Initial experimental studies of using solid-state photomultiplier for PET applications

An evaluation of solid-state photomultiplier (SSPM) has been conducted for Positron Emission Tomography (PET) applications. The single-channel PET detector has been measured for its performance with respect to linearity of light detection, energy resolution, coincidence timing resolution, and depth-of-interaction detection capability. The SSPMs used have a 1×1 mm2 active detection area. At nominal bias, it has a peak sensitivity around 470 nm, typical single photon detection efficiency around 20%, gain about 600,000, dark current 25 μA, and excess noise factor <1.3. A trans-impedance preamplifier was used to read the signal under operating conditions consisted with a balanced energy and timing performance for the PET application. In this initial study, there was a geometry mismatch between the SSPM and LSO crystal with a 2×2 mm2 cross-sectional area, where the light loss could reach 75%. Measured energy and coincidence timing resolutions are 23% and 1.8 ns, respectively, all within the SSPM linear region of photon detection up to ∼250 photoelectrons. The depth-of-interaction (DOI) resolution was measured with two SSPMs detecting lights at both ends of a 1.8×2×20 mm3 LSO crystal, using a conventional electronic collimation method to localize the DOI positions. The measured DOI resolution was 4.5 (+/−0.3) mm, sufficient to develop a PET detector for the measurement of 3D interaction locations. These preliminary measurements have demonstrated the feasibility of using SSPMs for PET applications.