TECHNETIUM (Technetium, Tc) — chemical element VII of Mendeleyev's group; sequence number 43, at. weight (weight) 98,9062; the artificial radioelement which does not have stable isotopes. 21 radioisotopes T are known. with mass numbers from 90 to 110 and 9 isomers with half-lives of 0,82 sec. to 4,2*10 6 years (see. Isotopes ). Metal T. in the form of powder has gray color, compact metal (ingots of melted metal, a wire, etc.) — silver-gray, t°pl 2200 ° ± 50 °, t°kip 4700 °. Existence of an element and its main chemical properties were predicted by D. I. Mendeleyev, the Crimea it was called as an analog of manganese ekamarganets. It is open in 1937 by ital. scientists Perrye and Segre (S. for Perrier, E. Segre) during the bombing of kernels of molybdenum deuterons and received the name «technetium» (Greek technitos artificial).
In medicine apply 99m Tc which is an affiliated product 99 Mo and breaking up with half-life 6,007 hours by isomeric transition with emission of gamma quanta (Egamma = 140,5 kev, an exit — 88,3%), characteristic x-ray emission, electrons of conversion and Auger of electrons. As a result of disintegration 99m Tc passes into 99 CU, to-ry, in turn, undergoing a beta decay, turns in stable 99Ru. Half-life 99 CU — 2,12*10 3 years. To use 99m Tc for radio-isotope diagnosis offered in 1962 Mr. P. V. Harper and soavt.
In a crust, time are developed and are used in a wedge, practice apprx. 20 various radio pharmaceuticals (see) on a basis 99m Tc. They are applied to a functional and anatomo-topographical research of a brain, thyroid and sialadens, lungs, a liver, kidneys, a skeleton, cardiovascular, zhelchevydelitelny and limf, systems, marrow (see. Radio isotope diagnosis , Radio isotope research ).
Work with 99m Tc shall be carried out according to the existing «Ground health regulations of work with radioactive materials and other sources of ionizing radiation». 99m Tc concerns to group of radiation hazard of. The greatest activity 99m Tc in open form in a workplace which is not demanding registration or permission of bodies state a dignity. supervision — 100 mkkyur (3,7 kBq).
Bibliography: Parker R., Smith P. and Taylor D. Bases of a nuclear medicine, the lane with English, M., 1981; With p and - c and V. I. and Kuzin A. N. F-Technetium, M., 1981, bibliogr.; Dillman L. T. Radionuclide decay, schemes and nuclear parameters for use in radiation-dose estimation, J. nucl. Med., v. 10, suppl. 2, p. 1, 1969; Table of isotopes, ed. by C. M. Lederer a. V. S. Shirley, N. Y., a. o., 1978.
H. F. Tarasov.