Investigation of silicon photomultipliers for use in preclinical tomographs with BGO arrays

To date most examinations of silicon photomultipliers (SiPM) for use in positron emission tomography have involved studies of arrays or single crystals of Lutetium based scintillators. In this work, we describe measurements bearing on the suitability of SiPMs for use with arrays of pixelated BGO scintillators in preclinical tomographs. Most preclinical scanners rely on photomultiplier tubes (PMTs) coupled to scintillators through a light guide to provide spreading of light over a number of sensor pixels. Because SiPMs have similar gains to PMTs and similar or higher photon detection probability, they could prove an attractive, compact alternative to PMTs for use in preclinical scanners. However, because of the relatively high noise of SiPMs compared to PMTs, combined with the low light output and long decay time of BGO, whether SiPMs can provide an adequate alternative for PMTs in such scanners is an open question. We have examined three commercially available SiPM arrays coupled to a BGO scintillator array. These SiPM sensors are: the Philips digital photon counting SiPM (PDPC), the SensL Matrix9 SiPM array and the Hamamatsu S11828 16 channel Multipixel Photon Counter (MPPC). In particular, we examined the triggering and noise of these devices with respect to the energy and spatial resolution obtained with the BGO array. While we were able to identify the crystals in the BGO array with each sensor, the high noise of these devices when operating at room temperature has a large impact on the energy and spatial resolution. Our results indicate better spatial and energy resolution were obtained with the digital SiPM, which allows suppression of noisy microcells.