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Current Topics in Medical Physics Research

Current Topics in Medical Physics Research. Xiaoming Zheng, PhD. School of Dentistry and Health Science Chengdu, China, 2009. Current Research Interests . Image reconstruction algorithms Scatter and resolution corrections Image quality assessment Clinical image analysis

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Current Topics in Medical Physics Research

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  1. Current Topics in Medical Physics Research Xiaoming Zheng, PhD. School of Dentistry and Health Science Chengdu, China, 2009

  2. Current Research Interests • Image reconstruction algorithms • Scatter and resolution corrections • Image quality assessment • Clinical image analysis • Computer aided diagnosis • Radiation detectors

  3. Filtered Back-Projection

  4. Butterworth Filter and Cutoff Frequency

  5. Iterative Reconstruction

  6. Rescaled Block Iterative Reconstruction Algorithm

  7. Attenuation Compensation

  8. Scatter Compensation

  9. Resolution Compensation

  10. Images Reconstructions • Iterative Reconstruction: Rescaled Block Iterative Algorithm including attenuation, scatter, and distance resolution compensation. Parameters tested: iteration 1,3,5,7,10 and post Gaussian filter FWHM 0,1,2,3,4 pixels • Filtered Back-Projection: Parameters tested: Butterworth filter cut-off frequencies: 0.10, 0.15, 0.20, 0.25 and 0.30 pixel-1

  11. Reconstructed images FBP Iterative

  12. Human and Numerical Observer Image Quality Studies • Human observer study using receiver operating characteristics • Numerical observer employing an ideal observer model.

  13. Receiver Operating Characteristics

  14. Numerical Observers

  15. Types of Channels

  16. Numerical Observer Results: RBI

  17. Human Observer Results

  18. Scatter and Cross-talk Correction in Dual Radionuclide Imaging

  19. The Neural Network

  20. Before Correction After Correction

  21. Image Registration

  22. Statistical Parametric Mapping

  23. 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, etc.

  24. CT Scan Parameters and Dose Index Brain Abdomen

  25. CT Dose Index and image quality scores summary

  26. Single Slice CT Images

  27. 16 Slice CT Images

  28. 64 Slice CT Images

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

  30. PET/SPECT Simulation Using GEANT

  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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