Study of “A method to enhance coincidence time resolution with applications for medical imaging systems (TOF/PET)”

• The coincidence events by a non-cascade gamma source are described.
• GEANT4 simulations of the cross talk between detectors have been performed.
• The feasibility of the Cs-137 source application for timing studies is explored.

The physics of true coincidence production by the Cs-137 source is elaborated. When the single-photon emitting Cs-137 source is sandwiched between two detectors of a coincidence system, the scattering of 662 keV gamma-rays between the detectors (“cross-talk”) will result in true coincidence events. The results of Ermis et al. (2014) on that issue are critically analyzed. Our Geant-4 simulations did not support most of the results of this work.Thus, the possibility of coincidence time resolution improvement by the Cs-137 source is challenged.