Advanced Applications of Computed Tomography by Combination of Different Methods

Advanced applications of materials need sophisticated measurement methods for research, process development and quality control. X-ray Computed Tomography (CT) is a very powerful method for non-destructive testing of materials. A CT-scanner generates a series of X-ray attenuation measurements, which are used to produce computed reconstructed images of an object. In the last years 3D-CT systems with matrix detectors have become more and more popular. In this paper we outline the extended possibilities of 3D Computed Tomography by using a 450 kV-macro focus x-ray source and a 225 kV micro-focus source within one CT system as well as the advantages by applying different CT-methods for the characterisation of one specimen. The possibility of using two different X-ray sources within one CT-device leads to considerable advantages at certain circumstances. If there are different materials in one specimen the application of two different energies can lead to a significant improvement of the contrast. Moreover, if bigger parts are scanned, the 450 kVsource can be used to get an overall image of the specimen and the 225 kV can be used to get a high resolution image of a detail. In the second section we discuss the limits of 3D-CT and apply an advanced CT-mode (region of interest CT) for the characterisation of flat parts and of selected details in large objects. With the ROICT-mode “zooming” is possible similar to optical microscopes and a resolution down to 1/10.000 of the part diameter can be reached. This is a much higher resolution as compared to usual 3D-CT.