Abstract
A modified semi-empirical formula that relates the maximum range of the positron to the strength of different magnetic field strengths is developed via Monte Carlo simulation. The formula is derived as an extension to the existing formula of no magnetic field. COMSOL Multiphysics is used to simulate the different physics, including electromagnetic physics and charged particle tracking physics. The Monte Carlo simulation technique by COMSOL is employed to study the effect of magnetic field strength on the positron range PET/MRI scan of the head’s tumor. The magnetic field varies in the range 1–10 Tesla. The simulation code using positron emission is conducted by the Monte Carlo method. Simulation results show that changing the magnetic field affects the particle trajectory and hence the maximum positron range. The elliptic trajectory causes a reduction in displacement between the original location of emission and the location of annihilation, which permits an increased photon emission per unit volume of the tumor and hence a better image resolution. The main contribution of the paper is the formulation of a new semi-empirical relation taking into account the presence of a magnetic field by simulating different particle trajectories for the different magnetic field strengths.