Photon-counting CT (PCCT) is an emerging CT technology that uses photon-counting detectors (PCDs) to
offer better spatial resolution, higher contrast, lower noise, and material-specific imaging as compared to
conventional energy-integrating CT. To study the efficiency and performance of PCCT technologies in
clinical use, virtual imaging trials (VITs) can be used. VITs use computational human phantoms to generate
scanner-specific CT images. The integration of PCCT into VITs requires modeling the signal generation
and signal processing in the detector and electronics, which includes incorporating the effects of nonidealities in PCDs such as crosstalk, charge sharing, and pulse pileup. These non-idealities adversely affect
the image quality of PCCT systems, and their inclusion is important in accurate and realistic modeling of
the PCDs. The existing scanner simulators model either charge sharing or pulse pileup but not their
combined effects. The purpose of this study was to develop an experimentally validated modular detector
response model that accounted for the combined effects of crosstalk, charge sharing, and pulse pileup in
CdTe- and Si-based PCDs. It can be used to simulate variety of PCCT designs, including different detector
materials and geometry, facilitating the evaluation and study of present and future PCCTs. The validation
showed a close agreement with the experimental data acquired using Pixirad-1/Pixie-III PCDs. The
platform was used to generate spatio-energetic covariance correlation matrices that integrated with a VIT
framework called DukeSim to simulate scanner specific PCCT images.
