Word: technetium
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Each of these tracers produces only a low level of radiation and has a short "half-life" (the time in which it loses half of its remaining radioactivity). Technetium 99m, a common isotope used especially for detecting brain tumors, has one of only six hours, while fluorine 18, used in bone scans, is half decayed in less than two hours. Of greater concern are the isotopes used in laboratory tests. Among them: carbon 14, with a half-life of 5,750 years. A large hospital may conduct thousands of radioactive tests and procedures daily, including those with carbon...
...lung clot was evidently a small one-only "dime-size," speculated Dr. John Lungren, the ex-President's internist. Lungren and Radiologist Earl K. Dore discovered the clot through two recently refined tests using radioactive isotopes. First they injected human albumen tagged with radioactive iodine-131 or technetium into an arm vein. The radiant particles circulated through the small blood vessels of Nixon's lungs, and a scintillation scanner took an electronic "picture" of their distribution. Nixon's scan showed a blank area on the outer side of the right lung: the clot had settled there...
Some radioactive materials used in medical diagnosis have extremely short half-lives. For example, Molybdenum-99, manufactured in the Boston area, loses half its effectiveness in 67 hours; its derivative, Technetium, has a half-life of only six hours...
Best for Brain. Dr. John Laughlin of Manhattan's Sloan-Kettering Institute reports nitrogen 13 and oxygen 15 highly effective in studying lung diseases. An entirely artificial element, technetium 99, produced by nuclear bombardment of molybdenum in a reactor, is rated by most medical centers as the best for detecting tumors of the brain. Both the gases and technetium have the advantage of short half-lives-that is, they lose half of their radioactivity in hours, or at most a few days. Thus, their radiation is so short-lived that it will not harm the patient exposed...
...long-lived radioactive substances can produce short-lived radioactive offspring. The cow consists of an open-ended test tube with various layers of alumina and specially treated glass through which the parent substance is filtered. In the case of a parent such as molybdenum-99 (half-life: 2.8 days), technetium-99m (half-life: 6 hours) is produced, and it accumulates at the bottom of the tube (the cow's udder). The milked technetium can therefore be created only moments before it is put into a patient, and the doctor can scan its internal path while it is most active...
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