Monte Carlo Based Estimation of Weight Functions for Few-View Computed Tomography of Strongly Absorbing Objects

The paper offers a method to simulate weight functions for few-view X-ray computed tomography of strongly absorbing objects. The method is based on a probabilistic interpretation of energy transport through the object from a source to a detector. Photons are tracked with a PRIZMA code package that is developed at RFNC-VNIITF and implements a stochastic Monte Carlo method. The value of the weight function in a discrete cell of the reconstruction region is assumed to be directly proportional to the fraction of photon trajectories which cross the cell from all those recorded by the detector. The efficiency of the method is validated through a numerical experiment aimed to reconstruct a section of a spherical heavy metal phantom with an air cavity and a density difference of 25%. The method proposed for weight function calculation is shown to outperform the method based on projection approximation in case of reconstruction from 9 views.