Invited Paper AS-WeM9
3D Analysis using X-ray Computed Tomography

Wednesday, October 31, 2012, 10:40 am, Room 20

X-ray Computed Tomography (CT) can be performed on meter-sized objects or micrometer wide samples, and introduction of commercial x-ray tube-based instruments and dedicated synchrotron systems has produced an explosion of studies spanning the sciences and engineering disciplines. Using one of several numerical reconstruction methods, CT combines x-ray projections (radiographs) into a cross-sectional map, generally in 3D, of the x-ray absorption of the specimen. Other modalities (x-ray phase contrast, scattering, etc.) can also be used for reconstruction. The noninvasive interrogation allows the specimen to be studied multiple times during its evolution or to be returned undamaged to the museum collection.

This talk briefly introduces the fundamentals of x-ray CT and the different approaches to data acquisition and reconstruction. Most of the examples will focus on microCT, that is, reconstructions with isotropic volume elements (voxels) from 1-50 micrometers on edge. The first example is quantification of crack opening in a metal sample as a function of 3D position and applied load. In the second example, microCT data forms the basis of finite elements (FE) modeling of response of a spine of the sea urchin Diadema setosum to different applied loads. The third example illustrates local tomography, where data for high resolution reconstruction is only collected over a portion of the sample cross-section. Differences in x-ray phase contrast instead of x-ray absorption can be used as the basis for reconstruction; and the examples show how differences in polymers and soft tissues can be imaged using this approach. Intensity diffracted from the different phases within a specimen provide the basis for reconstructing the distribution of crystallographic phases; one example is SiC fibers in an Al matrix.