Healthcare research in the Physics Department

Dr S J Doran Lecturer in Magnetic Resonance Imaging

Department of PhysicsSchool of Electronics and Physical Sciences

S Department of Physics,University of Surrey,Guildford, GU2 7XH, UK

S J Doran, P Jenneson, P McDonald, E Morton, N Spyrou

Structure of talk

• Physics personnel with medical interests andhealthcare-related projects underway in Physics

• Four brief case studies

MRI of the diffusion properties of tumours

Skin imaging

Radiation dosimetry

Characterisation of distortion in MRI

Physics department “healthcare”personnel

• Prof Tony CloughIon beam analysis (healthcare products)

• Dr Simon DoranMagnetic Resonance ImagingRadiation dosimetrye-Health

• Dr Walter GilboyRadiation dosimetry and protection

• Dr Paul Jenneson Ion beam analysisX-ray CT micro-tomographyRadiation transport (Monte Carlo simulation)

• Prof Peter McDonald Soft condensed matter PhysicsSkin imagingImaging of solvent ingress into dental resins

• Dr Ed Morton (on secondment to Creative X-ray Ltd.) X-ray imagingNovel control systems for dose-reduction

• Prof Nicholas SpyrouPositron Emission TomographyNuclear MedicineEpigastrographyTrace element detection in medicalconditions (e.g., Alzheimer’s)Ion beam analysis

… and many more!

MRI measurements of diffusion: (1) Cancer

• Magnetic Resonance Imaging can be used to measure the speed of diffusion of water molecules.

• The technique is widely applied in brain imaging, as there is a well-established link between altered diffusion values and stroke.

• Extra-cranially, the technique has obvious potential, but this has been difficult to realise for a number of technical reasons.

Lancet 360, 307–308 (2002)

MRI measurements of diffusion: (1) Cancer

• We developed novel MRI methodology to allow diffusion coefficients to be measured as part of a rectal tumour study.

The Lancet 360, 307–308 (2002) A Dzik-Jurasz, C Domenig, S Doran et al.

• Data acquisition is at the limit of what is technically possible with the current generation of scanners

• With improved methodology, this could become a prognostic test.

% regression in tumour size after chemoradiation

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• The diffusion coefficient measured before treatment was correlated with the tumour response.

MRI measurements of diffusion: (2) Skin

• Most Magnetic Resonance Imaging scanners are based round a magnet with a cylindrical geometry.

• This is good for whole-body scans, but not for scanning thin samples.

• Dr Glover and Prof McDonald put forward a novel magnet design, called GARField (Gradient At Right- Angles to Field).

• Resolution of the new scanner is now of the order of tens of microns, rather than the few mm of a routine clinical scan.

J Magn. Reson. 139, 90 P Glover, P Aptaker, J Bowler, E Ciampi, P McDonald

MRI measurements of diffusion: (2) Skin

• This type of imaging is very different from the sort of MR “pictures” we are used to seeing.

• We can measure quantitatively the diffusion of compounds through the skin and follow them with time.

P Glover, B Newling, P McDonald (UniS) M Dias, J Hadgraft (University of Cardiff)

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“Dry” skin before creamapplied (normal)

Result after application of cream for 5 mins.

Measurement of radiation dose in 3D

• Modern radiotherapy treatments can be extremely complicated, in order to try and spare healthy tissue whilst killing the cancer.

• Such treatments require extremely high spatial accuracy of delivery.

• Hence, there is a pressing need to be able to measure the dose delivered.

• Until recently, this has not been possible.

Organs to spare

Target organ

Schematic prostate treatment

Treatment plan MRI-derived dose mapPhys. Med. Biol. 43, 1113-1132 (1998) M Oldham et al.

Measurement of radiation dose in 3D

• Methods based on MRI have previously been used to measure the dose distribution in 3D.

• However, these can be extremely slow (~ 6 hours for a 3-D scan).

Phys. Med. Biol. (2001) S Doran, K Kleinkoerkamp, P Jenneson, E Morton, W Gilboy Wavelength / nm

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FXG spectraldose-response

• For a number of years, we have been investigating a novel method based on a gel that changes colour when irradiated from orange to purple.

Measurement of radiation dose in 3D

• We have developed a new method of scanning the gels — 3-D opticalcomputed tomography (OCT).

Hglamp

Cylindrical lens, pinhole and filter pseudo point-source

Lens parallel beam

Scanning tank with matching medium

Exposed gel

Unexposed gel Diffuser screen on which real shadow image forms

CCDdetector

Standard 50mmcamera lens

PC with frame-grabber card

Turntable controlled by acquisition computer via stepper motors

0 Gy

10 Gy57 mm

• OCT is potentially two orders of magnitude cheaper than its MRI rival.

• OCT is potentially two orders of magnitude faster than MRI.

• Applications include brachytherapy, conformal radiotherapy and IMRT, radiation protection/ accident prevention.

Phys. Med. Biol. (2001) S Doran, K Kleinkoerkamp, P Jenneson, E Morton, W Gilboy

Distortion in Magnetic Resonance Images

S Doran (UniS), L Moore, S Reinsberg, M Leach (Institute of Cancer Research)

• What would you say if you knew that MRI scans could turn this …

… into this?

• Would you rely on MRI data to plan your surgery or radiotherapy?

Distortion in Magnetic Resonance Images

S Doran (UniS), L Moore, S Reinsberg, M Leach (Institute of Cancer Research)

• We are researching how to correct MR images to make them reliable enough for surgery.

• By using a specially designed test object, we can work out how each pixel of the image is displaced.

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• By analysing around 40,000 point-to-point correspondences between CT and MR images, we obtain 3-D distortion maps.

Distortion in Magnetic Resonance Images

S Doran (UniS), L Moore, S Reinsberg, M Leach (Institute of Cancer Research)

• Data from the test object is used in conjunction with patient image data in order to produce distortion corrected maps.

• The eventual aim is to make it possible to eliminate the necessity for CT scans in the planning of some radiotherapy treatments.

No radiationLess patient discomfort /

inconvenienceSaves NHS money