Beam-hardening correction method based on original sinogram for X-CT

Beam hardening caused by the polychromatic spectrum is an important problem in X-ray computed tomography (X-CT). It leads to various artifacts in reconstruction images and reduces image quality. A correction method for beam hardening, involving simple operations of the original polychromatic projection sinogram, is here presented based on the analysis of three physics characteristics implied by beam hardening. Its correction principle has been deduced by two mathematical theorems. Excellent correction results have been obtained from computer simulations and CT scan experiments of two phantoms and aero-engine turbine blades. Beam-hardening artifacts are greatly reduced. This method has two outstanding advantages compared with the conventional method with the polynomial fit technique. First, it does not need a prior CT scan and the complex operations to create a correction model. Second, its validity is not limited by the composition of the scanned object and scan conditions.