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  1. Give the effective half life equation?
    • 1/Te = 1/Tb + 1/Tp
    • effective = biological + physical
  2. Why is the effective half life shorter than the physical and biological half lives?
    This is because the radioactive and biological process are working at the same time.
  3. What is the definition of half life?
    The time it takes for the activity of the material to decrease by half.
  4. What is the difference between external and internal radiotherapy?
    Internal radiotherapy is when a radioactive substance is placed inside the body. External radiotherapy is when a source of radiation is directed at the tumour from outside of the body.
  5. What can radiotherapy be used to treat?
    • Radiotherapy can be used to treat:
    • . Cure cancer
    • . Alleviate the effect of cancer
    • . shrink a tumour prior to surgery
    • . kill and remaining cancer cell after surgery
    • . total body radiation
  6. What are the properties that mean that Iridium 192 can be used as a implant?
    • . Emits alpha and beta radiation.
    • . Has a half life of 74 days long enough for treatment
    • . Placed into a test tube into the breast to remove breast cancer cells.
  7. Why is technetium 99 a perfect tracer?
    • . Emits gamma radiation
    • . half life of 6 hours - long enough to penetrate the body and be detected by the camera, short enough to not cause harm.
    • . Can add an anti body to the organ affinity to make a immunoradioisotope
  8. What are the properties of iodine 131 as an implant?
    • . Emits alpha or beta radiation.
    • . Half life of 8 days.
    • . Organ affinity (used to treat thyroid cancer).
  9. What are the properties of cobalt 60 as a tracer?
    • . Emits gamma radiation
    • . half life of 5 years
  10. How do you test for types of radiation emitted?
    • 1. The first thing is to test the background radiation with a Geiger counter.
    • 2. Move the radioactive substance further back from the Geiger counter, then measure the radiation.
    • 3. If the Geiger counter has dropped to 0 then it's alpha radiation, if the Geiger counter is still measuring then its beta or gamma radiation.
    • 4. Then place aluminium in front of the radioactive substance. If the Geiger counter drops to 0 then its beta radiation, if  the Geiger counter is still measuring then it's gamma radiation.
    • 5. To check this then place a piece of lead in front of the radioactive source, if the Geiger counter drops to 0 then it's gamma radiation.
Card Set:
2014-05-12 12:24:45
Unit medical physics radiotherapy radioisotope

Medical physics radioisotope
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