Metal Artifacts in Attenuation and Phase Contrast X-Ray Microcomputed Tomography: A Comparative Study

Experimental Mechanics - Metal artifacts arising around high-density components are a widely known problem in X-ray computed tomography (XCT) for both medical and industrial applications. Although...     

Applications of X-ray synchrotron microtomography for non-destructive 3D studies of paleontological specimens

Paleontologists are quite recent newcomers among the users of X-ray synchrotron imaging techniques at the European Synchrotron Radiation Facility (ESRF). Studies of the external morphological characteristics of a fossil organism are not sufficient to extract all the information for a paleontological study. Nowadays observations of internal structures become increasingly important, but these observations should be non-destructive in order to preserve the important specimens. Conventional microtomography allows performing part of these investigations. Nevertheless, the best microtomographic images are obtained using third-generation synchrotrons producing hard X-rays, such as the ESRF. Firstly, monochromatisation avoids beam hardening that is frequently strong for paleontological samples. Secondly, the high beam intensity available at synchrotron radiation sources allows rapid data acquisition at very high spatial resolutions, resulting in precise mapping of the internal structures of the sample. Thirdly, high coherence leads to additional imaging possibilities: phase contrast radiography, phase contrast microtomography and holotomography. These methods greatly improve the image contrast and therefore allow studying fossils that cannot be investigated by conventional microtomography due to a high degree of mineralisation or low absorption contrast. Thanks to these different properties and imaging techniques, a synchrotron radiation source and the ESRF in particular appears as an almost ideal investigation tool for paleontology. PACS 01.30.Cc; 07.05.Hd; 68.37.Yz; 29.20.Lq; 81.70.Tx     

Fresnel-propagated submicrometer x-ray imaging of water-immersed tooth dentin

Structural investigations of materials in diverse fields such as biomimetics, materials engineering, and medicine have much to benefit from 3D nondestructive microscopy of representative samples of wet tissues. Phase contrast appearing in tomograms produced by Fresnel propagation of partially coherent x-ray fields is useful for visualizing submicrometer features within water-immersed samples. However, spurious contributions such as those due to randomly appearing bubbles lead to distorted images. By improving the statistics during image acquisition and reconstruction, submicrometer-sized tubules in human tooth dentin are observed. This type of wet imaging is directly applicable to the study of many mineralized tissues.