Medical Imaging: the Glass Patient Prof.dr.ir. Bart M. ter Haar Romeny Technische Universiteit Eindhoven Dept. of Biomedical Engineering

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

28 December 1895 Prof. Röntgen presenting his invention at Würzburg, 23 January 1896

The first X-ray ever: the hand of Röntgen’s wife, end One of the first medical examples: a shot of hail in a hand, 1896

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

Classical X-ray images

Fluoroscopy with the image intensifier during angioplasty: Real-time visualization of catheters and vessels. Image intensifier X-ray tube High voltage generator

DSA = Digital Subtraction Angiography = Röntgen X-ray with contrast in vessels Dotter procedure: Blow up balloon in obstructed vessel

Tomoscan AV EasyVision CT = Computed Tomography = Röntgen X-ray slices  3D Greek  = to cut, to slice

CT: solve for 512x512 pixels by 512x512 equations CT: solve for 512x512 pixels by 512x512 equations Result: a slice Result: a slice

Examples CT

3D visualization Simulation of the physics of light reflection (ray casting/tracing) “2.5D” image

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

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)

Nuclear Imaging Camera 3-rotating-head SPECT scanner SPECT = Single Photon Emission Computed Tomography

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

Molecular Imaging Nano-vesicles: - antibody bindings Gadolinium atoms - container for pharmaca - break by US shockwave - less side effects - chemotherapy on target Highly specific tracer biomolecules

Ultrasound Kretz Medicor 530D

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

3D ultrasound

Magnetic Resonance Imaging (MRI) X Y Z (   ) Receiver Coil

Philips Medical Systems 1000 x 1000 pixels = 1 million measurements

Superconducting Magnet

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

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

Anna Vilanova, Vienna TU / TUE - BMT Univ. of Dusseldorf Philips Medical Systems A new 3D technique: Virtual endoscopy

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

Image Guided Surgery

Bev Doolittle: The forest has eyes Physics everywhere Image Acquisition Pattern recognition Computer aided diagnosis Biomedical research New researchers Strong benefit for the patient