Medical applications of nuclear physics
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Medical applications of nuclear physics Presentation Transcript

  • 1. Medical Applications of Nuclear Physics
  • 2. Nuclear Physics Medical Applications Diagnostic Imaging
  • 3. The First “Medical Application” Source:Radiological Society of North America, Inc (http://www.radiologyinfo.org)
  • 4. CAT scan Computerized Axial Tomography Source: Cutnell and Johnson, 7 th edition image gallery
  • 5. CAT scan
    • X-rays are produced and emitted in thin, fanned out beams
    • Detected on the opposite side of the patient via arrays of x-ray detectors
    • Scanner rotates to get the full 2-D picture
    • The patient is passed through the scanner in small steps to get ‘slices’ for 3-D reconstruction
    • Computer control allows for high level of precision yield very detailed images
  • 6. CAT scan advantages
    • 3-D reconstruction of the internal organs
    • High resolution giving doctors very good details prior to grabbing a knife
    • CAT scans can image soft tissue, bone, and blood vessels at the same time
    • Often less expensive than an MRI and can be used with medical implants and metal objects
    Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
  • 7. CAT scan reconstructed Source: Cutnell and Johnson, 7th edition image gallery
  • 8. CAT scan image of lung Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
  • 9. CAT scan dangers
    • Increased exposure to x-ray radiation
    • NBC Nightly News recently reported on an article in the New England Journal of Medicine that up to as much as 2% of new cancer cases may be caused by CT scans
    • A CT scan of the chest involves 10 to 15 millisieverts versus 0.01 to 0.15 for a regular chest X-ray
    • Nevertheless, it’s still a powerful tool … just don’t over use it.
    Source: http://www.msnbc.msn.com/id/22012569/
  • 10. PET scan
    • P ositron E mission T omography
    • A radioactive source (positron emitter) is injected into the patient usually attached to a sugar
    • Cancers have unusually high metabolic rates so the sugar solution goes more to the cancer cells than the other tissues
    • Emitted positron annihilates with an electron to produce two gamma rays
    • Gamma rays leave traveling in opposite directions
    • Coincident detection of gamma rays can be computer reconstructed to give high resolution images of the internal organs
    Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org) Source: Cutnell and Johnson, 5 th edition text
  • 11. PET scan advantages
    • Very powerful imaging tool
    • Produces higher resolution images
    • Can detect changes in metabolic activity before changes in the anatomy are seen in CAT and MRI images
    • Can be used in combination with CT and MRI images (CT/PET scans are becoming more widely used)
    Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
  • 12. PET scanner Source: Cutnell and Johnson, 7th edition image gallery
  • 13. PET scan image Source: Cutnell and Johnson, 7th edition image gallery
  • 14. CAT/PET scan combined Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
  • 15. PET scan dangers and limitations
    • PET scan dosages are very small (it’s an efficient method for imaging) but its still radiation
    • Must weigh the danger against the rewards
    • These radio-nuclides have short half-lives which means they must be produced locally or pay huge shipping costs
    • Sometimes gives false positives if there is chemical imbalances in the patient
    Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
  • 16. MRI imaging
    • M agnetic R esonance I maging
    • Patient is placed in a powerful non-uniform magnetic field
    • A electromagnetic wave is transmitted into the body and at the right frequency it is absorbed. This absorption is detected by the machine.
    • A computer reconstructs the location of the cells to develop 3-D images
    Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org) Source: Cutnell and Johnson, 5 th edition
  • 17. MRI imaging machine Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
  • 18. MRI image of the knee Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
  • 19. MRI dangers and limitations
    • Confined environment
    • No metals allowed!
    • Does not do well with lungs
    • The patient must lie perfectly still so anxiousness may make the images blurry
    • MRI’s can be expensive
  • 20. Nuclear Physics Medical Applications Treatments
  • 21. Gamma Knife Radio surgery
    • Use of gamma rays to treat cancerous tumors
    • Directs gamma radiation from many directions to a specific location to delivery a powerful dose of radiation
    • Does not require surgery
    • Can treat cancers where conventional surgery is not possible
    Source: Cutnell and Johnson, 7th edition image gallary
  • 22. Gamma Knife device Source: Cutnell and Johnson, 7th edition image gallery
  • 23. Gamma Knife disadvantages
    • Exposure to significant radiation
    • Must be aligned to within a millimeter for accurate treatment
    • Is not guaranteed to destroy all the cancer (it’s a treatment, after all)
    Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
  • 24. Linear Accelerator
    • High energy electrons are crashed into a heavy metal target and emit x-rays
    • Energy, intensity, and location of the x-rays are controlled to deliver radiation to a tumor
    • Precision and accuracy are very good and getting better
    Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
  • 25. Linear Accelerator in Operation Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
  • 26. Linear Accelerator Drawbacks
    • X-ray radiation can damage healthy tissue
    • Must be aligned correctly for good accuracy
    • Movement of internal organs requires larger beam area to get the cancer … you don’t want to do this again
    • Equipment is expensive … but getting much better
  • 27. Proton Therapy
    • Similar to the linear accelerator therapy except energetic protons are directed at the tumor
    • Varying the energy of the protons results in good deep control
    • Can be focused to the size of a pin
    • Usually results in less damage to healthy tissue
    Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
  • 28. Proton Therapy Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
  • 29. Proton Therapy Disadvantages
    • Radiation exposure to good tissues
    • Requires the cancer to remain still for good precision and minimization of collateral damage
    • Very expensive and only used at a few locations in North America
    Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)