title: Analytical model of coincidence resolving time in TOF-PET.
abstract: The coincidence resolving time (CRT) of scintillation detectors is the parameter determining noise reduction in time-of-flight PET. We derive an analytical CRT model based on the statistical distribution of photons for two different prototype scintillators. For the first one, characterized by single exponential decay, CRT is proportional to the decay time and inversely proportional to the number of photons, with a square root dependence on the trigger level. For the second scintillator prototype, characterized by exponential rise and decay, CRT is proportional to the square root of the product of rise time and decay time divided by the doubled number of photons, and it is nearly independent of the trigger level. This theory is verified by measurements of scintillation time constants, light yield and CRT on scintillator sticks. Trapping effects are taken into account by defining an effective decay time. We show that in terms of signal-to-noise ratio, CRT is as important as patient dose, imaging time or PET system sensitivity. The noise reduction effect of better timing resolution is verified and visualized by Monte Carlo simulation of a NEMA image quality phantom.
authors.affiliation: Philips Research Eindhoven, High Tech Campus 34, 5656 AE Eindhoven, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Wieczorek
authors.forename: A
authors.initials: A
authors.lastname: Thon
authors.forename: T
authors.initials: T
authors.lastname: Dey
authors.forename: V
authors.initials: V
authors.lastname: Khanin
authors.forename: P
authors.initials: P
authors.lastname: Rodnyi
mesh_terms: D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D017785:Photons; D049268:Positron-Emission Tomography / Q000295:instrumentation / Q000379:methods*; D000072232:Radiation Dosimeters / Q000592:standards; D012588:Scintillation Counting / Q000295:instrumentation / Q000379:methods*; D059629:Signal-To-Noise Ratio