Performance Characteristics of a Dual-Sided Position-Sensitive Sparse-Sensor Detector for Gamma-Ray Imaging

Purpose: We characterize the performance of a dual-sided position-sensitive sparse-sensor (DS-PS3) array detector for positron emission tomography (PET). The DS-PS3 detector is designed as a high performance, cost-effective PET detector for organ-specific imaging systems (e.g., brain, breast, etc.). Methods: Two sparse 4-by-4 arrays of silicon photomultipliers (18.5% SiPM fill factor) coupled through segmented light guide are used to readout a 15-by-15 array of 2-mm-pitch, 20-mm-long LSYO crystals. Uniform flood data were used for crystal identification, depth determination, and position-dependent energy resolution. Intrinsic-spatial and depth-of-interaction (DOI) resolutions were determined by stepping a collimated gamma-ray source over the front and side, respectively. Results: We measured an average intrinsic spatial resolution of 2.14 ± 0.07 mm full width at half maximum (FWHM). DOI FWHM resolution varied from 2.2 mm for crystals over sensors to 5.3 mm for crystals between sensors. Average DOI resolution was 3.6 ± 0.8 mm FHWM. Average energy resolution for the detector module was 16.6% with a range of 11.3%–25.8%. Conclusions: We have demonstrated the use of a dual-sided sparse sensor array to enable low-cost high-performance decoding of 3-D positioning within a PET detector using an 18.5% sensor fill factor.