Investigation of image quality and NEC in a TOF-capable PET scanner

The purpose of this work is to determine the benefit which can be achieved in image quality for a time-of-flight (TOF) capable 3D whole-body PET scanner. We simulate a 3D whole-body time-of-flight PET scanner with a complete modeling of spatial and energy resolutions. The simulated scanner has a diameter of 84-cm, an axial FOV of 25-cm, and uses a 4times4times30-mm³ pixelated LaBr₃ Anger-logic detector. Multiple simulations were performed for a 27-cm diameter and 70-cm long uniform cylinder with hot spheres (22,17,13, and 10-m diameter) in central slice, and 10-mm diameter hot spheres in a slice at 1/4 axial FOV (8:1 activity uptake ratio with respect to background). Image reconstruction was performed with a list-mode iterative TOF algorithm and data were currently analyzed for true coincidences after attenuation correction for timing resolutions of 300,600,1000-ps and non-TOF. Our results show that contrast recovery improves with TOF (NEMA NU2-2001 analysis). Detectability for 10-mm diameter hot spheres estimated using a non-prewhitening matched filter (NPW SNR) also improves with TOF and best results are obtained for timing resolution les300 ps