An Investigation to Design High Performance Multi-Pinhole

Abstract – The aim of this study is to design a detector module employing multi-pinhole collimator which could be utilized in various SPECT systems. Monte Carlo simulations using Geant4 application for tomographic emission (GATE) were performed to estimate the performance of various multi-pinhole collimators and compared to that of low energy high resolution (LEHR) parallel-hole collimator. The simulated detector module was designed to have 100 mm x 100 mm field of view. In order to determine the optimal number of pinholes, the number of pinholes having 2 mm pinhole diameter and 50 mm focal length was varied from 1 to 225. Perpendicular lead septa were employed to acquire non-overlapping projections and to improve reconstructed image quality. The proposed multi-pinhole detector module was evaluated by the reconstructed images of simulated phantoms. Planar sensitivity and resolution obtained using 81-pinhole collimator were 1.9 cps/µCi and 8.7 mm FWHM at 225 mm distance. 81-pinhole configuration demonstrated better resolution and comparable sensitivity compared to LEHR parallel-hole collimator (2.0 cps/µCi and 10.9 mm FWHM). Multi-pinhole detector module could provide the reconstructed images of 120 mm diameter phantoms without truncation while LEHR parallel-hole detector provided the truncated images. The designed multi-pinhole detector module which could be extended to cover large FOV allows to achieve high quality images even with reduced projection data. I