Radiation is energy that is sent out from a source. Radiation exposure occurs when a person is exposed to this energy.

There are different forms of radiation. Some come from nature and some are manmade. There are the ultraviolet (UV) rays from the sun. There is also the radiation used in microwaves to heat food. Radiation is divided into:

  • Ionizing radiation—a high-frequency radiation that is able to damage cells, has also been linked to cancer and other health problems
  • Nonionizing radiation—low in frequency and is not known to cause cancer (except for UV rays)
Ionizing Radiation Nonionizing Radiation
Gamma rays Visible light
X-rays Infrared rays
UV rays (high-energy) Microwaves
Sub-atomic particles Radio waves
UV rays (low-energy)

Here we focus on ionizing radiation.

A person can be exposed to ionizing radiation from:

  • X-rays
  • Radiation therapy used to treat certain types of cancer
  • Radioactive elements in the soil or public works systems (eg, water supply)
  • Workplace environment (eg, uranium mines)
  • Radiation from nuclear disasters

External Radiation of a Cancerous Growth
Radiation of Tumor
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