Abstract
Positron emission tomography (PET) plays a dominant role in nuclear medicine. Due to the extremely high time resolution, the TOF PET technology is valuable clinically. Generally, the SNR could be promoted by Gaussian distribution weighting that means the two photons annihilating position of PET with Time-of-flight information could be located by calculating LOR. Principally, the TOF gain is proportional to the size of the object; however, the scattering photons are also related with the object’s size so that the scatter events will be increasing. Currently the time of flight single scatter simulation (TOF SSS) is usually adopted to remove the scattering events. However, TOF SSS algorithm uses the single scattering quantity of non-TOF to evaluate scaling factor, so it will overestimate the scatter for the both side of tails in TOF bins. We have developed a scatter correction method for 3D PET using beam stopper device. Several stoppers were placed surrounding the object to attenuate primary events. The object was scanned twice (with and w/o BS), and the information of acquisition could accurately calculate the amount of the total scatter of the object. In this work, we extended the BS method to correct scatter events in TOF PET. Owing to each TOF bins with different scatter distribution and scatter ratio in TOF PET imaging, the TOF BS method could correct it for the different scatter properties of TOF bin. The Monte Carlo simulation is performed to study the proposed method using two digital phantoms. The corrected effect of the images reconstructed by TOF MLEM algorithm was evaluated using contrast, CV, and MSE parameters. The preliminary result showed that the proposed method is better than TOF SSS on contrast and MSE of images. The proposed TOF BS method could be a feasible way to correct scattered events and it will be applied in clinic experiment in our future work.