Monte Carlo simulation for performance evaluation of detector model with a monolithic LaBr3(Ce) crystal and SiPM array for γ radiation imaging

In recent years, LaBr3(Ce) crystals and silicon photomultipliers (SiPMs) have been increasingly used in radiation imaging. This study involved the establishment of a detector model with a monolithic LaBr3(Ce) crystal and SiPM array for gamma-radiation imaging on the GEANT4 platform. The optical process included in the detector model was defined by key parameters, such as the emission spectrum, scintillation yield, and intrinsic resolution of the LaBr3:5% Ce crystal, as well as the detection efficiency of the SiPM array. The response of the detector model to Co-57 flooded field irradiation was simulated and evaluated. The radiation images generated by the detector model exhibited a compression effect that was very close to that on images acquired by the physical detector. The spatial resolution of the simulated detector closely approximates that of the physical experiment. A detector model without the optical process was also established for comparison with a detector using the optical process. Both were used in a near-field modified uniform redundant array (MURA) imaging system to acquire images of a point source and a ring source of Co-57 at the center of the field-of-view of the imaging system. The spatial resolution and signal-to-noise ratio of the images that were reconstructed using the two detector models were determined and compared. Compared with the detector model without optical processes, although the images from the proposed detector model have slightly inferior signal-to-noise ratios and more artifacts, they are more consistent with the reconstructed versions of images acquired in real physical experiments. The results confirm that the detector model can be used to design a gamma-radiation imaging detector and to develop an imaging algorithm that can significantly shorten the development time and reduce the cost.