FORE(J)+OSEM2D versus OSEM3D reconstruction for large aperture rotating LSO panel detector PET prototype

3D reconstruction on large aperture PET systems based on rotating LSO panel detectors is a challenge due to the large amount of data. When reconstruction time is critical, fast reconstruction methods are attractive despite the potential image quality loss due to rebinning approximation and the large polar aperture angle. This work validates a new data processing suite aimed at processing 3D data for two new PET scanner prototypes using two and five rotating LSO panel detectors, respectively. The processing includes μ-map reconstruction, generation of a 3D attenuation correction, scatter correction and image reconstruction with FORE(J)+OSEM2D and weighted OSEM3D schemes. The validation is based on reconstructing images for simulated wholebody FDG data with realistic random and scatter fractions and given statistics. The same processing suite was applied on experimental data acquired at intermediate statistics on a contrast sphere phantom and on a low statistics FDG wholebody study. Despite the large polar aperture angle, the image quality obtained with FORE(J)+OSEM2D was in excellent agreement with those obtained with time consuming methods such as OSEM3D. The loss in axial resolution from FOREJ to FORE was assessed from noiseless data. We also observed that, on low statistics wholebody data, FOREJ as implemented, required sinogram rebinning and smoothing to control the noise which offsets the benefits of the exact rebinning. The best images in terms of resolution and contrast were obtained with OSEM3D but they required precise normalization and deadtime corrections to avoid ring and banding artifacts.