Medical applications of nuclear physics

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Medical applications of nuclear physics

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

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