Browsing by Author "Wilson, M."

Now showing 1 - 3 of 3
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    Confocal energy-dispersive X-ray diffraction tomography employing a conical shell beam
    (Optical Society of America, 2019-07-01) Dicken, Anthony; Evans, J. Paul O.; Rogers, Keith; Prokopiou, Danae; Godber, Simon; Elarnaut, F.; Shevchuk, Alex; Downes, D.; Wilson, M.
    We introduce a new high-energy X-ray diffraction tomography technique for volumetric materials characterization. In this method, a conical shell beam is raster scanned through the samples. A central aperture optically couples the diffracted flux from the samples onto a pixelated energy-resolving detector. Snapshot measurements taken during the scan enable the construction of depth-resolved dark-field section images. The calculation of dspacing values enables the mapping of material phase in a volumetric image. We demonstrate our technique using five ~15 mm thick, axially separated samples placed within a polymer tray of the type used routinely in airport security stations. Our method has broad analytical utility due to scalability in both scan size and X-ray energy. Additional application areas include medical diagnostics, materials science, and process control
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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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    Developing focal construct technology for in vivo diagnosis of osteoporosis
    (IOP, 2019-03-18) Greenwood, Charlene; Rogers, Keith; Wilson, M.; Lyburn, Iain Douglas; Evans, P.; Prokopiou, Danae
    Osteoporosis is a prevalent bone disease around the world, characterised by low bone mineral density and increased fracture risk. Currently, the gold standard for identifying osteoporosis and increased fracture risk is through quantification of bone mineral density (BMD), using dual energy X-ray absorption (DEXA). However, the use of BMD to diagnose osteoporosis is not without limitation and arguably the risk of osteoporotic fracture should be determined collectively by bone mass, architecture and physicochemistry of the mineral composite building blocks. Rather than depending exclusively on the 'mass' of bone, our previous research investigated predicting the risk of fracture using 'bone quality'. The work highlighted that the material properties of OP tissue differ significantly to that of 'normal' bone and for the first time reported the clinical value of new biomarkers (obtained from X-ray scatter signatures) for fracture risk prediction. Thus, in order to improve fracture prediction models, diagnostic tools need to be developed which not only measure bone mineral density, but also bone quality. This pilot study builds on our previous work and aims to develop a new technology, Focal Construct Technology (FCT), which is hoped can measure XRD signatures in vivo. Our previous work was performed entirely with interrogating probes applied in transmission mode. This has some disadvantages that would be overcome were reflection mode employed. This study involves the creation of unique, high impact data with the potential to form the basis of a new generation of medical diagnostic instrumentation. A systematic series of conventional reflection mode ex vivo experiments were performed in which bone specimens were examined through increasing thicknesses of overlaying muscle/fat/skin. Further, we applied FCT to these geometries. This had not previously been attempted and required some initial modelling to ensure correct topologies of the hollow beams. The results from this study suggest it may be possible to obtain the parameters in vivo with the same precision as those obtained within the laboratory when using FCT.