Medical- and Radiation Physics Research at Surrey

Transcription

1 Medical- and Radiation Physics Research at Surrey D.A. Bradley Department of Physics Centre for Nuclear and Radiation Physics University of Surrey Guildford United Kingdom * d.a.bradley@surrey.ac.uk

2 Topic Areas 1. Extracellular matrix, disease processes and therapeutic interventions; microvascularity modelling 2. Development of active and passive detectors and dosimeters 3. Radioactivity in the Oil and Gas industry 4. Security scanning

3 Synovial Joints Tide mark Subchondral bone Cartilage (~0.65mm) superficial layer of cartilage

4 Major mass comprises ECM and polyelectrolytes in solution

5 Cartilage: a structured system of cartilage with lipid surface Schematic representation of a typical articular cartilage membrane showing the phospholipids lamellar structure (Pawlak and Oloyede, 2007).

6 A section from the equine metacarpophalangeal joint and human femoral head cartilage lesion subchondral bone

7 XRF profile; X-ray system + Khumakhov lens Articular Cartilage Zn Sr Subchondral Bone Ca 500 μm Cartilage-Calcified Cartilage interface

8 Sulphate (SO4--) Presence/loss of chondroitin sulphate in cartilage

9 P Ca S K Cl S Na Na

10 Lubricin and Chloride (Cl ) at the phospholipid surface

11 SAXS at PSI

12 csaxs Mappings

13 Further layers in images of different length scales

14 In the bone Centre of cartilage Inner part of cartilage Outer part of cartilage

15 Breast Tissue Biopsy, 10 µm thin sections

16 PIXE/PIGE and RBS Analysis Shielding large volume HPGe detector for PIGE

17 PIXE and PIGE

18 PIGE 3 MeV proton beam ~ 100 µm x 6 µm spot size, beam current ~ 0.5 µa 19 F(p,p'γ ) 19 F; γ-rays of 110 and 197 kev 23 Na(p,p'γ) 23 Na & 23 Na(p,α'γ) 20 Ne; γ-rays: 440, 1634, 1636 kev 35 Cl(p,p'γ) 35 Cl and 37 Cl(p,γ) 38 Ar; γ-rays of 1220 and 1640 kev

19 Phase propagation provides for edgeenhanced x-ray imaging:

20 Effects of Ionizing Radiation on ECM

21 stress (MPa) yrs 12 yrs 17 yrs 23 yrs

22 Modelling tumour oxygenation

23 Dosimeter Development Ge-Doped Silica Optical Fibres (CorActive High-Tech, Canada) PRESAGE Radiochromic Plastic (Heuris Pharma, LLC, US) 9.7 mm 125 μm 22 mm 18 mm

24 Characterisation of Fibres

25 Purpose-Built Optical CT Microscope Image from Doran et al., Phys. Med. Biol (2010)

26 MTF and Spatial Resolution (c) A B C D 80 E MTF (%) 60 F G H I J K 40 L M N Spatial Frequency (lp/mm) The line spacing in lp/mm as follows: (A) 1.37, (B) 2.04, (C) 2.73, (D) 3.43, (E) 0.68, (F) 4.10, (G) 5.43, (H) 27.8, (I) 35.7, (J) 10.2, (K) 13.5, (L) 5.43, (M) 20.8, (N) 6.85;

27 Peak-Valley Dose Ratio of MRT Atypical3 3mm 2 array of parallel microbeams of nominal FWHM 50 μm and c.t.c. 400 μm projected onto a centred 9.7 mm diameter PRESAGETM cylinder, with entry dose 600 Gy; (a) Projection image Sample 3 (nominal FWHM 50 μm, 400 μm c-t-c); (b) profile through the dotted line in (a).

28 Wide band gap semiconductor materials for room temperature radiation detector application Page 28 Application areas High energy and nuclear physics Neutron detection & monitoring in nuclear industry High energy X and γ ray detection for medical and security applications Photon science/synchrotron instrumentation Medical dosimetry High fluence backgrounds and harsh environments... Commercially available PTW chambers based on natural diamonds

29 Two main groups of materials studied High Z material for X/ spectroscopy and imaging Radiation hardness/tissue equivalent Neutron detection, TOF Cd x Zn 1-x Te 3 mm Birefringence pattern diamond HgI 2 & TlBr curic_iodide_detectors.htm CdTe, CdZnTe, HgI 2, TlBr 3 mm Diamond, SiC, polymers Also, increasing activity in TOF PET with SiPM SiPM coupled to fast Scintillators for timing of -signals Page 29

30 What we are interested in Understanding and optimizing detector performance in terms of - energy resolution - timing - long term stability - temperature stability study charge transport in the bulk (resistivity, charge carrier mobility, life time, trapping effects correlate to optical measurements of defect distributions Study charge transport across semiconductor/metal interfaces Optimise device geometry (i.e. electrode geometry) and signal processing (digital pulse processing) Prototype detector testing Page 30

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32 Preliminary results on breast tissue characterisation using X-ray diffraction CT A single point detector was used for this proof-of-principle A pixellated detector would allow acquisition times of a few minutes Possibility of use in operating theatre or pathology lab XRD allows cancer detection and staging Conventional X-ray imaging would not allow discrimination of cancer from fibroglandular tissue and benign tumour

33 Iodine K-edge subtraction imaging The two images needed for KES are acquired in one shot by integrating different bands in the spectrum transmitted behind the sample Less dose No motion artifacts Currently working on iodine for breast imaging application Seeking alternative contrast agents! LOW Test object with 1, 2 and 3 mm Ø tubes filled with iodine contrast agent Dose 1/20 of conventional dose HIGH DIFF

34 Forms of NORM found in Oil and Gas Production Facilities Source: Guidelines for Naturally Occurring Radioactive Materials, Australian Petroleum Production & Exploration Association Limited, 2002

35 NORM Accumulation in Oil Fields Source: Guidelines for the management of naturally occurring radioactive materials (NORM) in the oil and gas industry, International Association of Oil and Gas Producers, Report No. 412, 2008.

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37 NORM in North African Oil Fields NORM identified in Libya in1998 [1] external exposure ranged from 22 μsv/h to 335 μsv/h [1]. Few studies have been made for land-based oil production facilities.

38 DOI: doi: /j.apradiso

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40 We invite collaboration Acknowledgements