Development of a simplified readout for a compact gamma camera based on 2×2 H8500 multi-anode PSPMT array

The aim of this study was to develop a highperformance simplified readout electronic for a compact gamma camera to achieve a maximized performance in its intrinsic spatial resolution. This compact camera is based on a pixellated NaI(Tl) crystal with 1.2 mm×1.2 mm×5 mm pixel element and 1.4 mm pixel pitch coupled to a 2×2 Hamamatsu H8500 multi-anode position sensitive photomultiplier tube (PSPMT) array. The design of the simplified readout is based on novel two-stage charge divisions with Truncated Center-of-Gravity (TCOG) positioning method to maximize the detector performance. The performance of the compact camera with the novel simplified readout was evaluated by flood imaging of a 57Co source. The experimental results show that the readout circuits we developed can effectively reduce the readout channels from 256 to 4 and well resolve the 1.2 mm crystal elements of the NaI(Tl) crystal array while maximizing the effective field-of-view (FOV) of the detector to cover the whole active area of the detector. In addition, the optical coupling measures in the gap regions among the PSPMT array are necessary in order to improve the image distortion in the gap regions. The results indicate that our design is effective approach which can be adopted for other highresolution gamma camera based on multi-anode PSPMT array with a larger FOV.