optic faceplate that allows measurements for different scintillation screens. The results of these experiments and simulations constitute a resource for the development and validation of the columnar models of phosphor screens proposed as part of previous work with MANTIS. We compare experimental high-resolution pinhole responses of two different CsI(Tl) screens to predictions from MANTIS. The simulated response matches reasonably well the measurements at normal and off-normal x-ray incidence angle when a realistic pinhole is used in the simulation geometry. Our results will be combined with results on Swank factors determined from Monte Carlo pulse-height spectra to provide a comprehensive validation of the phosphor models, therefore allowing their use for in silico system optimization.