Performance evaluation of a PET detector witha sparse SiPM array and gap reflectors
WEI Qingyang1,2, WANG Fenhua1, XU Tianpeng3, JIA Chao3, JIANG Nianming3, GU Yu1, MA Tianyu2, LIU Yaqiang2
1. Beijing Engineering Research Center of Industrial Spectrum Imaging, School of Automation and Electrical Engineering, University of Science and Technology Beijing, Beijing 100083, China; 2. Key Laboratory of Particle & Radiation Imaging(Tsinghua University), Ministry of Education, Beijing 100084, China; 3. Beijing Novel Medical Equipment Ltd., Beijing 102206, China
Abstract：Positron emission tomography (PET) usually uses scintillation detectors consisting of crystal arrays and photoelectric sensor arrays. In recent years, silicon photomultipliers (SiPMs) have been more widely used in PET detectors. Although a closely arranged SiPM array can give high performance, a sparse array gives a more cost-effective system. This paper describes a sparse 8×8 SiPM array using the MicroFB-30035-SMT chip from SensL Inc. The array size is 33.7 mm×33.7 mm while the SiPM chip is 3.16 mm×3.16 mm; thus, the gap ratio is 44%. The sparse SiPM array and a dual-layer offset LYSO array were used in a high performance depth PET detector. The gaps between the SiPMs are dead zones which reduce the optical photon collection. Thus, this work studies the effects of adding enhanced spectral reflector films into the gaps. Flood maps were acquired with and without reflectors at room temperature with the crystal response analyzed to find the photopeaks, energy resolution and root-mean square (RMS) of the crystal response. The results show that the reflectors in the gaps effectively enhance the photon collection (25.5% increase) and optimize the energy resolution of the detector (from 13.48% to 12.80%). The quality of the flood map is also improved, i.e. the intrinsic spatial resolution of the PET detector.
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