irradiation and contamination

• background radiations come from...

  many sources

  - naturally occurring unstable isotopes (in the air, food, building materials, rocks)

  - radiation from space (cosmic rays that the atmosphere protects us from)

  - human activity (e.g. fallout from nuclear explosions, nuclear waste, medical practices)
• background radiation


  low-level nuclear radiation that occurs naturally in the environment
• your exposure to background radiation is affected by...

  your location and occupation
• radiation dose


  amount of ionising radiation a person receives, measured in sieverts (Sv)
• what is likely to happen to cells if they receive a high dose of nuclear radiation?

  cells will be killed
• why is nuclear radiation dangerous?

  because it is ionising and can damage cells
• irradiation


  exposure to any form of radiant energy such as light, heat, or x-rays
• does irradiating something make it radioactive?


  no
• ways of reducing irradiation

  - keeping sources in lead-lined boxes

  - standing behind barriers

  - being in a different room

  - using remote controlled arms
• safety precautions to take when handling radioactive sources

  - handle source with tongs or gloves: never allow source to touch skin

  - never have source outside of lead lines box for longer than necessary
• contamination


  when unwanted radioactive substances get into/onto an object
• irradiation and contamination difference

  irradiation is exposure to radioactivity whereas contamination is when a radioactive source is on or inside an object

  - an irradiated object will not emit radiation while a contaminated object does
• what radiation source is most dangerous outside of the body?

  beta and gamma, because they have penetrate the body and get to delicate organs
• what radiation source is most dangerous inside of the body?

  alpha, because they do all their damage in a very localised area
• medical tracers


  certain radioactive isotopes can be injected into people (or swallowed) and their progress around the body can be followed using an external detector; a computer converts the reading to a display showing where the strongest reading is coming from
• radiotherapy


  since high doses of ionising radiation will completely kill living cells., it is used to treat cancer. they are directed at the cells at a certain dosage so normal cells are not affected. (a small amount of damage to normal cells is inevitable)
• risks to using radiation

  - it can enter cells and ionise atoms and molecules (it can lead to tissue damage).

  - lower doses causes minor damage without killing cells, this can cause mutant cells which lead to cancerous cells.

  - higher doses kill cells completely, causing radiation sickness