Artefact reduction on CT images of fossils to allow 3D visualisation

The evaluation of non-medical subjects with computed tomography (CT) is wid espread and has been applied to the study of fossils. This is particularly useful when fossils are encased in host rock, the removal of which would pr event a more detailed analysis of the post-death history of the specimen. C T images can be segmented and rendered to give 3D visualisation. However, C T artefact can seriously reduce the quality of such images. The artefact of most concern occurs when high attenuation materials are fou nd in lower attenuation material, but particularly when materials have irre gular shape. The artefact reduction method used involved encasing the speci men, to form a cylindrical shape using gelatine based phantom material of s imilar attenuation. The calculated effective photon energy of the CT scanne r was used, with the 'mixture rule', to iteratively determine the compositi on of the phantom material. High Z filters were used to get the required at tenuation associated with rocks. Artefact reduction was demonstrated by thi s method. (C) 2001 Elsevier Science Ltd. All rights reserved.