Accurately positioning events in a high-resolution PET system that uses 3D CZT detectors

We are investigating the use of cadmium-zinc-telluride (CZT) for high-resolution PET. The 3-D position of individual interactions can be read out from the detector. For the purpose of image reconstruction, an estimate for the first interaction is sufficient. However, it is also desirable for other applications (such as Compton PET, random correction) to sequence the secondary interactions as well. We first compare six basic event positioning algorithms, and then investigate the potential improvement of using a more advanced estimation technique based on the kinematics of Compton scatter.