IMPLEMENTATION AND EVALUATION OF A CALCULATED ATTENUATION CORRECTION FOR PET

A limiting factor in PET is the necessity of a transmission scan for attenuation correction (AC). In areas of uniform attenuation, this measured AC can be replaced by a calculated AC. We present an accurate and efficient method based on estimating the object contour from the emission sinograms. The method relies on a robust algorithm to determine the border between activity and scatter background. In this work, we present an algorithm that has been consistent in finding the object outline for a variety of tracers (F-18-FDG, F-18-FDOPA, O-15-water and N-13-ammonia), extreme uptake distributions (brain tumors and hemispherectomies) and system geometries, with little operator intervention. FDG brain scans using this algorithm were compared to images corrected using measured AC, showing a maximum deviation of +/- 8.9%. The algorithm has been extended to abdominal PET scans and 3-D acquisitions.