Beam hardening correction for fan-beam CT imaging with multiple materials

Abstract

In X-ray CT, Beam hardening (BH) effect, which is caused by polychromatic X-ray beam and energy-dependent attenuation coefficients, always introduces cupping and streak artifacts. Most of correction methods can only deal with beam hardening artifacts for a single material or dual-material object, but fail to correct in case of a multi-material object since the correction complexity and instability increase with the increase of the kinds of materials. In this paper, we proposed a multimaterial BH correction method. A binary Legendre polynomial is adopted to correct BH based on bi-parameter imaging physical model, and the Helgasson-Ludwig consistency condition (H-L consistency condition) is introduced to optimally determine the bi-parameters of all materials. In the simulation experiments showed that the proposed method can suppress the artifacts greatly. The corrected values approach very closely to the ideal ones.