6th July 2009, NZIP6th July 2009, NZIP

Where’s the Physics in Where’s the Physics in Medicine?Medicine?

Richard WattsRichard WattsDirector of MR Research, Van der Veer Director of MR Research, Van der Veer

InstituteInstitute

Dept. of Physics and AstronomyDept. of Physics and Astronomy

University of CanterburyUniversity of Canterbury

6th July 2009, NZIP6th July 2009, NZIP

MRI X-Ray NuclearImaging

Therapy

DiagnosticImaging

Therapy

6th July 2009, NZIP6th July 2009, NZIP 13th March 200713th March 2007

X-Ray ImagingX-Ray ImagingContrast: Density, Atomic NumberContrast: Density, Atomic Number

X-raysource

Object

Detector

Phil and Anthony Butler, UC and MARS Bioimaging

December 22nd, 1895Wilhelm Roentgen

“Builder survives nailgun accident”

6th July 2009, NZIP6th July 2009, NZIP

PneumoencephalographyPneumoencephalography

Pneumoencephalogram from Moore et al (1935) 'Encephalographic studies in mental disease' - American Journal of Psychiatry

6th July 2009, NZIP6th July 2009, NZIP

Medipix – Spectroscopic X-ray Imaging Medipix – Spectroscopic X-ray Imaging (CERN)(CERN)

Separate Density and Atomic NumberSeparate Density and Atomic Number

“Colour X-ray Imaging”

6th July 2009, NZIP6th July 2009, NZIP

Computed Tomography (CT)Computed Tomography (CT)3D X-Ray Imaging3D X-Ray Imaging

6th July 2009, NZIP6th July 2009, NZIP

Computed Tomography (CT)Computed Tomography (CT)3D X-Ray Imaging3D X-Ray Imaging

6th July 2009, NZIP6th July 2009, NZIP

Computed Computed Tomography Tomography

(CT)(CT)3D X-Ray Imaging3D X-Ray Imaging

Prototype MARS SpectroscopicCT scanner

CT Scanner rotating

6th July 2009, NZIP6th July 2009, NZIP

Nuclear Imaging, Gamma Camera Nuclear Imaging, Gamma Camera (1957)(1957)

Contrast: Concentration of radiopharmaceuticalContrast: Concentration of radiopharmaceutical

6th July 2009, NZIP6th July 2009, NZIP

Radiopharmaceuticals for Nuclear Radiopharmaceuticals for Nuclear ImagingImaging

ParentParent DecaDecay y

ModeMode

Half-Half-lifelife

DaughterDaughter Decay Decay ModeMode

Half-Half-lifelife

Decay Decay ProductProduct

6969GeGe

GermaniumGermaniumECEC 271 271

daysdays

6868GaGa

GalliumGalliumββ++, EC, EC 68 min68 min 6868ZnZn

ZincZinc8181RbRb

RubidiumRubidiumββ++, , ECEC

4.5 hr4.5 hr 81m81mKrKr

KryptonKryptonITIT 13.5 s13.5 s 8181KrKr

KryptonKrypton8282StSt

StrontiumStrontiumECEC 25.5 25.5

daysdays

8282RbRb

RubidiumRubidiumββ++ 75 s75 s 8282KrKr

KryptonKrypton9999MoMo

MolybdenuMolybdenumm

ββ-- 67 hr67 hr 99m99mTcTc

TechnetiuTechnetiumm

ITIT 6 hr6 hr 9999TcTc

EC = Electron capture, IT = Isometric transition

6th July 2009, NZIP6th July 2009, NZIP

Single Photon Emission Computed Tomography, SPECTSPECT

3D Nuclear Imaging3D Nuclear Imaging

Bushberg, Essential Physics of Medical Imaging

6th July 2009, NZIP6th July 2009, NZIP

Positron Emission Tomography Positron Emission Tomography (PET)(PET)

18F-FDG, T1/2 ~ 2 hours

6th July 2009, NZIP6th July 2009, NZIP

Magnetic Resonance Imaging, Magnetic Resonance Imaging, (n)MRI(n)MRI

Hydrogen Hydrogen NNuclei are uclei are aligned by a big aligned by a big MMagnetic agnetic FieldField

RResonant frequency given esonant frequency given by Larmor equationby Larmor equation

Nuclei absorb Nuclei absorb radiofrequency energy at radiofrequency energy at that frequency and then that frequency and then re-emit energyre-emit energy

Magnetic field gradient Magnetic field gradient coils allow the field (and coils allow the field (and resonant frequency) to resonant frequency) to vary with location in x,y,z – vary with location in x,y,z – IImagingmaging

“You know, what these people do is really clever. They put little spies into molecules and send radio signals to them, and then they have to radio back what they are seeing.”

Niels Bohr

B

6th July 2009, NZIP6th July 2009, NZIP

Guess who?Guess who?

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Structural Brain Imaging with Structural Brain Imaging with MRIMRI

T1 T2 T2 FLAIR

Apparent Diffusion Coefficient

Fractional Anisotropy

T2*

6th July 2009, NZIP6th July 2009, NZIP

Functional MRI of Language – Functional MRI of Language – Passive Listening, RhymingPassive Listening, Rhyming

Magnetic properties of oxyhemoglobin and deoxyhemoglobin Magnetic properties of oxyhemoglobin and deoxyhemoglobin L. Pauling and C. Coryell, PNAS USA 22:210-216 (1936)L. Pauling and C. Coryell, PNAS USA 22:210-216 (1936)

6th July 2009, NZIP6th July 2009, NZIP

Radiation therapyRadiation therapy

Dose

Res

po

nse Tumour

control probability

Normal tissue complication probabilityCure

6th July 2009, NZIP6th July 2009, NZIP

Linear Accelerator (linac)

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Intensity-Modulated Radiotherapy Intensity-Modulated Radiotherapy (IMRT) (IMRT)

Intensity ModulatedBeamProfiles

PatientCross -section

Tumour

HighDoseRegion

Constrained inverse problem

Juergen Meyer, UCLinear Accelerator (linac)

6th July 2009, NZIP6th July 2009, NZIP

SummarySummary Physics has made, and continues Physics has made, and continues

to make essential contributions to to make essential contributions to modern medicinemodern medicine

ImagingImaging X-ray imaging (X-ray imaging (Medipix/MARSMedipix/MARS)) Nuclear imagingNuclear imaging MRI (MRI (Functional imagingFunctional imaging))

Radiation therapyRadiation therapy Accelerator physicsAccelerator physics Treatment planning, Monte Carlo Treatment planning, Monte Carlo

modelingmodeling ““Blue sky” research results in Blue sky” research results in

important unexpected technology important unexpected technology (e.g. PET)(e.g. PET)

Medical physicsMedical physics Excellent career prospectsExcellent career prospects Using physics to improve healthUsing physics to improve health