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Where’s the Physics in Medicine?
Richard Watts Director of MR Research, Van der Veer Institute Dept. of Physics and Astronomy University of Canterbury 6th July 2009, NZIP
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Therapy Diagnostic Imaging Therapy MRI Nuclear Imaging X-Ray
6th July 2009, NZIP
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X-Ray Imaging Contrast: Density, Atomic Number
source Object Detector December 22nd, 1895 Wilhelm Roentgen “Builder survives nailgun accident” Phil and Anthony Butler, UC and MARS Bioimaging
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Pneumoencephalography
Pneumoencephalogram from Moore et al (1935) 'Encephalographic studies in mental disease' - American Journal of Psychiatry 6th July 2009, NZIP
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Medipix – Spectroscopic X-ray Imaging (CERN) Separate Density and Atomic Number
“Colour X-ray Imaging” 6th July 2009, NZIP
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Computed Tomography (CT) 3D X-Ray Imaging
6th July 2009, NZIP
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Computed Tomography (CT) 3D X-Ray Imaging
6th July 2009, NZIP
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Computed Tomography (CT) 3D X-Ray Imaging
Prototype MARS Spectroscopic CT scanner 6th July 2009, NZIP CT Scanner rotating
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Nuclear Imaging, Gamma Camera (1957) Contrast: Concentration of radiopharmaceutical
6th July 2009, NZIP
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Radiopharmaceuticals for Nuclear Imaging
Parent Decay Mode Half-life Daughter Decay Product 69Ge Germanium EC 271 days 68Ga Gallium β+, EC 68 min 68Zn Zinc 81Rb Rubidium 4.5 hr 81mKr Krypton IT 13.5 s 81Kr 82St Strontium 25.5 days 82Rb β+ 75 s 82Kr 99Mo Molybdenum β- 67 hr 99mTc Technetium 6 hr 99Tc EC = Electron capture, IT = Isometric transition 6th July 2009, NZIP
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Single Photon Emission Computed Tomography, SPECT 3D Nuclear Imaging
6th July 2009, NZIP Bushberg, Essential Physics of Medical Imaging
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Positron Emission Tomography (PET)
6th July 2009, NZIP 18F-FDG, T1/2 ~ 2 hours
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Magnetic Resonance Imaging, (n)MRI
“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 Hydrogen Nuclei are aligned by a big Magnetic Field Resonant frequency given by Larmor equation Nuclei absorb radiofrequency energy at that frequency and then re-emit energy Magnetic field gradient coils allow the field (and resonant frequency) to vary with location in x,y,z – Imaging 6th July 2009, NZIP
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Guess who? 6th July 2009, NZIP
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Structural Brain Imaging with MRI
T2 FLAIR Apparent Diffusion Coefficient Fractional Anisotropy T2* 6th July 2009, NZIP
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Functional MRI of Language – Passive Listening, Rhyming
Magnetic properties of oxyhemoglobin and deoxyhemoglobin L. Pauling and C. Coryell, PNAS USA 22: (1936) 6th July 2009, NZIP
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Normal tissue complication probability Tumour control probability
Radiation therapy Normal tissue complication probability Tumour control probability Cure Response Dose 6th July 2009, NZIP
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Linear Accelerator (linac)
6th July 2009, NZIP
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Intensity-Modulated Radiotherapy (IMRT)
High Dose Region Constrained inverse problem Tumour Inverse planning Optimization Ill-posed problem -> find best trade-off Patient Intensity Modulated Cross - section Beam Profiles 6th July 2009, NZIP Linear Accelerator (linac) Juergen Meyer, UC
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Summary Physics has made, and continues to make essential contributions to modern medicine Imaging X-ray imaging (Medipix/MARS) Nuclear imaging MRI (Functional imaging) Radiation therapy Accelerator physics Treatment planning, Monte Carlo modeling “Blue sky” research results in important unexpected technology (e.g. PET) Medical physics Excellent career prospects Using physics to improve health 6th July 2009, NZIP
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