Comparison of photon counting and conventional scintillation detectors in pinhole SPECT system for small animal imaging

Abstract

The photon counting detector using cadmium telluride (CdTe) or cadmium zinc telluride (CZT) is a promising imaging modality and provides many benefits compared to conventional scintillation detectors. When using the pinhole collimator with the photon counting detector, we are able to improve both spatial resolution and sensitivity. The purpose of this study was to evaluate the photon counting and conventional scintillation detectors in a pinhole single photon emission computed tomography (SPECT) system. We designed five pinhole SPECT systems of two types. One was the CdTe photon counting detector, and the other was the conventional NaI(Tl) scintillation detector. We conducted simulation studies and evaluated the imaging performance. The results showed that the spatial resolution of CdTe photon counting detector was 0.38 mm and the sensitivity in this detector was 1.40 times higher than conventional NaI(Tl) scintillation detector in the same detector thickness condition. Also, the average scatter fraction of the CdTe photon counting and the conventional NaI(Tl) scintillation detectors were 1.93% and 2.44%, respectively. In conclusion, we successfully evaluated various pinhole SPECT systems for small animal imaging.