Beam Hardening Correction with an Iterative Scheme Using an Exact Backward Projector and a Polychromatic Forward Projector

In computed tomography (CT), reconstructions from conebeam (CB) data acquired with a polychromatic X-ray device show so called beam hardening artifacts. Beam hardening artifacts are highly undesirable for a medical diagnosis, because details in the reconstructed image are severely disturbed or completely lost. In this work, we demonstrate the significant reduction of beam hardening artifacts by using an iterative reconstruction scheme which consists of a backward and a forward projector. For the backward projector, an exact reconstruction approach was used. The forward projector was extended by a polychromatic model to mimic a realistic X-ray device. The presented experiments use simulated CB data to restrict the evaluation to beam hardening artifacts. The discussion is focused on CB data acquired along a helical trajectory.