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Diffraction Enhanced Imaging at the UK Synchrotron Radiation Source

Diffraction Enhanced Imaging at the UK Synchrotron Radiation Source. M.Ibison, K.C.Cheung, K.Siu, C.J.Hall, R.A.Lewis, A. Hufton, S.J.Wilkinson, K.D.Rogers, A.Round. Principal Objectives of DEI Development Activities at the SRS.

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Diffraction Enhanced Imaging at the UK Synchrotron Radiation Source

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  1. Diffraction Enhanced Imaging at the UK Synchrotron Radiation Source M.Ibison, K.C.Cheung, K.Siu, C.J.Hall, R.A.Lewis, A. Hufton, S.J.Wilkinson, K.D.Rogers, A.Round

  2. Principal Objectives of DEI Development Activities at the SRS • reduce the proportion of available time spent on alignment, in preparation for useful imaging • increase reliability and stability in mechanics and software, to improve image quality • approach a ‘turn-key’ facility for DEI users without need for expertise in the detailed method. • Also:- • obtain useful experience for designing 2nd generation DEI on higher-energy SRS station.

  3. DEI System – Station 7.6 • High precision optics required • 2-crystal monochromator and 2-crystalanalyser • Si 311 crystals give sharper x-ray extinction • Higher contrast, higherresolution images.

  4. X-Ray Optics AlignmentLaser • red beam (l = 623nm), <1 mW output • compact (2.5cm x 1cm), power source = 2 x 1.5V batteries • micrometer adjustments, Vertical & Horizontal angle & displacement • spot of 2mm x 1mm at working range of 2m

  5. Monochromator and 4-Crystal Alignment using Laser Assistance Monochromator Alignment Analyser Alignment NOTE: Vertical Spacing between crystals exaggerated for clarity.

  6. Laser Method for Determination of Motor Drive Calibration Factors

  7. Laser Method for Determination of Motor Drive Calibration Factors

  8. Ionisation Chamber for X-Ray Beam Location • polymer window (5cm x 1cm) • thickness = 70mm • atmospheric pressure

  9. Silicon p.i.n. PhotoDiodefor DEI Alignment • Sensitive Area: 3.5mm x 3.5mm • Thickness (effective): 250mm • Window: 10mm Al foil (for 14keV X-rays)

  10. Medical Applications of DEI: Mouse Feet Study Normal Diseased Normal Diseased Refraction Images Absorption Images • vertical view • through sole of foot

  11. Mouse Feet Study (2) Refraction Images Normal   Diseased Normal   Diseased • horizontal view • through side of foot Absorption Images

  12. DEI Insect Studies Beetle Earwig Refraction Image Absorption Image

  13. Computerised Tomography – Principles

  14. Examples of CT Reconstruction Input to Reconstruction = Set of Projections (Sinogram) Results of Reconstruction = Cross-Section (Slice)

  15. Effect of Filtering on Reconstructed Image Unfiltered Filtered

  16. Volume Visualisation • 3-D Rendering of a Mouse Liver, based on CT dataset (ELETTRA) • Uses Volume/Surface modelling features of software packages

  17. Second-Generation DEI System:Some Design Considerations • higher energy and greater flux (on wiggler Station) - better penetration, lower subject dose • channel-cut crystals - facilitate alignment, reduce drift • rigidity and anti-vibration built into support structure • mountings optimize use of existing framework - station sharing remains feasible • vacuum enclosure of the monochromator - avoids convection currents and ozone damage risk • cooling provision for the 1st crystal - highest heat loading from ‘white’ beam.

  18. Acknowledgements The authors would like to thank:- Medical Research Council - for funding this research programme Giuseppe Salvini and Janet Groves (CLRC Daresbury) - design and construction of the p.i.n. diode device Greg Johnson (CLRC Rutherford Appleton Laboratory) - design and implementation of DSP reconstruction system Andrew Mather (Liverpool University) - Java implementation of the FBP reconstruction software.

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