Mark Ibison

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

Email: m.ibison@dl.ac.uk

Tel: +44 (0)1925 603508

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.

DEI AlignmentDEI Camera at SRS DEI Applications - Results

DEI exploits the refractive nature of x-rays to identify the boundaries between different media even if their x-ray attenuations are very similar. The highly- collimated synchrotron light source is ideal for this work.

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-crystal analyser. Si311 crystal planes are used to give a sharper x-ray extinction function (‘rocking-curve’) for better contrast and higher resolution images.

Axial View Sagittal View

Absorption images

Refraction images

normal diseased

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

Channel-cut Crystal (with water cooling on 1st crystal taking ‘white’ X-ray beam)

Framework and Motors for Crystal Mounting, SRS Station 9.4

Identical Monochromator and Analyser Crystals are secured to the motor shafts

Progress in medical Diffraction Enhanced Imaging at the UK Synchrotron Radiation SourceC. 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; d Monash University, Melbourne, Australia; e Christie Hospital, Manchester, UK; f University of Melbourne, Australia

This work is supported by EEC contract: CT-1999-50008, and the UK Medical Research Council. Grant: 62861

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.

Crystal

Crystal40

10

12080

2535

X-rays

Design for New DEI System (Summer 2005)

5mm

500mm

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)

Use of p.i.n. Diode as Alignment Detector

Data Logger

V to F Converter

Ratemeter

Current Amplifier

X-ray Beam

DEI System Schematic

Monochromator - removes unwanted dispersion and provides single energy beam.

Analyser - filters refraction from absorption.

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.

Package:8mm dia x 4mm depth

Active area: 3.5mm x 3.5mm

Window: 10m Al foil (opaque to visible light)Intrinsic efficiency: ~ 50% (14keV)

Introduction