Real-Time Accurate Rebinning of PET Data Based on the Pseudo-Inverse of the Axial System Matrix

Real-time Positron Emission Tomography (PET) has the potential to become a new imaging tool providing useful information, such as first-shot images, medical interventions guidance, information about patient position and motion, and feedback during acquisition. Fully-3D iterative reconstruction methods in PET provide accurate results, but they cannot be used for real time imaging due to their long computational time. On the other hand, analytical methods are fast enough for real time applications, but they exhibit poor resolution and artifacts with noisy or incomplete data. We propose an alternative reconstruction method based on the pseudoinverse of the System Response Matrices (SRM), which can be fast and accurate. Due to the large size of the SRM, instead of pseudo inverting the fully 3D-SRM, only the axial part of the SRM is pseudoinverted and used to rebin the 3D data into 2D datasets with accurate resolution recovery in the axial direction. The resulting rebinned 2D datasets can be reconstructed with standard analytical methods such as Filtered Back-Projection (FBP), or another in-plane pseudoinverse. Our results provide better results than the standard Single Slice ReBinning (SSRB), and with computational time compatible with real-time applications.