Referenceless beam hardening correction in 3D computed tomography images of multi-material objects
Presentation held at 17th World Conference on Nondestructive Testing, WCNDT. 25-28 October 2008, Shanghai, China
We propose a new method to reduce the effects of non-linearities such as beam hardening in Computed Tomography (CT) images. Due to the polychromatic characteristics of X-ray sources the ratio of attenuated and incoming intensity is not exactly exponential with the material thickness. Within CT images this leads to artifacts like cupping, streaks and blurring. Especially in multi-material objects with highly different attenuation characteristics these effects are even more complex. The method described in this paper allows the correction of beam hardening artifacts in multimaterial objects. The presented approach does not require any estimate or knowledge of the incident X-ray spectrum nor of material characteristics like mass density or absorption coefficients. The method uses the original projection images and works without any reference measurements. Several specimens of miscellaneous material combinations were measured with CT. Afterwards, the artifact correction was applied to show the efficiency of the proposed method.