A Non-iterative Data-driven Beam Hardening Correction for Single-material Objects 135

In industrial X-ray CT application, it is particularly important to remove beam hardening artifacts in reconstructed images in order to achieve accurate surface extraction for dimensional inspection of mechanical parts. This paper proposes a new method in the same category as the IAR (iterative artifact reduction) technique with the added advantage of not requiring repeated image reconstruction. In general, beam hardening artifacts are basically reduced to create a non-linear characteristic curve representing the relationship between the projection value and the transmission length of the ray. In the proposed approach, this curve is based on the property that the sum of the transmission lengths must be preserved for all projection angles (views) – a characteristic known as the volume conservation corollary of the Radon transform. Solving an optimization problem for determining the characteristic curve based on this property is very little overhead of the ordinary CT reconstruction.