Estimating image quality for future generations of TOF PET scanners

Time-of-flight (TOF) positron emission tomography (PET) scanners produces improved image quality compared to the equivalent non-TOF images, and such improvement is dependent on the scanner time resolution. The present generation of commercial TOF scanners has a time resolution in the range 500-600 ps full width half maximum (FWHM). In this work we investigate how the image quality will improve for future generations of TOF PET. A Geant4 simulation was performed of a 30-cm uniform cylinder containing hot spheres, with time resolution ranging from 600 to 200 ps. Data were reconstructed using TOF FBP, TOF OP-OSEM3D reconstruction, and nonTOF reconstruction as a reference. Images were compared in terms of contrast recovery and the TOF SNR gain was evaluated for both reconstruction methods. The TOF gain was also evaluated vs. count statistics, in order to understand the behavior of such gain at very low counts.