Investigation of Response of the Pixelated CZT SPECT Imaging System and Comparison with the Conventional SPECT System

PURPOSE: The aim of this study is to investigate the factors affecting the response of the pixelated CZT SPECT imaging systems and to compare the performance of these systems with the conventional SPECT imaging systems. MATERIALS AND METHODS: By using the simulation technique, the effect of applied voltage, gap size between the anode pixels, and electron cloud mobility on the response of a pixelated CZT SPECT system are investigated. Then, the response of this system is compared with the conventional SPECT system in both single- and dual-radioisotope imaging. RESULTS: The results of this study show that increasing the applied voltage, electron cloud mobility or decreasing the gap size, in the optimal range of these parameters obtained in this study, leads to reducing the lateral charge diffusion and consequently improving the probability of the complete charge collection by the target anode pixel. In dual-radioisotope imaging by the pixelated CZT SPECT system, although higher energy resolution results in better separation of photopeaks, the presence of a low-energy tail leads to an overestimation of counts in the low-energy photopeak. CONCLUSION: The use of the optimal values for the applied voltage, gap size, and electron cloud mobility strongly affect the performance of the pixelated CZT SPECT systems. In addition, the presence of a tail restricts the use of these systems for dual-radioisotope imaging and also, the use of the conventional methods for scatter correction.