Evaluation of a SiPM array coupled to a Gd3Al2Ga3O12: Ce (GAGG: Ce) discrete scintillator

Abstract

Purpose: In this study, we present the results of the evaluation of the SensL ArraySL-4 photo-detector, coupled to a 6×6 GAGG:Ce scintillator array, with 2×2×5mm3 crystal size elements for possible applications in medical imaging detectors with focus in PET applications. Experimental evaluation was carried out with 22Na and 137Cs radioactive sources and the parameters studied were energy resolution and peak to valley ratio. Methods: ArraySL-4 is a commercially available, 4×4 array detector covering an active area of 13.4mm2. The GAGG:Ce scintillator array used in this study has 0.1mm thickness BaSO4 reflector material between the crystal elements. A symmetric resistive voltage division matrix was applied, which reduces the 16 outputs of the array to 4 position signals. A Field Programmable Gate Array was used for triggering and digital processing of the signal pulses acquired using free running Analog to Digital Converters. Results: Raw images and horizontal profiles of the 6×6 GAGG:Ce scintillator array produced under 511keV and 662keV excitation are illustrated. Moreover, the energy spectra obtained with 22Na and 137Cs radioactive sources from a single 2×2×5mm3 GAGG:Ce scintillator are shown. The peak to valley ratio and the mean energy resolution values are reported. Conclusions: The acquired raw image of the GAGG:Ce crystal array under 511keV excitation shows a clear visualization of all discrete scintillator elements with a mean peak to valley ratio equal to 40. The mean energy resolution was measured equal to 10.5% and 9% respectively under 511keV and 662keV irradiation. © 2015 Associazione Italiana di Fisica Medica.