Document Type: Original Article
Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, Iran
Research Center for Molecular and Cellular Imaging, Tehran University of Medical Sciences, Tehran, Iran
Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran
Introduction: Substantive amount of work has been done in modeling and analyzing the scintillation camera system processes including positioning and image formation. The goal of this work is to develop a framework for analyzing performance of nonlinear positioning methods upon construction of a mathematical model of the system. In this study, the photodetector array counts are assumed to follow a multinomial distribution.
Methods: We studied effects of several parameters on system performance, including photomultiplier tube (PMT) non-uniform response, gains, shape, size and positioning methods. This was done by constructing linearity and resolution maps, feeding the system a uniform grid of point sources showing the distorted output along with associated blurring intensity. The spatial resolution and linearity parameters are used to evaluate the performance of simulated scintillation camera.
Results:The study findings revealed that the square PMT is the best option due to better fitting and quality especially near the edge of the detector and also ability to cover the rectangular crystal area with minimum numbers of PMTs. Also, the resolution resulted from CSE is 5% and 20% better than center of mass and modified center of mass respectively.
Conclusion: We showed that the rectangular gamma camera accompanied by an array of square PMTs can introduce the optimum performance regarding linearity and resolution if the nonlinear method, called CSE, is used as positioning method. Further evaluation is needed to evaluate the performance of the proposed gamma camera in practice.