Feasibility of using cadmium-zinc-telluride detectors in electronically collimated SPECT

Replacing cryogenically cooled germanium (Ge) with room-temperature operable cadmium-zinc-telluride (CZT) semiconducting detectors as the first detector of an electronically collimated SPECT system would have certain practical advantages. To determine the feasibility of this approach, the authors have performed a theoretical study comparing the resolution and sensitivity of a Ge based system to that of a CZT based system. Also, a preliminary experimental study using a 5 mm×5 mm×1.5 mm thick CZT detector as the first detector and an uncollimated scintillation camera as the second detector was conducted to measure the point spread function. The results indicate that the efficiency of a CZT based system would be a factor of 2.5 lower than a comparable Ge based system at 140 keV and the spatial resolution would also be approximately a factor of two worse. However, at higher energies, the difference between CZT and Ge would decrease, and at 662 keV, for example, the CZT and the Ge systems could have nearly equal sensitivity and resolution