Off-Axis Imaging in Keel-Edge Pinhole Single Photon Emission Computed Tomography System Based on Monte Carlo Simulation

Monte Carlo simulation is applied to investigate the off-axis effect in keel-edge pinhole single photon emission computed tomography imaging. Aiming at finding the effective field of view (FOV) for imaging, we simulate point source in off-axis imaging (0, 4, 8 and 12 mm from the central rotation axis) of different collimator designs (channel height with 1.38, 1 and 0.5 mm) with a fixed aperture diameter. Tradeoff curves of rms resolution and sensitivity are plotted to determine the effective FOV for different channel height pinhole collimators. The parameterized model can be further incorporated into image reconstruction algorithms, which compensates for the off-axis effect and is used as a reference for multi-pinhole design.