CdZnTe Semiconductor-based Dual Imager Combining Collimatorless and Compton Imaging: Monte Carlo Simulation

Abstract

Compton imaging excels at visualizing gamma rays in the range of several hundred kiloelectronvolts to several megaelectronvolts. However, this technique has limitations in the imaging of low-energy gamma rays. In contrast, collimatorless imaging technique determines the location of a source by analyzing the distribution of interactions. Because the collimatorless imaging technique excels at imaging low-energy gamma rays that are easily shielded by detector components, it can compensate for the shortcomings of the Compton imaging technique. In this study, we propose a dual-mode imaging technique that selects the imaging method depending on the target gamma-ray energy and fuses them during reconstruction. The collimatorless imaging method demonstrated high angular resolution at low energy levels, whereas the Compton image surpasses it starting from 200 keV within its reconstructible range. The angular resolution of the dual-mode image was between those of the two methods. The trend of the positional error of gamma ray energy was similar to that of the angular resolution, and the dual-mode method exhibited the lowest average error of 0.7°. The dual imaging method exhibited higher efficiency, figure of merit, and signal-to-noise ratio by utilizing events from both imaging modalities. In addition, we investigated the geometrical effects of various structures.