Adaptive correction of scatter and random events for 3-D backprojected PETdata

Backprojected images offer compact and accurate storage of three-dimensiona l (3-D) positron emission tomography (PET) data and so are potentially very suited to high-resolution 3-D PET scanners. However, there are very few me thods available for correcting backprojected images for the effects of scat ter and random events. Scatter correction methods usually involve experimen tal measurement of scatter response functions or accurate simulations, and are thus limited by the accuracy of the model used. In contrast, the approa ch proposed here uniquely adapts a general form of a combined scatter and r andom response function. This method inherently does not rely upon accurate determination of the scatter and random response functions but does, howev er, rely upon knowledge of the attenuating object's outline. The technique is able to adapt to different imaging situations and account for detector s catter, and in particular is readily implemented in backprojection space. T he method has been implemented for a small-volume HIDAC (II) PET scanner.