Dangers and Uses of Radiation

• Radioactive contamination is the unwanted presence of materials containing radioactive atoms on other materials
• The hazard from contamination is due to the decay of the contaminating atoms
• The type of radiation emitted affects the level of hazard
• Irradiation is the process of exposing an object to nuclear radiation
• The irradiated object does not become radioactive
• Background radiation comes from natural sources such as rocks and cosmic rays from space
• Background radiation comes from man-made sources such as the fallout from nuclear weapons testing and nuclear accidents
• The level of background radiation and radiation dose may be affected by occupation and/or location
• Radiation dose is measured in sieverts (Sv)
• 1000 millisieverts (mSv) = 1 sievert (Sv)
• Radioactive isotopes have a very wide range of half-life values
• Nuclear radiations are used in medicine for the

  • Exploration of internal organs
  • Control or destruction of unwanted tissue
• Outside the body alpha radiation is less dangerous because it cannot penetrate through skin
• Outside the body beta and gamma sources are the most dangerous because they can penetrate the body and get to delicate organs
• Inside the body alpha sources are the most dangerous because they highly ionising in a localised area
• Gamma sources are used as medical tracers as they are injected into the body and are followed using an external detector
• Gamma sources are used as medical tracers because the are the least ionising and they should have a short half life
• Gamma rays are used to kill cancer cells without damaging too many normal cells
• Radiation can enter living cells and ionise them causing tissue damage
• Lower doses of radiation can lead to mutant cells which divide uncontrollably which is cancer
• High doses of radiation kill cells completely causing radiation sickness