ИСТИНА

Improved centrifugal extraction at semi-countercurrent generator designed for both technetium-99m and technetium-99 preparation is presented in this study. The main source of medical technetium in the generator is 99Mo - which could be: 1) a product of uranium fission, 2) the result of 98Mo irradiation with neutrons or 3) a product of special target bombardment at particle accelerators. The chemical processing method applied extraction from methylethylketone (MEK) as described in [1]. It provides the preparation of high-purity technetium; the solution of technetium-99m with adjustable and high volumetric activity. No losses of molybdenum occur, which is critically important while the work is done with enriched molybdenum-98. Mo-99 with a wide range of specific activity could be operated. The developed semi-current generator has a high mechanical reliability in operation according to the absence of rubbing points: contact between the rotating drum and the fixed parts (tubes, mixers), and the certified time of this operation is limited only by the engine resource. Radiation doses from 99Mo and 99mTc have practically no effect on the engine operation. The main advantage of the generator is the possibility of highly efficient separation of isotopes of molybdenum and technetium, obtained using both enriched and naturally stable isotopes, as well as any irradiation facilities (reactors, accelerators) to produce a product - potassium pertechnetate solution with the required volumetric activity and radiochemical purity. The basic parameters of the 99mTc generator are listed below: • the summary activity of the initial 99Mo - 99mTc mixture may be approximately 30 Curie; • the 99mTc extract separation takes about 6-8 min; • the final product yield amounts to not less than 90%; • the radiochemical purity is up to 99%; • the extract volume is not more than 50 cm3; • the 99Mo content in the final product does not exceed 10-5 %. • the concentration of MEK in the solution of 99mTc is not more than 0,04[mg]/[ml]. • pH of the 99mTc aqueous solution is within the range of 6.0-7.0 • total time of receipt of the final product is less than 1,5 hours. In the last decade, a number of alternative (nuclear-reactor-free) methods for medicine-intended 99mTc isotope production were actively developed using charged particle accelerators in particular. The technology of 99mTc production applied centrifugal extraction stationary generator upon the irradiated and alkali dissolved molybdenum target is created and developed in the department of isotopes investigation and production at the A.Alikhanyan National Science Laboratory, AANL (YerevanPhysics Institute, Armenia). A technology has been developed in which, after dissolution of an irradiated molybdenum target in alkali, technetium-99m is released on an extraction centrifugal generator created at the Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences (IPCE RAS). In case of irradiation of the target by a cyclotron proton beam the irradiation time being 3 hours the costs of the final 99mTc is minimized/ It makes possible to supply the clinics daily with this isotope of the required activity. The quality of 99mTc, which obtained by an extraction generator, is not worse and the cost of the product is lower than those of the similar solutions obtained using the sorption technology. In the test, a model solution was used, with a volume of 200 ml, containing 8.8 mg of sodium molybdate, 7.6 mg of potassium pertechnetate in 2.5 molar KOH and K2CO3.