A rotating PET camera using BGO block detectors

A positron emission tomography (PET) scanner with a reduced number of detectors per ring subtending two opposing arcs of 60 degrees and mounted on a circular support was developed. Projection data at all angles are acquired by rotating the detector assembly. The scanner has no septa, and data from the equivalent of 16 full rings of detectors are collected and sorted into 256 sinograms. The number of rotational positions at which data must be acquired depends on the size of the field of view (FOV) required. Reconstruction is performed using a fully 3-D reconstruction algorithm. The scanner has an absolute efficiency of 0.5% at the center of the FOV, which is the same as that of a full ring scanner with septa extended. The sensitivity measured with a 20-cm uniform cylinder is 175000 cps/ mu Ci/ml, and the transaxial and axial spatial resolution is the same as for a full ring scanner ( approximately 6 mm). The scatter fraction is 39% with a lower energy threshold at 250 keV. The maximum noise equivalent count rate estimated for a 15-cm-diameter cylinder is 42000 cps at a concentration of 0.5 mu Ci/ml. The camera was used for a number of /sup 18/FDG applications in neurology, cardiology, and oncology.<
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