Medical Applications of Nuclear Physics

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					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, 7th 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
 Positron Emission Tomography
 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, 5th 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

 Magnetic Resonance Imaging
 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, 5th 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)

				
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