Performance characterization of a Compton camera prototype based on a novel epitaxial-quenching-resistor SiPM

Abstract A Compton camera prototype was developed and characterized, utilizing a novel epitaxial-quenching-resistor Silicon Photomultiplier (EQR SiPM). The SiPM, with dimensions of 3.75 × 3.55 mm 2 and an effective area of 3.00 × 3.00 mm 2 , was configured into a 6 × 6 array. The array, with horizontal and vertical spacings of 0.58 mm and 0.82 mm respectively, formed a total size of 25.4 × 25.4 mm 2 . Both the scatterer and absorber were constructed from identical Lutetium-yttrium oxyorthosilicate (LYSO) crystal arrays, each comprising 24 × 24 crystals with dimensions of 0.98 × 0.98 × 10 mm 3 in 1.0 mm pitch. Coincidence events were acquired using an 8-channel data acquisition card (DAQ). Image reconstruction was performed using a filtered back-projection (FBP) algorithm with a Shepp-Logan filter, optimized for multi-graphics processing units (GPUs) processing. Calibration results demonstrated an energy resolution (Full Width at Half Maximum, FWHM) of 11.89% at 662 keV. Imaging experiments with a point source yielded an angular resolution of 8.95° (FWHM) at a scatterer-to-absorber distance of 50 mm. Additionally, successful imaging of a V-shaped tubing phantom confirmed the system's ability to accurately image distributed sources. The study also investigated how angular resolution and detection efficiency change with varying distances between the two detector layers. The results from Monte Carlo simulations demonstrated the system's ability to simultaneously image two distinct sources. Furthermore, the findings suggest that the current system's energy resolution is the main factor constraining the overall angular resolution. Future work will focus on optimizing the system design, including studying the effects of temperature and bias on SiPM gain, to enhance the camera's performance for various applications.