Computational simulations of the influence of angular rotation deviations in optical CT imaging of gel dosimeters

Two types of angular rotation deviations are observed in our optical CT scanner for gel dosimetry: a large deviation at the starting position, and small deviations during the scanning. In order to investigate the influence of these angular rotation deviations on the reconstructed OD maps, we applied the angular deviations on a synthetic phantom for optical CT simulation. Meanwhile, three reconstruction schemes are proposed for compensation. The simulation results show that the influence of both types of rotation deviation is as small as less than 1% over the central reconstruction phantom region. Based on the reconstructed results via different methods, we can conclude: 1) reconstruction with the regridded projections can better decrease the errors caused by the large angle deviation; 2) for small angle deviations, reconstruction with actual-angle compensation delivers less pronounced results; 3) for real cases, the hybrid approach is shown to reduce reconstruction errors.