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Medical Imaging: the Glass Patient Prof.dr.ir. Bart M. ter Haar Romeny Technische Universiteit Eindhoven Dept. of Biomedical Engineering
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Image Acquisition Techniques Classical X-Ray Classical X-Ray Computed Tomography Computed Tomography Nuclear Medicine Nuclear Medicine Ultrasound Ultrasound Magnetic Resonance Imaging Magnetic Resonance Imaging
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28 December 1895 Prof. Röntgen presenting his invention at Würzburg, 23 January 1896
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The first X-ray ever: the hand of Röntgen’s wife, end 1895. One of the first medical examples: a shot of hail in a hand, 1896
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Anode connection + kV Filament connection High Voltage supply + - Principle of the X-ray tube: The kinetic energy of the electrons is released by the collision at the anode. The tube is vacuum. vacuum Tungsten anode cathode X-rays output
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Classical X-ray images
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Fluoroscopy with the image intensifier during angioplasty: Real-time visualization of catheters and vessels. Image intensifier X-ray tube High voltage generator
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DSA = Digital Subtraction Angiography = Röntgen X-ray with contrast in vessels Dotter procedure: Blow up balloon in obstructed vessel
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Tomoscan AV EasyVision CT = Computed Tomography = Röntgen X-ray slices 3D Greek = to cut, to slice
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CT: solve for 512x512 pixels by 512x512 equations CT: solve for 512x512 pixels by 512x512 equations Result: a slice Result: a slice
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Examples CT
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3D visualization Simulation of the physics of light reflection (ray casting/tracing) “2.5D” image
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Nuclear Medicine Principle: Instable radioactive isotopes are made, and build in a pharmacon Instable radioactive isotopes are made, and build in a pharmacon Patient gets contrast medium injected, which specifically stores in tissue Patient gets contrast medium injected, which specifically stores in tissue Signal position is measured with a gamma-camera Signal position is measured with a gamma-camera
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Ionizing radiation: GAMMA When the nucleus gets too large, the “strong force” is not strong enough to compensate the repulsive force of the protons Alpha radiation: He nuclei (come only microns far in tissue) Beta radiation: electrons (come only cm far in tissue) Gamma radiation: high energy photons (easily go through tissue) GAMMA photon(s)
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Nuclear Imaging Camera 3-rotating-head SPECT scanner SPECT = Single Photon Emission Computed Tomography
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PET = Positron Emission Tomography No taskDuring task Positron = anti-electron When it meets an electron → annihilation (explosion) Two photons go in opposite direction, ring coincidence detector
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Molecular Imaging Nano-vesicles: - antibody bindings - 90.000 Gadolinium atoms - container for pharmaca - break by US shockwave - less side effects - chemotherapy on target Highly specific tracer biomolecules
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Ultrasound Kretz Medicor 530D
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F 0 F 1 skin vessel (red) bloodcells F d = F 0 - F 1 = 2 x V x cos c V F d = Doppler (‘difference’) frequency transducer Doppler
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3D ultrasound
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Magnetic Resonance Imaging (MRI) X Y Z ( ) Receiver Coil
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Philips Medical Systems 1000 x 1000 pixels = 1 million measurements
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Superconducting Magnet
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MR Angiography Excitation only of a thin slice Non excited blood flows in the slice Readout of little ‘zero-signal’ areas For all slices → angiogram
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Why so many imaging modalities? Choice modality: Tissues have different properties for different physical interactions Choice modality: Tissues have different properties for different physical interactions Contrast: Tissue types differ in one or more of these properties Contrast: Tissue types differ in one or more of these properties Anatomical imaging versus functional imaging Anatomical imaging versus functional imaging CT MR
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Anna Vilanova, Vienna TU / TUE - BMT Univ. of Dusseldorf Philips Medical Systems A new 3D technique: Virtual endoscopy
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New Eyes are assisting the Radiologist The overwhelming amount of data calls for condensed presentation and analysis Philips Medical Systems Vital Images Groeller - TU Vienna
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Image Guided Surgery
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Bev Doolittle: The forest has eyes Physics everywhere Image Acquisition Pattern recognition Computer aided diagnosis Biomedical research New researchers Strong benefit for the patient
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