SiPM photodetectors for highest time resolution in PET

Abstract

Silicon photomultipliers (SiPM) have a wide range of applications in high energy and medical detector physics. Their excellent timing properties and compactness make them particularly interesting for time of flight positron emission tomography (TOF-PET). This study aims at determining the optimum detector conditions for highest time resolution in a TOF-PET system. The measurements are based on the time over threshold method in a coincidence setup using the ultra-fast amplifier-discriminator NINO and a fast oscilloscope. We compare commercial SiPMs of different SPAD types (Hamamatsu MPPC S10931-025P, S10931-050P and S10931-100P) and production batches. To explore the intrinsic timing capabilities of the SiPM, we coupled short, i.e. 2×2×5mm 3, Ca-co-doped LSO:Ce crystals to the different MPPCs and obtained best results for the 50mm type of 142±4ps FWHM CTR. This performance makes SiPMs ideal candidates for photodetectors in high resolution TOF-PET systems. The results will be discussed in terms of SiPM dark noise and photon detection efficiency (PDE).