Industrial gamma computed tomography using high aspect ratio scintillator detectors (A Geant4 simulation)

Gamma-ray Computed Tomography is an important tool for accessing the internal details of large objects in different industries such as oil, gas, petrochemical, etc. In this paper, a Geant4 study was performed to develop a new approach for this type of tomography by using high aspect ratio scintillators. In this method, a NaI(Tl) rectangular cube scintillator, coupled to a PMT on each side in a coincidence setup, was considered as a position sensitive detector. Different responses of the detector including the scintillation processes in presence of 662 keV gamma-rays of a Cs-137 were simulated. Spectral response, position and energy resolutions were obtained and compared to the experimental data. The comparisons showed a good agreement between the simulation results and experimental data. Furthermore, the detector was simulated in a gamma-ray tomography setup and the related projections and cross sectional images of a standard phantom were obtained. The obtained results showed that the high aspect ratio scintillator detector can be used instead of array detector in industrial applications where there is no need to very high position resolutions.