Effect of pixel dimensions and thickness on energy resolution and sensitivity of CZT detectors used in nuclear medicine application

Cadmium zinc telluride (CZT) is considered a promising material in detector manufacturing for gamma-ray imaging. The potential of using CZT detectors with pixellated anodes to fulfill the requirements of better spatial and energy resolution as well as higher sensitivity has not been yet fully investigated. Pixellated anodes are advantaged by the small pixel effect but are susceptible to charge sharing and photon scattering within the detector especially in smaller pixel dimensions. In the current work, we combine the finite element method (FEM) and Monte Carlo simulations to model charge transport and photon interactions in the detector. The effect of pixel size on energy resolution and sensitivity was investigated for pixel pitch size from 0.4 up to 1.6 mm and for 5 and 10 mm thickness under 140 and 511 keV photon irradiation.