1. Medical Imaging Mohammad Dawood Department of Computer Science University of Münster Germany

2. 2 Medical Imaging, SS-2010 Mohammad Dawood 2 Medical Imaging, SS-2010 Mohammad Dawood Medical Imaging Modalities

3. 3 Medical Imaging, SS-2010 Mohammad Dawood Introduction to Medical Imaging Modalities 1.X-Ray 2.CT 3.MRT 4.SPECT 5.PET 6.Ultrasound 7.…

4. 4 Medical Imaging, SS-2010 Mohammad Dawood Electro-Magnetic Radiation

5. 5 Medical Imaging, SS-2010 Mohammad Dawood

6. 6 Medical Imaging, SS-2010 Mohammad Dawood X-Ray CTMRT

7. 7 Medical Imaging, SS-2010 Mohammad Dawood X-Ray

8. 8 Medical Imaging, SS-2010 Mohammad Dawood Production of X-Rays in Medical Diagnostic Cathode is heated Electrons are accelerated in an electric field Anode is used as target

9. 9 Medical Imaging, SS-2010 Mohammad Dawood X-Rays produced when high velocity electrons collide with matter Bremsstrahlung Compton Scatter

10. 10 Medical Imaging, SS-2010 Mohammad Dawood X-Rays 99% of the energy is converted into heat -> targets with high melting points and atomic numbers Rotating Anodes 3000-17000 rpm Tungsten (Z=74, T m =2757°, λ=1.3) Rhenium (Z=75, T m =2557°, λ=0.7)

11. 11 Medical Imaging, SS-2010 Mohammad Dawood X-Rays Attenuation effect

12. 12 Medical Imaging, SS-2010 Mohammad Dawood X-Rays Attenuation effect Wavelength Atomic Number Density Thickness

13. 13 Medical Imaging, SS-2010 Mohammad Dawood

14. 14 Medical Imaging, SS-2010 Mohammad Dawood Mammography

15. 15 Medical Imaging, SS-2010 Mohammad Dawood X-Rays Contrast agents

16. 16 Medical Imaging, SS-2010 Mohammad Dawood X-Rays Hounsfield scale (HU) Scatter Ray hardening

17. 17 Medical Imaging, SS-2010 Mohammad Dawood CT (Computed Tomography)

18. 18 Medical Imaging, SS-2010 Mohammad Dawood CT (Computed Tomography) Based on X-rays and attenuation effect

19. 19 Medical Imaging, SS-2010 Mohammad Dawood CT (Computed Tomography) 1 st Generation CT Point by point 2 nd Generation Detector array 3 rd Generation Extended FOV 4 th Generation Detector ring Electron Beam CT

20. 20 Medical Imaging, SS-2010 Mohammad Dawood

21. 21 Medical Imaging, SS-2010 Mohammad Dawood CT scanner The gantry

22. 22 Medical Imaging, SS-2010 Mohammad Dawood

23. 23 Medical Imaging, SS-2010 Mohammad Dawood MRT (Magnetic Resonance Tomography)

24. 24 Medical Imaging, SS-2010 Mohammad Dawood MRT (Magnetic Resonance Tomography Based on the spin of protons and an external magnetic field - Nuclei with odd number of protons have a spin - Due to electric charge they act as dipoles

25. 25 Medical Imaging, SS-2010 Mohammad Dawood MRT (Magnetic Resonance Tomography - dipoles are randomly distributed - When an external magnetic field (B 0 ) is present the dipoles align themselves parallel or anti-parallel to it - more often parallel than anti-parallel 100,000:100,006 at 1.5 Tesla

26. 26 Medical Imaging, SS-2010 Mohammad Dawood MRT (Magnetic Resonance Tomography -the spins are not aligned exactly 0° or 180° to B 0 - this leads to a precession - Larmor frequency

27. 27 Medical Imaging, SS-2010 Mohammad Dawood MRT (Magnetic Resonance Tomography) -net spin vector parallel to B 0

28. 28 Medical Imaging, SS-2010 Mohammad Dawood MRT (Magnetic Resonance Tomography) - external RF signal (at larmor frequency) causes flip of M

29. 29 Medical Imaging, SS-2010 Mohammad Dawood MRT (Magnetic Resonance Tomography) appropriate external RF signal (at larmor frequency) causes flip of M into x-y plane precession induces a signal in a receiver coil T 1 : time for re-alignment with B 0 after the RF signal to 63%, usually in seconds

30. 30 Medical Imaging, SS-2010 Mohammad Dawood MRT (Magnetic Resonance Tomography - T 2 and T 2 * decay : time for decay to 37% in transverse magnetization, usually in milliseconds

31. 31 Medical Imaging, SS-2010 Mohammad Dawood MRT (Magnetic Resonance Tomography Selective Phase coding Frequency coding

32. 32 Medical Imaging, SS-2010 Mohammad Dawood