Exposure to Radiation

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There are two basic types of radiation: ionizing and non-ionizing. Examples of non-ionizing radiation include microwaves and electromagnetic fields. Types of ionizing radiation include gamma, beta and x-rays. Radiation therapy treatments involve one or more of these three types of ionizing radiation.

Ionizing radiation can't be detected with any of the five human senses. Because of this, special instruments, such as Geiger counters and ionization chambers, are used to detect radiation and to measure radiation levels. Exposure to radiation doesn't cause people to glow in the dark or make them radioactive.

Everyone is exposed to radiation everyday. Most of this "non-occupational" radiation exposure comes from natural sources. The table below lists sources and average exposures from both natural and man-made sources of radiation:

Natural Sources Man-made Sources

Cosmic (from outer space) = 8%

Medical (x-rays and nuclear medicine) = 15%

Internal (in the body) = 11%

Nuclear weapon testing = 0.3%

terrestrial (in the environment) = 8%

Nuclear power = 0.1%

Radon gas (in houses and buildings) = 55%

Consumer products (camera lens, natural gas, building materials) = 3%

Source: National Council on Radiation Protection and Measurements Report No. 93

Non-Occupational Exposure

Radon ~ 200 mrem
Terrestrial ~ 28 mrem
Cosmic ~ 26 mrem
Internal (K-40) ~ 26 mrem
Medical ~ 10 mrem
Dental ~ 5 mrem
Fallout from Weapons Testing < 0.3 mrem
TOTAL ~ 300 mrem

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