Mark Ibison Liverpool University and CLRC Daresbury Laboratory Warrington, Cheshire, WA4 4AD, UK

1. Current Amplifier X-ray Beam Data Logger V to F Converter 120 80 10 Crystal X-rays Crystal 40 Ratemeter 25 35 Progress in medical Diffraction Enhanced Imaging at the UK Synchrotron Radiation Source C. J. Halla; M. Ibisonb; K. C. Cheunga; K. K. W. Siud, R. A. Lewisd; A. Huftone; S. J. Wilkinsonc; K. D. Rogersc; A. Roundc; K. Fayza, D. Laundya. J. Flahertya, B. Dobsona; M. Rowleyd; A. Cookf a CCLRC Daresbury Laboratory, UK; b Liverpool University, Liverpool, UK; c Cranfield University, Shrivenham, UK; dMonash University, Melbourne, Australia; e Christie Hospital, Manchester, UK; fUniversity of Melbourne, Australia This work is supported by EEC contract: CT-1999-50008, and the UK Medical Research Council. Grant: 62861 Introduction Diffraction Enhanced Imaging (DEI) is an x-ray phase contrast technique which shows great promise for a number of medical imaging problems. The source is a highly collimated flux of monochromatic x-rays, currently only available as synchrotron radiation. Phase shifts occurring as the wave passes through the object are made visible using Bragg diffraction from a post-sample analyser optic. In early 2004 the DEI system on the bending-magnet beam line 7.6 of the Daresbury SRS was used for the first time to image small medical specimens. The performance of the system and the results of these initial studies are presented. A new DEI instrument is currently in the design phase. This will be integrated on SRS wiggler station 9.4 allowing shorter x-ray wavelengths and greater flux. Progress on the design and implementation of this system is reported. DEI Alignment DEI Camera at SRS DEI Applications - Results Arthritis Study of Mouse Feet A DEI study of the feet of a susceptible strain of mouse aimed to investigate evidence for articular cartilage damage (osteoarthritis), particularly in the toe joints.. Two excised feet, one normal, the other with advanced arthritis, were compared. Swelling characteristic of the condition is clearly visible. Damage to the cartilage of the joints is less obvious, but may be discerned in the refraction images. Axial View Sagittal View For DEI, a high precision x-ray diffraction optical arrangement is required. The SRS camera design consists of a double-crystal monochromator and a double-crystalanalyser. Si311 crystal planes are used to give a sharper x-ray extinction function (‘rocking-curve’) for better contrast and higherresolution images. A small laser on a micrometer mount is used for initial alignment of the x-ray optics. It is also useful for the calibration of crystal motor drives in steps/degree. 5mm normal diseased Absorption images DEI System Schematic Use of p.i.n. Diode as Alignment Detector Refraction images Design for New DEI System (Summer 2005) Package: 8mm dia x 4mm depth Active area: 3.5mm x 3.5mm Framework and Motors for Crystal Mounting, SRS Station 9.4 Identical Monochromator and Analyser Crystals are secured to the motor shafts Monochromator - removes unwanted dispersion and provides single energy beam. Analyser - filters refraction from absorption. 500mm Window: 10mm Al foil (opaque to visible light) Intrinsic efficiency: ~ 50% (14keV) Channel-cut Crystal (with water cooling on 1st crystal taking ‘white’ X-ray beam) • Design Improvements: •  higher energy (40keV optimum), greater flux -> better penetration, lower subject dose; •  channel-cuts eliminate relative alignment of 2 crystals in a pair, so exactly parallel -> greatly reduced drift; •  greater rigidity & anti-vibration in supports, including advanced air-bearing technology; •  maximum use of existing mounts -> enable station sharing without demounting optics; •  vacuum enclosure of monochromator -> avoids convection currents and ozone damage; •  cooling provided on 1st (monochromator) crystal (see diagram) DEI exploits the refractive nature of x-rays to identify the boundaries between different media even if their x-rayattenuations are very similar. The highly- collimated synchrotron light source is ideal for this work. • Possible Future Applications: • Medical/Biological • - mammography; cartilage; osteoporosis; sport/veterinary • Materials and NDT • - voids/bubbles in low-density samples • Chemistry: Reaction Studies • - crystal formation in products, solid phase Mark Ibison Liverpool University and CLRC Daresbury Laboratory Warrington, Cheshire, WA4 4AD, UK Email: m.ibison@dl.ac.uk Tel: +44 (0)1925 603508