General

• Sources of background radiation

  • Rocks
  • Cosmic rays from space
  • Nuclear weapon testing
  • Nuclear accidents
• How to deal with background radiation in calculations

  Subtract the background count from any readings before calculations (half life etc.) are attempted
• Unit used to measure radiation dosage

  Sieverts (Sv)
• Relationship between sieverts and millisieverts

  1000 millisieverts = 1 sievert
• Reasons why radiation dosage may differ for different people

  • Some occupations involve working with radiation
  • Background radiation differs with location due to things such as the locality of nuclear power stations or radiation related testing
• Factor that determines how dangerous a particular radioactive isotope is

  The half-life of the isotope
• Isotopes with long half-lives are particularly harmful because they remain radioactive for much longer periods of time and must be stored in specific ways to avoid humans and the environment from being exposed to radiation for too long
• Uses of nuclear radiation in medicine

  • Examining of internal organs
  • Controlling and destroying unwanted tissue
• How radiation is used in sterilisation

  Gamma emitters are used to kill bacteria/parasites on equipment
• Radiotherapy process

  1. Gamma emitters direct gamma rays at the cancerous cells

  2. The cancerous cells absorb the radiation and are killed
• Criteria for choosing medical tracers

  • They should have a short half life and decay into a stable isotope which can be excreted
  • They should only release gamma radiation since it is weakly ionising and can easily pass through body tissue without damaging it