Characterization of CdZnTe detector for spectral Computed Tomography

The Cadmium Zinc Telluride (CZT) is a room temperature semi-conductor detector with the photon counting capability at a very low X-rays energy and thus can be used for spectral Computed Tomography (CT) imaging. The goal of the study is to characterize the CZT detector for such applications. The device investigated (MXA-128) in this study which comprises of one-twenty-eight pixelated CZT detectors with a pixel dimension of 0.9*0.9 mm2 and a crystal dimension of 16.7*4.4*2.0 mm3. The device is powered by a high voltage module. The power module is adjustable to deliver power from 0 to 1 kVp. The pixelated detectors are arranged in four-pixel array modules with each one containing a linear array digital base board and a read-out module. Each module has 32 channels. Each of these channels can be configured via different channel parameters. The data can be readout in serial mode. The energies of the detected X-ray are recorded and separated in five different energy bins using a 16-bit system. The minimum and maximum X-ray energy detection capability of the detector is 20 and 160 keV respectively. A tungsten anode X-ray source with a power rating from 0 to 35 kVp and a current rating from 0 to 1 mA was used to investigate the detector sensitivity using a conical shaped water phantom having different thickness (range: 29 to 78 mm). The results indicate that the CZT detector is sensitive to the small thickness variation and can be used for both preclinical and clinical spectral CT imaging applications.