System performance of a hexagonal bar positron camera

The performance of the hexagonal bar positron camera has been evaluated for a variety of applications. This single-slice whole-body scanner has six continuous NaI(Tl) detectors, which remain stationary during data acquisition. Each detector has a spatial resolution of 6.0 mm at low data rates, although an improved resolution of 4.0 mm has been demonstrated with certain modifications. The measured resolution in the reconstructed image is 6.5 mm FWHM, which is independent of the distance from the center of the patient port. At a high countrate of 200 K singles, which is encountered with Rb-82 imaging, the image resolution is 7.5 mm. Before an image is reconstructed, the nonlinearities associated with continuous detectors are corrected. The data are rebinned into a sinogram and then normalized. The gaps between the detectors result in a 10% loss of data. Because of the missing data, a filtered backprojection with interpolation of the data across the gaps results in artifacts in images of extended objects. The authors therefore use a maximum likelihood iterative algorithm based on that of a previous study. Images of the Derenzo phantom and the Hoffman brain phantom do not have noticeable artifacts using this algorithm. In addition to the phantom studies, the authors have imaged human brains with F-18 deoxyglucose and dog hearts with generator produced Rb-82