This work is aimed at developing a compact gamma camera module of high spatial resolution

based on block scintillation crystal coupling with position sensitive photomultiplier (PSPMT).Monte Carlo simulation was used to study the shrinkage effect and intrinsic spatial resolution of miniature gamma camera module with crystal parameters.The readout electronics and the position determination method of the PSPMT were improved by using a novel truncated center-of-gravity method.Imaging experiments were performed to evaluate our design.The results demonstrate that readout circuit with truncated center-of-gravity (TCOG) can restrict the shrinkage effect;the spatial resolution and shrinkage effect of crystal are improved with reduced thickness and increased light output.It can be concluded that a crystal wafer coupled to PSPMT will have 1-2 mm intrinsic resolution

hence a high cost-effective solution compared to crystal array design.