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

    • Medical Applications of Nuclear Physics
    • Nuclear Physics Medical Applications Diagnostic Imaging
    • The First “Medical Application” Source:Radiological Society of North America, Inc (http://www.radiologyinfo.org)
    • CAT scan Computerized Axial Tomography Source: Cutnell and Johnson, 7 th edition image gallery
    • 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
    • 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)
    • CAT scan reconstructed Source: Cutnell and Johnson, 7th edition image gallery
    • CAT scan image of lung Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
    • 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/
    • 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
    • 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)
    • PET scanner Source: Cutnell and Johnson, 7th edition image gallery
    • PET scan image Source: Cutnell and Johnson, 7th edition image gallery
    • CAT/PET scan combined Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
    • 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)
    • 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
    • MRI imaging machine Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
    • MRI image of the knee Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
    • 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
    • Nuclear Physics Medical Applications Treatments
    • 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
    • Gamma Knife device Source: Cutnell and Johnson, 7th edition image gallery
    • 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)
    • 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)
    • Linear Accelerator in Operation Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
    • 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
    • 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)
    • Proton Therapy Source: Radiological Society of North America, Inc (http://www.radiologyinfo.org)
    • 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)