Advanced X-ray computed tomography methods: High resolution CT, quantitative CT, 4DCT and phase contrast CT

During the last years, a number of novel X-ray imaging and data processing methods have been developed. This work gives an overview of some recent CT-developments: 1) High resolution CT: State of the art laboratory CT-systems are able to reach resolutions down to 0.7 μm (or even lower) and voxels sizes down to 50 nm. Several applications of high-resolution CT are presented and discussed. 2) Quantitative CT: In the beginning of industrial CT mainly images were generated for visual inspection. Nowadays software tools and methods are getting increasingly important to determine quantitative data from CT scans with reasonable accuracy. These quantitative values can be lengths, diameters, distances, fibre orientations, porosity values, parameters characterizing the 3D-microstructure, etc. 3) 4DCT or In-situ CT: Typical 4DCT and in-situ investigations include the thermo-mechanical behaviour (tension, compression, torsion at different temperatures) of materials, phase transitions, physical reactions (e.g. melting, sintering, diffusion...), chemical reactions, etc. CT is one of the most powerful methods for in-situ investigations of a material since it generates the complete 3D information without, in most of the cases, affecting the studied system. 4) Phase contrast CT: X-ray computed tomography phase imaging methods can be classified into propagation based methods, interferometric methods and other techniques. In this presentation, we compare an interferometric method based on the Talbot-Lau interferometer with propagation based phase contrast CTmethods and discuss the possibilities and restrictions. 5.) Further trends: In addition we report on further trends and methods such as XXL-CT / Robot-CT , In-line CT/High speed CT, coupling of CT with material simulation, application of new X-ray sources and detectors (e.g. photon counting detectors), application of multi-energy techniques, etc.