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Proceedings Paper

2D beam hardening correction for micro-CT of immersed hard tissue
Author(s): Graham Davis; David Mills
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Paper Abstract

Beam hardening artefacts arise in tomography and microtomography with polychromatic sources. Typically, specimens appear to be less dense in the center of reconstructions because as the path length through the specimen increases, so the X-ray spectrum is shifted towards higher energies due to the preferential absorption of low energy photons. Various approaches have been taken to reduce or correct for these artefacts. Pre-filtering the X-ray beam with a thin metal sheet will reduce soft energy X-rays and thus narrow the spectrum. Correction curves can be applied to the projections prior to reconstruction which transform measured attenuation with polychromatic radiation to predicted attenuation with monochromatic radiation. These correction curves can be manually selected, iteratively derived from reconstructions (this generally works where density is assumed to be constant) or derived from a priori information about the X-ray spectrum and specimen composition. For hard tissue specimens, the latter approach works well if the composition is reasonably homogeneous. In the case of an immersed or embedded specimen (e.g., tooth or bone) the relative proportions of mineral and “organic” (including medium and plastic container) species varies considerably for different ray paths and simple beam hardening correction does not give accurate results. By performing an initial reconstruction, the total path length through the container can be determined. By modelling the X-ray properties of the specimen, a 2D correction transform can then be created such that the predicted monochromatic attenuation can be derived as a function of both the measured polychromatic attenuation and the container path length.

Paper Details

Date Published: 3 October 2016
PDF: 8 pages
Proc. SPIE 9967, Developments in X-Ray Tomography X, 996707 (3 October 2016); doi: 10.1117/12.2238540
Show Author Affiliations
Graham Davis, Queen Mary Univ. of London (United Kingdom)
The London School of Medicine and Dentistry (United Kingdom)
David Mills, Queen Mary Univ. of London (United Kingdom)
The London School of Medicine and Dentistry (United Kingdom)

Published in SPIE Proceedings Vol. 9967:
Developments in X-Ray Tomography X
Stuart R. Stock; Bert Müller; Ge Wang, Editor(s)

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