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Effects_of_Radiation_and_Its_Uses

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					Radiation and Its Uses
      Pg. 886-889
       Effects of Radiation
• Radioactive elements are potentially
  hazardous, but the effects are quite
  subtle
  • The effects of exposure to radiation may
    not be apparent for years!
       Effects of Radiation
• Radiation damage can be classified in
  two groups:
  • Somatic Damage: damage to the
    organism itself, resulting in sickness or
    death
     • Will appear immediately if a massive dose of
       radiation is received
     • Takes years to appear if smaller doses are
       received, usually in the form of cancer
  • Genetic Damage: damage to the genetic
    machinery of the reproductive cells
     • Creates problems that are seen in the offspring
       of the organism
                Effects of Radiation

• Factors that affect the
  biological effects of
  radiation:
  • Energy of the radiation
     • The higher the energy of
       the radiation, the more
       damage it can cause
  • The penetrating ability
    of the radiation
         Effects of Radiation
• Factors that affect the biological effects of
  radiation:
   • 1. The ionizing ability of radiation
      • Gamma can penetrate deeply, but only causes
        occasional ionization
      • Alpha cannot penetrate as well as gamma, but is very
        effective in causing ionization, which causes major
        damage
   • 2. The chemical properties of the radiation
     source
      • How long it stays in the body determines how much
        damage can be done
         • Example: Both Kr-85 and Sr-90 decay by beta emission
             • Kr-85 is a noble gas and is chemically inert, so it will
               pass through the body quicker than Sr-90
Let’s figure out how much radiation you are exposed to annually

      • Information you will need:
          • We are 580ft above sea level
              • (Salt Lake City, Utah is 4300ft above sea
                level)
          • Nearest nuclear power plants:
              • Joliet (64 miles away)
              • Rockford (75miles away)
          • Nearest Coal-fired power plant
              • Waukegan (18miles away)
Effects of Short-Term Exposures to Radiation

Rem indicates the danger the radiation poses for
  humans.
Dose (rem)        Clinical Effect
0-25              Nondetectable
25-50             Temporary decrease in white
                  blood cell counts
                  Strong decrease in white blood
100-200
                  cell counts
                  Death of half the exposed
500               population w/in 30 days
        Uses of Radiation
1.   Smoke detectors
2.   Neutron Activation
3.   Radioactive tracers
4.   Cancer Treatment
Why is my smoke detector radioactive?




  No smoke               Smoke present
                     Using Radiation
• Neutron Activation:
  • Sample of interest is hit with neutrons from a radioactive
    source
     • Causes some atoms to become radioactive
     • Half-life and type of radiation emitted is measured by a computer
         • Each atom has specific characteristics
     • Can determine elements in original sample
  • Used for:
     • Detection of art forgeries
     • Gunpowder residue analysis
Ways to use Radioactive tracers :
    #1. Learning reaction pathways

      O                    +       O
                       H
    R C OH +   H OR'           R   C O R' + H O H
Ways to use Radioactive tracers :
#2. Reading DNA
   Ways to use Radioactive tracers :


#3. Material Flow
Ways to use Radioactive tracers :
       #4. Medical Diagnosis
                                              •Patient drinks a sample with a
                                              small amount of radioactive
                                              iodine – 131
                                              •Thyroid uses iodine to make
                                              thyroxine
                                              •After two hours, uptake of
 asymmetric scan            normal            iodine is measured by scanning
 indicates disease                            with a radiation detector




   PET and brain activity.
•Other examples:
   •Technetium-99m used
   to detect brain tumors
   and liver problems
   •Phosphorus-32 used               normal                  Alzheimer’s
   to detect skin cancer
         Using Radiation to Help Us
• Cancer Treatment
  • Beams of gamma radiation
    are targeted at the growing
    tumor
  • Can kill healthy cells along
    with cancerous cells
     • However, healthy cells resist
       treatment more than cancer
       cells
  • Cancerous cells in the
    middle of the tumor may be
    immune to the gamma
    radiation
  • Common isotopes used:
     • Cobalt-60 and Cesium-137
          Using Radiation
• Cancer Treatment continued:
  • Salts of radioisotopes can also be used
    •   Sealed in gold tubes
    •   Implanted into the tumor
    •   Emit beta and gamma radiation
    •   Sealed container prevents them from traveling
        throughout the body
Proton Therapy:




   http://www.proton-therapy.org/index.html
   http://www.niu.edu/protontherapy/index.shtml

				
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posted:6/13/2013
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