Beam hardening correction using an attenuation coefficient decomposition approach

In X-ray CT system, the X-ray source generates x-rays with a broad range of spectrum. When the polychromatic photons travel through a subject, the lower energy photons are attenuated more effectively than the higher energy ones. This causes different attenuation coefficient (AC) of the material with respect to different X-ray photon energy. The reconstruction algorithms assuming invariant A C will introduce beam hardening artifacts in the reconstructed images. One effective method to address this is to model the X-ray attenuation process during the reconstruction. Generally an objective function is derived and an iterative method is used to minimize the objective function. This can be very time-consuming, and meanwhile it is relatively more difficult to compute such iterative algorithms in parallel. This work introduces an approach that uses an intermediate step to reduce the beam hardening artifacts. Due to the independence between the computation for each projection, it has the advantage of being able to compute in parallel.