Simulation Study on a Stationary SPECT System With Multi-pinhole Collimators

Recently, semiconductor detectors are used to detect gamma rays instead of scintillation detectors in single photon emission CT (SPECT). In these systems, dedicated collimation systems are adopted to reconstruct a myocardium, and data samplings in the reconstruction area are inhomogeneous. This sometimes results in artifacts depending on the size of a patient and location of the myocardium. To avoid these artifacts, we have studied a multi-pinhole SPECT system with a triple head gamma camera. In this paper, we investigated the relationship between the geometrical efficiency of multi-pinhole collimators determined by the diameter of holes and the quality of reconstructed images with Monte Carlo simulations. In these simulations we assumed 19 pinholes and changed the diameter of pinhole collimators; 2, 3, and 5 mm. We calculated projection data with three conditions: a stationary data acquisition with three angular positions, a semi-stationary data acquisition with six angular positions and 12 angular positions over 360 deg. The results of simulations showed that the semi-stationary data acquisition with a small pinhole diameter could reconstruct high quality images.