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Topics in Medical Physics

Topics in Medical Physics. Xiaoming Zheng, PhD. School of Dentistry and Health Sciences December 2009, Chengdu. Medical Physics at CSU. Major medical imaging modalities Physics in nuclear medicine Magnetic resonance imaging Physics in computed tomography Ultrasound physics

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Topics in Medical Physics

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  1. Topics in Medical Physics Xiaoming Zheng, PhD. School of Dentistry and Health Sciences December 2009, Chengdu.

  2. Medical Physics at CSU • Major medical imaging modalities • Physics in nuclear medicine • Magnetic resonance imaging • Physics in computed tomography • Ultrasound physics • Health physics.

  3. Major Imaging Modalities

  4. Typical CT Images

  5. Positron Emission Tomography

  6. On Site Cyclotron

  7. Whole Body PET Images

  8. Magnetic Resonance Imaging

  9. MRI Radio Frequency Coils

  10. MRI Pulse Sequence

  11. MRI Tissue Contrast Images

  12. Ultrasound Imaging

  13. Ultrasound Image

  14. Medical Physics Research Topics • Image reconstruction algorithms • Scatter and resolution corrections • Image quality assessment • Clinical image analysis • Computer aided diagnosis • Radiation Detectors

  15. Filtered Back-Projection

  16. Butterworth Filter and Cutoff Frequency

  17. Iterative Reconstruction

  18. Rescaled Block Iterative Reconstruction Algorithm

  19. Attenuation Compensation

  20. Scatter Compensation

  21. Resolution Compensation

  22. PET simulation using GEANT

  23. Problems in Dual Radionuclide Imaging: Scatter and Cross-talk

  24. The Neural Network

  25. Receiver Operating Characteristics

  26. Numerical Observers

  27. Image Registration Composite using intensity- based registration Composite using point- based registration

  28. Brain Activation Mapping

  29. Radiation Dose Optimization in CT • Biological effect of ionizing radiation • Cancer rate vs radiation dose • Radiation dose reduction: image quality vs radiation dose • Technical parameters: kVp, mAs,

  30. Computer Assisted Diagnosis • Provide second opinion to radiologists. • FDA approved systems include breast and lung cancer detections. • Image processing • Image data base • Artificial intelligence.

  31. Radiation Detectors • Room temperature Semiconductor Detectors: Materials and mechanisms • Magnetic resonance coils designs.

  32. Scintillator-based gamma camera Detector head (GE Medical Systems)

  33. CZT / NaI comparison ELGEMS CZT pixilated small field imager Anger camera (NaI) Test image Thyroid phantom

  34. Semiconductor - CZT g CdZnTe: Gamma rays create electron/hole pairs. The gamma energy level is proportional to the electrical current. X CdZnTe (CZT) E h + e -

  35. The GaAs detectors

  36. Hybrid Modalities – PET/CT

  37. Hybrid Imaging Systems

  38. New Imaging Systems • New detector technology. • Optical imaging: visible, ultraviolet, inferred. • Molecular imaging: PET, fMRI, Optical • Hybrid imaging systems. • T Herts imaging.

  39. Optical Imaging

  40. Teraherts Imaging

  41. Thickness of tissue probed 30 mm 100mm 1mm 1cm 10cm l 400 nm 800 nm 1600 nm 10 mm 100 mm Confocal/ multi-photon microscopy Diffuse optical tomography Optical coherence tomography Thermography THz imaging

  42. Magnetoencephalography

  43. Medical Physics Topics? • Treatment of depression: Transcranial magnetic stimulation. • Killing of cancer cells: Electric field on biological molecules.

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