Modeling of Depth of Interaction with Inter-crystal Scattering for PET Reconstruction

Depth of Interaction (DOI) PET scanners extend the data stored about photon detection events by the depth of the gamma photon's absorption in the detector crystals. Popular DOI-based reconstruction methods disregard photon scattering in the detectors and simply modify the endpoints of the Lines of Responses (LORs). However, such simplification reduces the accuracy of the resulting image. This paper proposes the incorporation of the modeling of inter-crystal scattering into DOI-based PET reconstructions. The transfer probabilities caused by inter-crystal scattering are determined off-line with Monte Carlo simulation and are built into the system matrix as a factored component.