PET transmission scanning with a variable speed orbiting rod source

The authors have constructed a model which makes it possible to simulate the action of a variable-speed ORS (orbiting rod source) and to form variance sinograms for attenuation-corrected emission scans. The variance sinograms are then reconstructed and image variance estimates are obtained. Simulated results from the GE 2048 PET (positron emission tomography) scanner and experimental results form the GE Advance scanner were used to verify the model. It is shown that for noncircular objects the variance at the image center can be reduced by adopting a variable speed source orbit. In simulation, images derived from attenuation-corrected emission data also demonstrated improved uniformity. In experiment, the statistical uniformity of the variable speed ORS was improved in some areas of centralized anatomy while not in others