title: Processing of projections containing phase contrast in laboratory micro-computerized tomography imaging.
abstract: Free-space-propagation-based imaging belongs to several techniques for achieving phase contrast in the hard X-ray range. The basic precondition is to use an X-ray beam with a high degree of coherence. Although the best sources of coherent X-rays are synchrotrons, spatially coherent X-rays emitted from a sufficiently small spot of laboratory microfocus or sub-microfocus sources allow the transfer of some of the modern imaging techniques from synchrotrons to laboratories. Spatially coherent X-rays traverse a sample leading to a phase shift. Beam deflection induced by the local change of refractive index may be expressed as a dark-bright contrast on the edges of the object in an X-ray projection. This phenomenon of edge enhancement leads to an increase in spatial resolution of X-ray projections but may also lead to unpleasant artefacts in computerized tomography unless phase and absorption contributions are separated. The possibilities of processing X-ray images of lightweight objects containing phase contrast using phase-retrieval methods in laboratory conditions are tested and the results obtained are presented. For this purpose, simulated and recorded X-ray projections taken from a laboratory imaging system with a microfocus X-ray source and a high-resolution CCD camera were processed and a qualitative comparison of results was made.
authors.affiliation: Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, SK-841 04 Bratislava, Slovakia.
authors.forename: Zdenko
authors.initials: Z
authors.lastname: Zápražný
authors.forename: Dušan
authors.initials: D
authors.lastname: Korytár
authors.forename: Petr
authors.initials: P
authors.lastname: Mikulík
authors.forename: Vladimír
authors.initials: V
authors.lastname: Ač
keywords: X-ray imaging; X-ray radiography; computed radiography; computerized tomography; digital radiography; phase-contrast imaging
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