Abstract
1964
Objectives The wide use of SiPM for an extendable scintillation detector module is being accelerated by the recent developments of 4-side tileable SiPM arrays. The aim of this study was to develop a multi-purpose extendable PET detector module using SiPM arrays and evaluate its physical characteristics.
Methods The detector module consists of 4 SiPMs with 4x4 channels (MPPC, 11064-050P) mounted on the resistive charge division network (RCN) for signal multiplexing with an extendable circuit structure. The resistor values of the RCN were determined to match the input impedance from each SiPM channel by using circuit simulation (PSpice). The feasibility of the SiPM detector module was verified by coupling it to various crystal blocks designed for specific purposes, including the MR-compatible PET with/without the use of short optical fibers and DOI PET for animal and breast imaging. For the detector module coupled with single layer 20x18 L0.9GSO crystals (1.5x1.5x7.0 mm3) for PET/MRI, energy, timing, and intrinsic spatial resolutions were measured and temperature dependence and MR compatibility were tested. For the DOI PET systems, 2 different DOI encoding schemes (relative offset method [ROM] and pulse shape discrimination [PSD]) were verified. In the PSD DOI detector, the arrays of L0.9GSO and L0.2GSO crystals with different decay times (τ=40 and 60 ns) were stacked onto the SiPM array.
Results The single layer L0.9GSO detector module yielded an energy resolution of 13.9% and an intrinsic spatial resolution of 1.45 mm. The temperature-dependent gain change was linear between 10°C and 30°C and 3.7%/°C at room temperature. In the DOI detectors, 2 crystal layers were well separated in the flood map (ROM) or the spectrum of early/delayed pulse integration ratio (PSD).
Conclusions The results of this study indicate that the detector modules with multiple SiPM arrays and extendable RCN yielded excellent intrinsic performances for MR-compatible and DOI PET detectors