FACTORS AFFECTING SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY (SPECT) WITH A SPECIAL. PROCEDURE APPLIED TO HUMAN BRAIN

Abstract

Single Photon Emission Computed Tomography (SPECT) is a technique for studying the biodistribution radioactive tracers introduced into the body, and provides high­ contrast three-dimensional images. SPECT imaging has a number of potential advantages over conventional nuclear medicine planar imaging. However, special attention is needed, and a SPECT system will not produce adequate results unless very great care is taken in both acquisition and reconstruction of the image. There are whole ranges of acquisition and reconstruction parameters, the change of which will affect the quality of the final image. The present study investigates the various parameters effecting SPECT images and the experimental results demonstrate that; Although uniformity is important in planar images, it is essential to tomographic images. Any borderline nonuniformity in a planar image is magnified many times in the SPECT image and could lead to significant errors in the reconstructed tomographic sections (ring - entire or partial- of high /lower counts in the transaxial images). So, daily uniformity checks and evaluation are essential to ensure that the SPECT system is working properly during the period between one calibration and the next. It's recommended to obtained high-count uniformity calibration images weekly (monthly for a stable system), and after servicing. One of the most important quality control procedures for Tomography is the center of rotation (COR) calibration; the principal behind this calibration is that the center of the camera image must exactly match the center of the computer image when the images' data are reconstructed.