Initial results on SiPM performance for use in medical imaging

Silicon Photomultiplier (SiPM) detectors are attractive canditades for the replacement of Photomultipliers in nuclear imaging. They are compact, provide high gain with low V_bias and have fast response. In addition, SiPMs are not influenced by strong magnetic fields, allowing the use in the emerging field of PET-MRI. The development of small prototypes based on SiPMs posses several design challenges, since it is necessary to optimize scintillator and SiPM coupling, as well as signal amplification and digitization. In this work, we investigated the performance of 3 simple SiPM modules constructed by SensL corporation coupled on various scintillator detectors, suitable for SPECT and PET systems. ^99mTc, ¹¹¹In and ¹⁸F were used. The readout system includes the SensL preamplifier circuit, a nuclear imaging module (NIM) amplifier and analog to digital converter (ADC) controlled by MPA/WIN (Multiparameter Analyser) software. The parameters that have been measured are: output pulse shape, dark count rate (DCR), detection efficiency, linearity and energy resolution for different bias voltages (V_bias) and photon energies. Best energy resolution was experimentally measured 11% for 511keV and 23% for 140keV. V_bias applied on SiPMs strongly affects output pulse amplitude and depends on the SiPM characteristics.