Browsing by Author "Godber, S. X."

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    Classification of fracture and non-fracture groups by analysis of coherent X-ray scatter
    (Nature Publishing Group, 2016-07-01) Dicken, A. J.; Evans, J. Paul O.; Rogers, Keith; Stone, N.; Greenwood, Charlene; Godber, S. X.; Clement, J. G.; Lyburn, Iain Douglas; Martin, R. M.; Zioupos, Peter
    Osteoporotic fractures present a significant social and economic burden, which is set to rise commensurately with the aging population. Greater understanding of the physicochemical differences between osteoporotic and normal conditions will facilitate the development of diagnostic technologies with increased performance and treatments with increased efficacy. Using coherent X-ray scattering we have evaluated a population of 108 ex vivo human bone samples comprised of non-fracture and fracture groups. Principal component fed linear discriminant analysis was used to develop a classification model to discern each condition resulting in a sensitivity and specificity of 93% and 91%, respectively. Evaluating the coherent X-ray scatter differences from each condition supports the hypothesis that a causal physicochemical change has occurred in the fracture group. This work is a critical step along the path towards developing an in vivo diagnostic tool for fracture risk prediction.
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    Combined X-ray diffraction and absorption tomography using a conical shell beam
    (2019-07-15) Shevchuk, Alex; Evans, J. Paul O.; Dicken, A. J.; Elarnaut, D.; Downes, D.; Godber, S. X.; Rogers, Keith D.
    We combine diffraction and absorption tomography by raster scanning samples through a hollow cone of pseudo monochromatic X-rays with a mean energy of 58.4 keV. A single image intensifier takes 90x90 (x,y) snapshots during the scan. We demonstrate a proof-of-principle of our technique using a heterogeneous three-dimensional (x,y,z) phantom (90x90x170 mm3) comprised of different material phases, i.e., copper and sodium chlorate. Each snapshot enables the simultaneous measurement of absorption contrast and diffracted flux. The axial resolution was ~1 mm along the (x,y) orthogonal scan directions and ~7 mm along the z-axis. The tomosynthesis of diffracted flux measurements enable the calculation of d-spacing values with ~0.1 Å full width at half maximum (FWHM) at ~2 Å. Thus the identified materials may be color-coded in the absorption optical sections. Characterization of specific material phases is of particular interest in security screening for the identification of narcotics and a wide range of homemade explosives concealed within complex “everyday objects.” Other potential application areas include process control and biological imaging.
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    Depth resolved snapshot energy-dispersive X-ray diffraction using a conical shell beam
    (Optical Society of America, 2017-08-23) Dicken, A. J.; Evans, J. Paul O.; Rogers, Keith; Prokopiou, Danae; Godber, S. X.; Wilson, M.
    We demonstrate a novel imaging architecture to collect range encoded diffraction patterns from overlapping samples in a single conical shell projection. The patterns were measured in the dark area encompassed by the beam via a centrally positioned aperture optically coupled to a pixelated energy-resolving detector. We show that a single exposure measurement of 0.3 mAs enables d-spacing values to be calculated. The axial positions of the samples were not required and the resultant measurements were robust in the presence of crystallographic textures. Our results demonstrate rapid volumetric materials characterization and the potential for a direct imaging method, which is of great relevance to applications in medicine, non-destructive testing and security screening.
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    X-ray absorption tomography employing a conical shell beam
    (Optical Society of America, 2016-12-12) Evans, J. Paul O.; Godber, S. X.; Elarnaut, F.; Downes, D.; Dicken, A. J.; Rogers, Keith
    We demonstrate depth-resolved absorption imaging by scanning an object through a conical shell of X-rays. We measure ring shaped projections and apply tomosynthesis to extract optical sections at different axial focal plane positions. Three-dimensional objects have been imaged to validate our theoretical treatment. The novel principle of our method is scalable with respect to both scan size and X-ray energy. A driver for this work is to complement previously reported methods concerning the measurement of diffracted X-rays for structural analysis. The prospect of employing conical shell beams to combine both absorption and diffraction modalities would provide enhanced analytical utility and has many potential applications in security screening, process control and diagnostic imaging.