Ionizing radiation is a form of energy that carries enough power to ionize atoms or molecules, a process known as ionization. It is emitted from a variety of sources, both natural and man-made. Sources of ionizing radiation include radioactive materials and radiation generating machines, such as X-ray inspection devices for luggage, mammography, and industrial devices used for scientific research and measurement. Background radiation is radiation that is always present in the environment.
Most background radiation occurs naturally from minerals in soil, water, and the human body, while a small fraction comes from artificial elements. Cosmic radiation from space also contributes to the background radiation that surrounds us. Natural background radiation levels can vary greatly from one location to another, as well as changes in the same location over time. Non-ionizing radiation sources are used and exposed to by people every day.
This form of radiation does not carry enough energy to ionize atoms or molecules. Thousands of x-ray machines are used daily in medicine for computed tomography (CT scans) to create detailed images of bones and soft tissues in the body. Medical x-rays are the largest source of exposure to man-made radiation. X-rays are also used in industry for inspections and process controls.
The five main types of ionizing radiation are alpha particles, beta particles, positrons, gamma rays, and x-rays. Alpha particles are composed of two neutrons and two protons, while beta particles are high-energy electrons emitted from the nucleus of an atom. Positrons are positively charged particles that have the same mass as electrons but opposite charge. Gamma rays are high-energy photons that can penetrate matter more deeply than other forms of radiation.
X-rays are also high-energy photons but with lower energy than gamma rays.The boundary between ionizing and non-ionizing radiation in the ultraviolet area is not clearly defined, since different molecules and atoms ionize at different energies. It is important to understand the sources and doses of radiation in order to protect oneself from its potentially harmful effects.