Ionizing Radiation
Ionizing radiation is energy in the form of waves or particles that has enough energy to remove electrons from atoms. Types of ionizing radiation include alpha, beta, and neutron particles, as well as gamma rays and X-rays. Ionizing radiation can come from natural or human-made sources.
Different types of ionizing radiation have different penetrating abilities.
- Alpha particles: These are energetic, positively charged particles consisting of two protons and two neutrons. External exposure (external to the body) is of far less concern than internal exposure, because alpha particles lack the energy to penetrate the outer dead layer of skin.
- Beta particles: These particles are fast-moving electrons emitted from the nucleus during radioactive decay. Some beta particles can penetrate the skin and cause radiation damage, such as skin burns. However, as with alpha-emitters, beta-emitters are most hazardous when they are inhaled or ingested.
- Gamma rays: Like visible light and X-rays, gamma rays are packets of energy called photons. Gamma rays are a radiation hazard for the entire body. Although gamma rays can pass completely through the human body, some energy may be absorbed by tissue.
- X-rays: X-rays are high-energy photons produced by the interaction of charged particles with matter. Literally thousands of x-ray machines are used daily in the medical and other industries for examinations, inspections, and process controls. Because of their many uses, X-rays are a major source of human-made radiation exposure.
Controlling Exposure
Basic control methods for external sources of ionizing radiation include:
- Time: Minimize exposure time to reduce the total dose.
- Distance: Maximize the distance between workers and the radiation source.
- Shielding: Minimize exposure by placing an appropriate shield between workers and the source.
Knowledge Check Choose the best answer for the question.
2-9. Which of the following describes ionizing radiation?
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