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External Exposure

External exposure is radiation that comes from somewhere outside the body and interacts with us. The source of radiation can be a piece of equipment that produces the radiation, like an x-ray machine, or it can be from radioactive materials in a container. The exposure occurs when the radiation from these sources interacts with our body and the dose occurs when the radiation leaves some of the energy in our body.

Sources outside the body that emit x or gamma rays can be external radiation exposure hazards. The amount of external radiation exposure you can receive is related to your distance from the source, the energy of the emitted radiation, the total amount of radioactive material present or the machine setting, and the time of exposure.

Alpha and beta particles, in general, constitute no external exposure hazard because the particles generally do not pass through skin. However, high-energy beta particles can cause a large skin dose if allowed to be on the skin for a long time because they will leave much of their energy there.