Simulation of polychromatic x-ray transmission computed tomography process with tungsten-anode source and varying source filter thickness

Abstract

A first-generation parallel-beam computed tomography setup with polychromatic tungsten-anode x-ray source was simulated by modelling the process as a superposition of many monochromatic CT processes happening simultaneously. This was done by binning the source's 90-keV energy range into 1800 energy bins and choosing the left bin edge as the representative monochromatic energy for the bin. A digital phantom of an acrylic box with five aluminum rods was used for the simulations. The linear attenuation coefficients of acrylic and aluminum for each representative energy were obtained from the National Institute of Standards and Technology XCOM Database. A monochromatic CT simulation using the tungsten peak at  was also done for reconstruction comparisons. The monochromatic CT reconstruction shows the homogeneity of the box and the rods while the polychromatic CT reconstructions show these as non-homogeneous. Edges of the outer rods also appeared denser as a result of beam hardening in the polychromatic case.