NON-UNIFORM ATTENUATION AND SCATTER CORRECTION IN SPECT

Using a large test object containing an asymmetrical distribution of Tc-99m activity and having nonuniform attenuation, techniques have been developed and evaluated to correct for attenuation and scatter in the object in conjunction with a filtered backprojection reconstruction algorithm. A weighted-backprojection approach whereby corrections are applied to each pixel from each angle of view was used to correct for attenuation. Using a germanium detector to sample the energy spectrum of emitted radiation, an optimal method was devised to subtract scatter counts from the photopeak counts of a scintillation camera before reconstruction. SPECT (single-photon-emission computed tomography) images of the test object were evaluated to validate the correction approaches.