SILICON PHOTOMULTIPLIERS FOR MEDICAL IMAGING AND DOSIMETRY-AN OVERVIEW

Silicon photomultipliers (SiPMs) are an enabling solid-state technology for low light sensing, with single photon sensitivity and photon number resolving capability. They feature an extremely high internal gain at the 10(6) level, comparable to photomultiplier tubes (PMTs), with the advantage of low operating voltage (~50 V compared to ~1000 V for PMT) and low energy consumption. The solid-state technology makes SiPMs compact, insensitive to magnetic fields and with an extreme flexibility in the design to cope with different applications. The fast development of the multiplication avalanche opens up the possibility to achieve time resolution at the 30 ps level. Dynamic range is however limited compared to PMT and the dark count rate relatively high, yet today at the level of 50 kHz/mm(2) at room temperature. Interfaced with scintillation material, SiPMs provide a powerful platform for medical imaging applications (in positron emission tomography/computed tomography and in positron emission tomography/magnetic resonance), for X-ray quality control as well as for novel compact radiation protection instruments. This article gives an overview of SiPMs for medical imaging and dosimetry. In addition, a learning and training program targeted to graduate students is described.