Beam-hardening in simulated X-ray tomography

Polychromatic X-ray sources are used universally in computerized tomography to obtain adequate intensity of photons. These sources, however, can produce some artifacts in the reconstructed image due to non-linearity. Beam-hardening is one such artifact, which produces false line integrals due the photon-energy dependence of the attenuation co-efficient.The present investigation deals with the process of estimating the equivalent monoenergetic data, mm, from the total attenuation, pp, representing the polyenergetic X-ray beam. Three different specimens are studied which have different geometries.Simulation results show the effect of beam-hardening and its removal (to a reasonable extent) using polynomial approximation method recommended by Herman [J Comput Assist Tomograph 1979;3:373]. The results indicate that the algorithm, proposed originally for medical application applications, is giving encouraging results for non-medical objects though the physical situations are vastly different. Future work with experimental data for non-medical objects is recommended.