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Basics of Radiation



Safety Around Radiation Sources

Types of Radiation Exposure

Managing Radiation Emergencies

Procedure Demonstration


Radiation research technician

Radiation is used in research.

Basics of Radiation

Radiation is energy that comes from a source and travels through some material or through space. Light, heat and sound are types of radiation. The kind of radiation discussed in this presentation is called ionizing radiation because it can produce charged particles (ions) in matter.

Ionizing radiation is produced by unstable atoms. Unstable atoms differ from stable atoms because they have an excess of energy or mass or both.

Unstable atoms are said to be radioactive. In order to reach stability, these atoms give off, or emit, the excess energy or mass. These emissions are called radiation. The kinds of radiation are electromagnetic (like light) and particulate (i.e., mass given off with the energy of motion). Gamma radiation and X-rays are examples of electromagnetic radiation. Beta and alpha radiation are examples of particulate radiation. Ionizing radiation can also be produced by devices such as X-ray machines.


Radiation exposure occurs by diagnostic X-ray. Irradiation by machine-generated radiation occurs only when the machine is turned on.

 X-ray machine

There is also natural background radiation exposure. It comes from cosmic rays and from naturally occurring radioactive materials contained in the earth and in living things.


Irradiation is exposure to penetrating radiation. Irradiation occurs when all or part of the body is exposed to radiation from an unshielded source. External irradiation does not make a person radioactive.

Radioactive Contamination

Contamination occurs when material that contains radioactive atoms is deposited on skin, clothing, or any place where is it not desired. If is important to remember that radiation does not spread or get "on" or "in" people; rather it is radioactive contamination that can spread. A person contaminated with radioactive materials will be irradiated until the source of radiation (the radioactive material) is removed.

  • A person is externally contaminated if radioactive material is on skin or clothing.
  • A person is internally contaminated if radioactive material is breathed in, swallowed, or absorbed through wounds.
  • The environment is contaminated if radioactive material is spread about or uncontained.

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