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内容記述 |
[Purpose] Whole gamma imaging (WG) can image both positron emitters and single-gamma emitters simultaneously by hybrid PET-Compton imaging capability. In addition, even when only one of an annihilation gamma-ray pair of a positron emitter is detected, it can be detected as a Compton event and has the potential to improve PET image quality. In this study, we develop a synergistic image reconstruction algorithm that uses Compton and PET images synergistically and investigate the possibility of improving both image quality. Especially, Compton imaging for 511 keV photons in current WGI prototypes inferior to PET due to their energy resolution. Therefore, we investigated whether it is possible to improve PET by adding inferior information of Compton imaging.[Methods] We defined an energy function describing the relationship between PET and Compton images as prior information, and we synergistically integrate it into both image reconstruction processes to obtain both PET and Compton images separately in three alternating steps. First, PET image was reconstructed using the maximum a posteriori expectation maximization (MAPEM) algorithm. Second, Compton image was reconstructed using the MAPEM algorithm. Finally, the energy function for the correlations between PET and Compton images was updated. These steps were iteratively performed. We evaluated the proposed synergistic image reconstruction method using Monte Carolo Simulation data of a WGI system and compared the reconstructed images with the OSEM algorithm.[Results] Comparison of tradeoff curves of spatial resolution and noise suggested that the proposed reconstruction method could push the limit of spatial resolution while reducing statistical noise compared with the OSEM algorithm.[Conclusion] PET image quality could be improved by adding inferior Compton imaging data in WGI for positron emitters. |
