CdZnTe-Based Photon-Counting Detector Modeling and Calibration for Nondestructive Testing (NDT)

This chapter provides a comprehensive study of cadmium zinc telluride (CdZnTe or CZT)-based photon-counting detectors (PCDs) for nondestructive testing (NDT), and it covers the development, modeling, calibration, and application of these types of detectors. The features of PCDs are showcased as pivotal advancements, offering enhanced diagnostic capabilities, material discrimination, and application versatility across various domains, including medical diagnosis and airport security. The technical details of PCDs, exploring the modeling of X-ray spectra, and the influence of physical phenomena like incomplete photon absorption, beam hardening, finite energy resolution, and charge-sharing events on the detectors’ performance delivered. Different methods for energy calibration are discussed and highlighted, as well as their important role in maintaining PCD accuracy. Techniques ranging from isotope-based baseline calibration to K-edge filters for practical calibration without radioactive sources to kVp calibration for clinical applications are explored, with a presentation of their impact on computed tomography (CT) image reconstruction quality. In the end, we compare PCDs to traditional energy-integrating detectors (EIDs), underlining PCDs’ superior energy resolution, material discrimination capabilities, and diagnostic versatility. This study not only underscores the advancements facilitated by PCD technology but also addresses the challenges and solutions in its implementation, offering insights into future innovations in NDT and related areas.