Performance evaluation of SiPM photodetectors for PET imaging in the presence of magnetic fields

The multi pixel photon counter (MPPC) or silicon photomultiplier (SiPM), recently introduced as a solid state photodetector, consists of an array of Geiger mode photodiodes (microcells). It is a promising device for PET due to its potential for high photon detection efficiency (PDE) and its foreseeable immunity to magnetic fields. It is also easy to use with simple read outs, has a high gain and a small size. In this work we evaluate the in field performance of three 1x1mm2 (with 100, 400 and 1600 microcells, respectively) and one 6x6mm2 (arranged as a 2x2 array) Hamamatsu MPPCs for their use in PET imaging. We examine the dependence of the energy resolution and the gain of these devices on the temperature and reverse bias voltage, when coupled to LYSO scintillator crystals under conditions that one would find in a PET system. We find that the 400 and 1600 microcells models and the 2x2 array are suitable for small size crystals, like those employed in high resolution small animal scanners. We have confirmed the good performance of these devices up to magnetic fields of 7 T as well as their suitability for performing PET acquisitions in the presence of fast switching gradients and high duty radiofrequency MRI sequencesThis work was supported in part by the CDTEAM project of the CENIT program, and by Ministerio de Ciencia e Innovacio´n under projects FPA2007 62216TEC2008 06715 C02 01, UCM (Grupos UCM; 910059), CPAN (Consolider Ingenio 2010) CSPD 2007 00042 projects, and project SENSORCZT S 0505/MAT/000279, Comunidad de Madrid. Part of the computations of this work were done at the ‘‘High Capacity Cluster for Physical Techniques’’ of UCM, funded in part by the UE under the FEDER program and in part by UCMPublicad