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Скачать бесплатно! Научная работа на тему MOLYBDENUM WILL HELP DIAGNOSE CANCER. Аудитория: ученые, педагоги, деятели науки, работники образования, студенты (18-50). Minsk, Belarus. Research paper. Agreement.

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Опубликовано в библиотеке: 2021-09-29
Источник: Science in Russia, №1, 2012, C.20-22

The town of Melekes (Dimitrovgrad since 1972) in the Ulyanovsk region started intensely developing due to the construction of the Institute of Atomic Reactors in 1956. The Institute was created on the initiative of Academician Igor Kurchatov*--our country needed a center for atomic energy engineering and research.


Today there are six experimental reactors here, including SM high flow research reactor, launched in 1961. The design of its active zone is unique--a little bit over 50 1 with the so-called water trap, providing an unprecedented high density neutron flow. The heat power of the device is 100 MW, that is, 2 MW/liter, which is very high. In order to reduce the temperature, the water is pumped through heat-releasing blocks at a velocity of 13 m/s (about 2,500 tons/hour). The pressure in the case is 50 Atm. The life span of a free neutron was first determined on this reactor. In addition, the SM active zone allows the most sophisticated experiments in materials science, technological trials, etc. Fine regulation of the neutron flow allows the production of rather exotic substances. For example, Curium-248 isotope: targets from this material were used in 2000 at the Joint Institute for Nuclear Research in Dubna** in experiments aimed to get the 116th element of Mendeleyev's Table.


Not long ago a new task was found for research devices in Dimitrovgrad. A large-scale project in the sphere of nuclear medicine is now being realized in the Ulyanovsk region: industrial production of short-living isotopes for manufacture of pharmacological preparations, primarily, molybdenum-99 isotope. The Federal Center of Medical Radiology will be constructed near the Institute. It is intended to accept up to 40,000 patients annually (similar centers will be created at the leading nuclear research centers in Tomsk and Obninsk).


But why has molybdenum-99 attracted the attention of scientists? We cannot answer this question without resorting to statistics. According to the data of the Ministry of Health and Social Development of the Russian Federation, the number of cancer patients in our country increased by more than 16 percent over the last decade. Mortality from various forms of cancer increased to 13.8 percent and now ranks second in population mortality causes in Russia. More than 2.5 mln patients are registered at cancer centers--1.8 percent of the population in general. More than 60 percent of primary patients are registered with disease stages III and IV--that is, when the disease is far advanced. The offered way out--early diagnostics by means of isotope products.


An obligatory condition for the development of nuclear medicine is patient's safety. This implies the use of short-living and ultrashort-living radiopharmaceuticals. That is when molybdenum-99 becomes necessary. Though it is important not in itself, but its product-- short-living technetium-99. Medicine makes use of unique characteristics of Tc-99, such as its mild effects on human organism in combination with a possibil-


See: Ye. Velikhov, "He Dreamt of a Sun on Earth", Science in Russia, No. l, 2003.--Ed.


** See: A. Sissakian, "Dubna's Worldwide Glory", Science in Russia, No. 2, 2006.--Ed.

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ity to diagnose a disease at the earliest stages. According to the data of the World Nuclear Association, up to 30 mln diagnostic procedures are carried out annually with the use of Tc-99 all over the world.


Russia is a world producer of isotopes. More than 70 percent of total output of stable and radioactive isotopes are exported. However, the molybdenum market was traditionally divided between Canada, European countries, and Republic of South Africa. But Canada, previously meeting up to 40 percent of world demand in this substance, recently had problems with the main producer reactor, and this niche became free. And the Rosatom State Corporation did not hesitate to occupy it for two years, which was supported by the Committee for Updating and Technological Development of Economy under the President of Russia. Industrial production of molybdenum-99 was organized at the State Scientific Center of the Research Institute of Atomic Reactors in Dimitrovgrad within the framework of the National Program for Nuclear Medicine. Vladimir Troyanov, Head of the Institute, said, "It is quite real that we can become the greatest producers of molybdenum in the world." The medical isotope shortage in the world market has now surpassed 30 percent, the mean weekly need in it being up to 12,000 Ci (isotope products are measured not in grams--by weight--but in material activity units--in Curies). The price of molybdenum-99 sometimes reached $1,500 per Ci.


"At our Institute this radionuclide is obtained by irradiation in a reactor of special uranium targets (by design they are usual heat-releasing installations, very small, enriched by U-235 isotope)," said Rostislav Kuznetsov, head of the Department of Radionuclide Sources and Preparations of the same Institute. "The next stage is radiochemical isolation. In the so-called hot chambers the exposed targets are dissolved in alkali--molybdenum remains in the solution, while uranium with numerous separation fragments is precipitated. The resultant molybdenum-99 naturally disintegrates and forms another radionuclide, Technetium-99 with a period of half-life of 6 h. These two substances form the so-called generator pair. These isotopes can be effectively and rapidly separated using special generators. Molybdenum-99 remains immobile in a chromatographic column, while Technetium passes into solution. This solution is used for the synthesis of radiopharmaceutical preparations. In Russia it is done directly in clinics. In Western countries there is a network of centralized nuclear pharmacies. But this is possible only if a hospital is nearby."


The first production line was launched on December 18, 2010 and the export of Mb-99 for the Canadian Company Nordion started. This first phase of the project intends to eventually produce 800 Ci weekly. The second phase, planned for 2012-2013, intends expanding the manufacture to the level of 2,500 Ci weekly--around 20 percent of the world market volume for this product.


Technetium is the most convenient label for proton emission tomography (PET). At present only 1-5 percent of the required volume of this radionuclide in the country is available for clinical diagnostics. There are only 7 appropriate centers in Russia, while according to

стр. 21


estimations of specialists, their number must be no less than 140, primarily for cancer patients. In the USA there are more than 2,000 PET centers. According to the WHO data, the survival of cancer patients 5 years after cancer diagnostics reaches 62 percent in the USA, while in Russia the figure is less than 43 percent.


Today more than 130 radiodiagnostic methods making use of the most sophisticated equipment are used all over the world. In Russia no more than 30 of them are used, and only in the leading medical research institutions. There are more than 100 departments of radionuclide diagnostics, where in vivo studies (injection of preparations directly to the patient are carried out), more than 200 laboratories for in vitro radioimmunoassay of blood specimens, and only one specialized department of radionuclide therapy. According to the international standards, every multiprofile hospital is to have diagnostic departments of this kind and all large cancer research centers should have therapeutic departments.


In order to rectify the situation, Rosatom in collaboration with the relevant departments suggests adopting a program for the development of nuclear medicine in Russia. The authors of this program claim that it will promote solution of many important problems, including improvement of the quality and availability of diagnostics of cancer and cardiovascular diseases, updating and equipment of medical institutions for effective treatment of these patients, and, the last but not the least, training of specialists.


In addition, realization of the program will lead to development of the market of radiopharmaceutical preparations in the country due to a greater volume of orders. As a result the price of these preparations will reduce.


A. Vaganov, Molybdenum for Internal Use, "Nezavisimaya Gazeta" (NG-Science), No. 10, 2011; A. Yemelyanenkov, The Healing Atom, "Rossiiskaya Gazeta", No. 5592, 2011

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() Источник: Science in Russia, №1, 2012, C.20-22

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