PeneloPET simulations of the Biograph ToF clinical PET scanner

Monte Carlo simulations are widely used in positron emission tomography (PET) for optimizing detector design, acquisition protocols, as well as for developing and assessing corrections and reconstruction methods. PeneloPET is a Monte Carlo code for PET simulations which considers detector geometry, acquisition electronics and materials, and source definitions. PeneloPET is based on PENELOPE, a Monte Carlo code for the simulation of the transport in matter of electrons, positrons and photons, with energies up to 1 GeV. In this work we use PeneloPET to simulate the Biograph TruePoint (B-TP), Biograph TruePoint with TrueV (B-TPTV) and Biograph mCT PET/CT scanners. These configurations consist of three (B-TP) and four (B-TPTV and mCT) rings of 48 detector blocks. Each block comprises a 13 × 13 matrix of 4 × 4 × 20 mm³ LSO crystals. Simulations were adjusted to reproduce some experimental results from the actual scanners and validated by comparing their predictions to further experimental results. Sensitivity, spatial resolution, noise equivalent count (NEC) rate and scatter fraction (SF) were estimated. The simulations were then employed to estimate the optimum values of system parameters, such as energy and time coincidence windows and to assess the effect of system modifications (such as number of rings) on performance.