Simulation of maximum-likelihood position estimation in small gamma camera with position-sensitive photomultiplier tube (PSPMT)

In the miniature scintillation camera that is composed of a position-sensitive photomultiplier tube (PSPMT) and a scintillation crystal, a computer simulation of maximum-likelihood position estimation (MLPE) for better correction of image than that by a conventional algorithm has been studied. So far MLPE has been proposed in several papers, and mostly experiments finding look-up table (LUT) is necessary to apply this method. In this paper, the MLPE using a simulation method instead of experiments, which can consider all stochastic processes of converting the location of gamma-ray interaction with scintillator into position signals, has been proposed, implemented, and compared to conventional algorithm. From the analysis and comparison of images, the quality of image was better than that of resulting from the conventional algorithm. We verified this simulation method through comparison this simulation images with experimental images using small gamma camera of a NaI(Tl) and a PSPMT. From the result, it is proposed that this simulation method could be applied for all PSPMT with only one simulation instead of every tedious experiment to obtain the LUT for different PSPMT even with the same specification.