![]() Neutrons are, as the name implies, neutral in their charge. Neutron - A small atomic particle possessing no electrical charge typically found within an atom’s nucleus. Isotope - A nuclide of an element having the same number of protons but a different number of neutrons. Gamma rays penetrate tissue farther than do beta or alpha particles, but leave a lower concentration of ions in their path to potentially cause cell damage. All gamma rays emitted from a given isotope have the same energy, a characteristic that enables scientists to identify which gamma emitters are present in a sample. These rays have high energy and a short wave length. Gamma Rays - High-energy electromagnetic radiation emitted by certain radionuclides when their nuclei transition from a higher to a lower energy state. See also alpha particle, gamma ray, neutron, x-ray.ĭecay Chain (Decay Series) - The series of decays that certain radioisotopes go through before reaching a stable form. They also pose a serious internal radiation threat if beta-emitting atoms are ingested or inhaled. They can pose a serious direct or external radiation threat and can be lethal depending on the amount received. Although they can be stopped by a thin sheet of aluminum, beta particles can penetrate the dead skin layer, potentially causing burns. See also beta particle, gamma ray, neutron, x-ray.Ītom - The smallest particle of an element that can enter into a chemical reaction.īeta Particles - Electrons ejected from the nucleus of a decaying atom. When alpha-emitting atoms are inhaled or swallowed, however, they are especially damaging because they transfer relatively large amounts of ionizing energy to living cells. Therefore, they do not damage living tissue when outside the body. ![]() Alpha particles can be stopped by a thin layer of light material, such as a sheet of paper, and cannot penetrate the outer, dead layer of skin. Alpha particles generally carry more energy than gamma or beta particles, and deposit that energy very quickly while passing through tissue. Certain radioactive nuclei emit alpha particles. If you take a soil sample anywhere in the world, including your backyard, you will find uranium atoms that date back to when the Earth was formed.Īlpha particles - The nucleus of a helium atom, made up of two neutrons and two protons with a charge of +2.Naturally occurring uranium-238 present in the Earth’s crust has a half-life of almost 4.5 billion years.Uranium is a radionuclide that has an extremely long half-life. After 24 hours, the radioactivity from the procedure will be reduced by more than 90%. The short half-life of technetium-99m helps keep the dose to the patient low.For example, technetium-99m, one of the most common medical isotopes used for imaging studies, has a half-life of 6 hours. ![]() Radionuclides used in nuclear medicine procedures, have short half-lives. A good rule of thumb is that, after seven half-lives, you will have less than one percent of the original amount of radiation.Ĭlick here for a closer look at half life.ĭepending on the radionuclide, this process could be fast or take a very long time – radioactive half-lives can range from milliseconds to hours, days, sometimes millions of years. Half-life is the length of time it takes for half of the radioactive atoms of a specific radionuclide to decay. ![]() Another feature of each radionuclide is its half-life.
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