X-ray computer tomography (CT) is fast becoming an accepted tool within the materials science community for the acquisition of 3D images. Here the authors review the current state of the art as CT transforms from a qualitative diagnostic tool to a quantitative one. Our review considers first the image acquisition process, including the use of iterative reconstruction strategies suited to specific segmentation tasks and emerging methods that provide more insight (e.g. fast and high resolution imaging, crystallite (grain) imaging) than conventional attenuation based tomography. Methods and shortcomings of CT are examined for the quantification of 3D volumetric data to extract key topological parameters such as phase fractions, phase contiguity, and damage levels as well as density variations. As a non-destructive technique, CT is an ideal means of following structural development over time via time lapse sequences of 3D images (sometimes called 3D movies or 4D imaging). This includes information nee...

https://www.tandfonline.com/doi/pdf/10.1179/1743280413Y.0000000023

Quantitative X-ray tomography

For photon energies encountered in diagnostic radiology the shape of the scattering distributions for low-atomic-number media exhibits peaks in intensity close to the forward direction that are not predicted by conventional theoretical models. The positions and shapes of the peaks depend upon the interatomic and intermolecular configurations of the scatterers. The phenomenon is of particular interest because of its relevance to the understanding and modelling of X-ray imaging processes and the possibility that the peaking may be characteristic of tissue type. In the present study, peaks in the forward scattering distributions have been demonstrate for 19 samples of breast tissue and three tissue substitute materials using a position-sensitive photon detector and a 60 kVp X-ray source. Prominent features were observed for all samples investigated. Large differences were found in the shapes of the distributions between adipose and fibroglandular tissues and only small differences were found between carcinomas and fibroglandular tissues.

https://iopscience.iop.org/article/10.1088/0031-9155/36/1/002/pdf

Measurement of small-angle photon scattering for some breast tissues and tissue substitute materials

Coherent X-ray scatter imaging and its applications in biomedical science and industry

We use coded aperture x-ray scatter imaging to interrogate scattering targets with a pencil beam Observations from a single x-ray exposure of a flat-panel scintillation detector are used to simultaneously determine the along-beam positions and momentum transfer profiles of two crystalline powders (NaCl and Al) The system operates with a 3 cm range resolution and a momentum transfer resolution of 01 nm−1 These results demonstrate that a single snapshot can be used to estimate scattering properties along an x-ray beam, and serve as a foundation for volumetric imaging of scattering objects

Pencil beam coded aperture x-ray scatter imaging

An x-ray diffraction-based scanning method and system are described. The method includes screening for a particular substance in a container at a transportation center using a flat panel detector having a photoconductor x-ray conversion layer to detect x-rays diffracted by a particular substance in the container. The diffracted x-rays may be characterized in different ways, for examples, by wavelength dispersive diffraction and energy dispersive diffraction.

X-ray diffraction-based scanning system

A novel tomographic imaging technique is described based on the energy analysis, at fixed angle, of coherent X-ray scatter excited in an object by polychromatic radiation. The authors term their technique 'energy-dispersive X-ray diffraction tomography' (EXDT). It permits the X-ray diffraction properties of small voxels of an extended object to be measured in vivo. Tomographic information is obtained directly without the need to reconstruct from projections. EXDT images of a simple test object comprising water and various plastic materials are presented to illustrate the feasibility of the technique. Potential applications of EXDT in bone imaging are discussed.

https://iopscience.iop.org/article/10.1088/0031-9155/35/1/004/pdf

J Kosanetzky

Papers

Energy-dispersive X-ray diffraction tomography