![]() ![]() a great pc game or, The half life of a radioisotope is the time taken for the. For example, Co-60 has a half-life of about 5 years while Ir-192 has a half-life of about 74 days. Back Half-Life is a revolutionary game for computer more need not be said. Although the half-life pattern is the same for every radioisotope, the length of a half-life is different. After ten half-lives, less than one-thousandth of the original activity will remain. At two half-lives, it will have an intensity of 25% of a new source. ![]() At one half-life, its intensity will be cut to 50% of the original intensity. For example, a source will have an intensity of 100% when new. The half-life of a radioisotope is the time required for one half of the amount of unstable material to degrade into a more stable material. Let define half-life (H) of a variable x as the time for the expected value of x(t) to reach the intermediate (middle) price between the current. Specifying the half life or mean life of a process is a way of quantifying how fast it is occurring, when the whole process would in principle take forever to. The decay of radioactive elements occurs at a fixed rate. The original concept of half-life probably comes from the physics: measuring the rate of decay of a particular substance, half-life is the time taken by a given amount of the substance to decay to half its mass. As more and more unstable atoms become stable atoms, less radiation is produced and eventually the material will become non-radioactive. For this reason, radioactive sources become weaker with time. However, once the atom reaches a stable configuration, no more radiation is given off. To change from an unstable atom to a completely stable atom may require several disintegration steps and radiation will be given off at each step. ![]() As a radioisotope atom decays to a more stable atom, it emits radiation only once. Nuclear medicine The length of time required for a radioisotope to decay to one-half of the original amount having the same radioactivity a radioisotope’s effective T1/2 is either the time of decay-physical T1/2-or the time to elimination from a biological system.> Radioactive Decay and Half-Life Radioactive Decay and Half-LifeĪs mentioned previously, radioactive decay is the disintegration of an unstable atom with an accompanying emission of radiation. Immunology The time an immunoglobulin stays in the circulation: 20–25 days for IgG, 6 days for IgA, 5 days for IgM, 2–8 days for IgD, 1–5 days for IgE Haematology The time that cells stay in the circulation-e.g., red blood cells, 120 days, which increases after splenectomy platelets, 4–6 days eosinophils, 3–7 hours neutrophils, 7 hours The amount of time required for a substance to be reduced to one-half of its previous level by degradation and/or decay (radioactive half-life), by catabolism (biological half-life), or by elimination from a system (e.g., serum half-life) The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. ![]()
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