Simulations of MeV energy computed tomography

Cross-section images of MeV energy X-ray CT have been simulated with the Monte Carlo method taking into account the flux and energy spectrum of the photons emitted from the X-ray sources. The simulation reveals the theoretical limit of the performance of MeV energy CT systems. The simulated attenuation characteristics, signal-to-noise ratio and the modulation transfer function of the simulated images agree well with the experimental ones, showing the validity of the calculations. The simulation technique allows the image quality of an arbitrary object to be checked with an arbitrary energy source in advance. One of the example simulations presented shows that the CT systems have a theoretical capability to discriminate a density difference of 2-3% in the rotate-only mode as long as the size of an object is within the penetration capability of the X-ray source.