Safety and radioactive sources
Radiation can cause harm to living things, but the dangers can be minimised if the correct precautions are taken.
- The best defence against ionising radiation is distance. The greater the distance, the less chance there is of being exposed to radiation.
- Radioactive sources should be kept away from the body and never brought close to the eyes.
- The time of exposure to ionising radiation should be limited.
- Sources should be shielded from the body and handled using tongs.
- Sources should be stored in lead lined containers to ensure no exposure to the environment whilst in storage.
- Basic safety precautions such as wearing goggles and washing hands after using a radioactive source should be taken.
- The radiation that a person receives can be monitored using film badges.
- All areas containing ionising radiation sources will the show the hazard symbol.
Biological effects of radiation
Ionising radiation can have a significant effect on biological tissue.
Exposing cells to the energy transferred by the radiation will have the following effects on cells:
- Cells can be altered by ionising radiation and change their function.
- Cell can be destroyed by ionising radiations.
- This can lead to the creation of cancer cells.
However, strong and intense bursts of radiation can kill cells allowing radiation to be used to kill cancer cells. This treatment is known as radiotherapy and is prescribed by a specialist cancer doctor called an oncologist.
Destroying cancer cells
Gamma rays can be directed through the body to target tumours that cannot be treated with conventional surgery.
The positioning and the intensity of the gamma ray sources are carefully calculated to ensure that the cancer cells receive enough radiation to kill them whilst the surrounding tissue remains in a healthy condition.
Radioactive tracers
Ionising radiation can also be used to trace blood flow around the body. If a liquid containing a gamma source with a short half-life is injected into your blood, it will travel around your body. Where there is a blockage the activity of the radiation will be highest due to collection of blood. Using a gamma camera - special gamma ray detector - these areas can be located.
Sterilising medical instruments
Medical instruments are too expensive to be thrown away once they have been used, so they are washed several times in very hot water and then resealed in plastic wrapping. Then the whole package is irradiated with a dose of gamma rays. Any bacteria in the container are now destroyed and the instruments remain sterile until the package is opened.
Irradiating food
Foods with a high water and sugar content are often irradiated with gamma radiation to destroy any bacteria which may cause them to spoil quickly. The food does not remain radioactive after exposure to gamma rays, so is safe to eat.
