Monte Carlo simulation of a TOF PET scanner. I. Preliminary report

A Monte Carlo simulation was developed to study scattered radiation in the SP3000 (Scanditronix/PETT) time-of-flight (TOF) positron emission tomography (PET) scanner. The simulation was based on MCNP, a general-purpose radiation transport code, which was modified for requirements specific to PET and the SP3000: camera wobble, collinear 0.511-MeV annihilation source photons, and coincidence detection. Two detector rings, 640 detectors, of the SP3000 were modeled using MCNP's geometry description language, thus simulating one cross and two straight image planes. For each coincidence, information regarding the scattering of the detected photons was maintained. Good agreement of measured and simulated coincidence sensitivities, energy spectra, and scatter fraction provided strong evidence that the simulation was accurate. Simulation of a distributed source in a 22-cm-diameter water-filled Lucite cylinder indicates that the majority of scattered coincidences originate from photon scattering in the camera.<
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