The effects of pulse pile-up on point-source measurements performed on different PET scanning devices

We have quantified resolution and contrast loss as a function of noise-equivalent count rate on the GSO-based Philips Allegro and the pixelated NaI CPET2 using previously developed methodology involving the NEMA NU 2-2001 70 cm test phantom and a Na-22 point source. We found that at peak NEC, neither system showed significant loss of resolution. However, after accounting for event loss due to dead time, loss of contrast was seen in both systems.