Transcript Powerpoint 2.1M - University of Surrey

S
S J Doran, P Jenneson,
P McDonald, E Morton,
N Spyrou
Department of Physics,
University of Surrey,
Guildford, GU2 7XH, UK
Healthcare research in the
Physics Department
Dr S J Doran
Lecturer in Magnetic Resonance Imaging
Department of Physics
School of Electronics and Physical Sciences
Structure of talk
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Physics personnel with medical interests and
healthcare-related projects underway in Physics
Four brief case studies
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MRI of the diffusion properties of tumours
Skin imaging
Radiation dosimetry
Characterisation of distortion in MRI
Physics department “healthcare”personnel
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Prof Tony Clough
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Ion beam analysis (healthcare products)
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Dr Simon Doran
Magnetic Resonance Imaging
Radiation dosimetry
e-Health
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Soft condensed matter Physics
Skin imaging
Imaging of solvent ingress into dental resins
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Dr Paul Jenneson
Ion beam analysis
X-ray CT micro-tomography
Radiation transport (Monte Carlo simulation)
Dr Ed Morton
(on secondment to Creative X-ray Ltd.)
X-ray imaging
Novel control systems for dose-reduction
Dr Walter Gilboy
Radiation dosimetry and protection
Prof Peter McDonald
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Prof Nicholas Spyrou
Positron Emission Tomography
Nuclear Medicine
Epigastrography
Trace element detection in medical
conditions (e.g., Alzheimer’s)
Ion beam analysis
… and many more!
MRI measurements of diffusion: (1) Cancer
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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 wellestablished 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)
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We developed novel MRI
methodology to allow diffusion
coefficients to be measured as part
of a rectal tumour study.
The diffusion coefficient measured
before treatment was correlated
with the tumour response.
Diffusion coefficient / cm2 s-1
MRI measurements of diffusion: (1) Cancer
% regression in tumour size after chemoradiation
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.
The Lancet 360, 307–308 (2002)
A Dzik-Jurasz, C Domenig, S Doran et al.
MRI measurements of diffusion: (2) Skin
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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
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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.
Intensity (a.u.)
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Result after
application of
cream for 5 mins.
10
8
6
4
2
0
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250 500 750 1000
“Dry” skin
before cream
applied (normal)
Position (microns)
P Glover, B Newling, P McDonald (UniS)
M Dias, J Hadgraft (University of Cardiff)
Measurement of radiation dose in 3D
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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.
Target
organ
Organs
to spare
Schematic prostate treatment
Until recently, this has not been
possible.
Phys. Med. Biol. 43, 1113-1132 (1998)
M Oldham et al.
Treatment plan
MRI-derived dose map
Measurement of radiation dose in 3D
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However, these can be extremely
slow (~ 6 hours for a 3-D scan).
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.
-1
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Methods based on MRI have
previously been used to measure
the dose distribution in 3D.
Change in
optical absorbance / cm
/ cm-1
absorbance)
D(optical
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0.4
FXG spectral
dose-response
0.2
0.0
-0.2
350
400
450
500
550
600
Wavelength / nm
Phys. Med. Biol. (2001) S Doran, K Kleinkoerkamp,
P Jenneson, E Morton, W Gilboy
Wavelength / nm
650
700
Measurement of radiation dose in 3D
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Turntable controlled by
acquisition computer via
stepper motors
We have developed a new method of
scanning the gels — 3-D optical
computed tomography (OCT).
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OCT is potentially two orders of
magnitude cheaper than its MRI rival.
Diffuser screen on
which real shadow
image forms
Exposed gel
Lens  parallel beam
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Unexposed gel
Hg
lamp
Scanning tank
with matching
medium
Cylindrical lens,
pinhole and filter 
pseudo point-source
CCD
detector
Standard 50mm
camera lens
PC with framegrabber card
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
10 Gy
57 mm
0 Gy
Distortion in Magnetic Resonance Images
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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?
S Doran (UniS), L Moore, S Reinsberg, M Leach (Institute of Cancer Research)
Distortion in Magnetic Resonance Images
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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.
By analysing around 40,000
point-to-point correspondences
between CT and MR images, we
obtain 3-D distortion maps.
x-distortion / mm
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10
-10
100
200
y / mm
-100 -200
x / mm
S Doran (UniS), L Moore, S Reinsberg, M Leach (Institute of Cancer Research)
Distortion in Magnetic Resonance Images
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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 radiation
Less patient discomfort / inconvenience
Saves NHS money
S Doran (UniS), L Moore, S Reinsberg, M Leach (Institute of Cancer Research)