Optimization of 3D TOF PET reconstruction using a limited number of 2D histoprojections

The next generation human PET scanners will possess the capability to measure the time-of-flight (TOF) information due to the availability of faster scintillators like LaBr₃ and LSO. These systems will be able to measure timing resolutions well below 1 ns. The shorter point spread function (compared to conventional PET) allows reconstruction from fewer angles. We show that with improved TOF-resolution, the number of angles needed to obtain artifact free reconstruction decreases with improving TOF resolution. In a ring scanner this property can be exploited by mashing the data from adjacent angles using the TOF information. Based on the angular sampling criterion for PET we propose an angular sampling criterion for TOF-PET. Simulated data of 2D TOF-PET systems were reconstructed from a varying number of angles with iterative reconstruction. The comparison with the listmode reconstruction confirmed the predicted relationship. Simulated 3D TOF-PET data were rebinned into a 2D data. The relationship between the number of angles and the TOF resolution also determines the maximum axial acceptance angle where rebinning can be done without contrast loss. The angular sampling criterion for TOF-PET can will be useful to determine the number of mashing angles and axial tilts for a certain timing resolution