Improving Pet Scanner Time-of-Flightresolution Using Additional Prompt Photon

Positronium Imaging requires two classes of events: double-coincidences originated from pair ofback-to-back annihilation photons and triple-coincidences comprised with two annihilation photonsand one additional prompt photon. The standard reconstruction of the emission position along theline-of-response of triple-coincidence event is the same as in the case of double-coincidence event;an information introduced by the high-energetic prompt photon is ignored. In this study, we proposeto extend the reconstruction of position of triple-coincidence event by taking into account the timeand position of prompt photon. We incorporate the knowledge about the positronium lifetime distributionand discuss the limitations of the method based on the simulation data. We highlight that theuncertainty of the estimate provided by prompt photon alone is much higher than the standard deviationestimated based on two annihilation photons. We finally demonstrate the extent of resolutionimprovement that can be obtained when estimated using three photons.