Implementation of time-of-flight on CPS HiRez PET scanner

Time-of-flight (TOF) positron emission tomography (PET) was studied and preliminarily developed in the 80s, but the lack of a scintillator able to deliver at the same time proper time resolution and stopping power has prevented this technique from becoming widespread and commercially available. The introduction of LSO in PET has made TOF-PET a feasible option: TOF reconstruction is being implemented in CPS HiRez PET scanner, both in Filtered-Back-Projection and OSEM3D. The measured time resolution of 1.2 ns (FWHM) allows for a signal-to-noise ratio increase of about 50% in patients of about 40 cm transaxial size. TOF reconstruction has shown the expected improvement in SNR, both in simulation and experimental data. In iterative reconstruction we observed that TOF-PET has a much faster convergence compared to conventional reconstruction and better consistency improves the SNR ratio