Evaluation and benchmarking of a commercial cadmium zinc telluride (CZT) gamma imaging camera

We have assessed the efficacy and application of a commercially manufactured cadmium zinc telluride (CZT) gamma imaging camera. The imaging system manufactured by H3D Corporation (Ann Arbor, Michigan) is intended for practical field applications by first responders and nuclear power plant surveyors. The H3D imager (Model H420) uses a position-sensitive, pixelated CZT element <19 cm3 in volume with gamma energy resolution of <1.1% FWHM at a reference gamma energy of Cs-137 (662 keV) to develop fast (less than 2 minutes start-up time), lightweight (8.6 lb) gamma imaging systems. The Model H420 gamma imager’s automated mask/anti-mask uses a rank-19 coded aperture mask for improved signal-to-noise ratio and cleaner images; it also benefits from the Compton imaging technique. Options for better quality CZT crystals with ≤0.8% FWHM resolution at 662 keV are available. The system’s integrated range finder can precisely overlay gamma ray and optical images from point-like or extended gamma emitting sources alike, which can show the extent of a radiological spill. The CZT imager enhances the surveillance capability of the first responders in targeted search and radiological emergency response. Comparative in-depth references will be made to the progress made since the original concept of applying 3D, position-sensitive, pixelated CZT in the area of materials development (crystal growth techniques), detector mounting, electronic readout of the application-specific integrated circuits (ASICS), event reconstruction algorithm, calibration procedures, and noise reduction techniques to imaging.