Ring Artifact on SPECT Image due to Arbitrary Position of PMT Malfunction

Abstract

To obtain high-quality images using SPECT (Single Photon Computed Emission Tomography) imaging, quality control (QC) is required. QC is periodically conducted on SPECT based on standard protocol. Ring artifact are one of the factors in determining optimal image quality. Uniformity is a parameter that determines the ring artifact on SPECT image, which can be appeared as full-ring or half-ring. Those artifacts were generated since one or more PMT (photomultiplier tubes) were malfunctioning. A copper sheet with size of 2 × 2 cm2 and 1 mm thick, attached to LEHR (Low Energy High Resolution) collimator in coordinates (x,y) depending on COR (Center of Rotation) of the gamma camera, was used to generate ring artifact during image acquisition using radioisotope 99