Cyclotron Produced Radioisotopes 97Ru, 178W/178Ta
Development of Methods of the Radioisotope Production of the Cyclotron Type (97Ru and Generator 178W/178Ta) for Medical Purposes
Tech Area / Field
3 Approved without Funding
Joint Institute of Nuclear Research, Russia, Moscow reg., Dubna
- NPO Soyuz (2), Russia, Moscow reg., Dzerzhinsky\nAssociation of Medical Physicists of Russia (AMFR), Russia, Moscow
Project summaryAt Present, radionuclide diagnostics allowing to research conditions of internal organs and system of human being without desturbing of integrity of his organism, is one of the most physiological methods of medical diagnostics researches.
The objective of this project is to develop methods of production of radioisotopes of cyclotron type (97Ru, 178W / 178Та) for medical purposes.
Technical approach of this project is to develop technological methods of the one-stage extraction of radionuclide - pure 97Ru and 178W from proton irradiated targets made of metallic Те and Та, respectively.
- worked out effective technologies of industrial production of 97Ru and 178W;
- developed and offered to the Ministry of Public Health of Russia and to the Ministry of Education of Russia proposals on development on the base of 97Ru and 178W radiopharmaceuticals and carried out their clinical examination;
- achieved necessary activity of Ru and made from 3 to 5 generators of 178Та on the base of 178W to conduct development of radiopharmaceuticals.
The scientific and commercial significance of this project is that it offers to medicine new radionuclides having a number of unique properties. Great interest to this work has been expressed by scientific centers as: Scientific Labotatories: PSI (Switzerland), Karlsrue (Germany), Triumph (Canada): for example: a) Ru: Rh(p,2p5n)Ru L.Mausner (Brookhaven National Laboratory Upton NY11973 USA; b) W: R.D.Neirmcx, M.A.Davis, B.L.Holman (Joint Program in Nuclear Medicine, Department of Radiologi, Harvard Medical School, Boston, Massachusetts, Massachusetts General Hospital, Boston, MA 02114, USA); J.L.Lacy, A.D.LeBlanc, J.W.Babid, M.W.Bungo (NASA - Johnson Space Center and Baylor College of Medicine Houston, Texas, and Duke University Medical Center, Durham, North Carolina, USA), "AMERSHAM" firm, which is one of monopolies controlling market of medical radionuclides.
Originality of the project with respect to other studies is due to the fact, that this project proposes the method of one-stage extraction of radionuclide-pure 97Ru from the Tc-target and 178W from the Ta-target, which is different from the existing at present methods, in particular for 178W, including several stages (target dissolving in a mixture of acids, multiple evaporation of the solution in order to remove traces of the nitric and fluoric acids, ion-exchange purification from possible impurities).
We have already performed a number of investigations on project. Preliminary results was published in following papers:
- Exitation and Yield for Ru Production in 99Tc(p, 3n)97Ru Reaction in 20-100 MeV Proton Energy Range. Radiochemica Acta 1992, 56, p.59.
- Metal Technetium Target and Target Chemistry for Production of Ru via the 99Tc(p,3n)97Ru Reaction. Applied Radiation and Isotopes 1996, 47(2), p. 145
- Excitation Function for W Production in the181Ta(p,4n)178W Reaction over Proton Energy Range 28.8-71.8 MeV. Radiochimica Acta 1994, 64(1), p.l
In the medical diagnostic practice, the radionuclides generated by the activation in nuclear reactor and by the processing a fission products of nuclear fuel have received wide acceptance It is save to say that by now these ways of obtaining of radionuclides for medical purpose are practically used, although necessity of radionuclides with new characteristics still is.
In connection with this, the intensive device of generated by accelerator methods of production neutron-deficit radionuclides in large quantities. The promising isotopes are primarily 97Ru and 178Та, generated in generators from the decay of living longer 178W.
To solve the problem of a large - scale production of 97Ru (curies) after the irradiation -is possible, in our opinion, if the proton target is made of technetium-99. Only in this case 97Ru will be radioisotopically pure. Metallic technetium is a very good material for cyclotron targets with a heat release more than 3 kW/g. At present application of the "Tc as a target material is possibly limited by the fact that 99Tc is considered as an exotic and radioactive metal. With respect to 99Tc targets for proton irradiation these factors can hardly be considered as restrictive. In addition, the following 99Tc should be taken into account:
- First 99Tc concentration in the used fuel of nuclear power stations with amounts up to 1 kg per 1 ton of nuclear fuel;
- Second, 99Tc belongs to isotopes with low radio toxic (group B), that allows one to work with metallic 99Tc as a closed radioactive source;
- Third, technological processes of the metallic 99Tc production in sufficient quantities (~ kilograms) have been developed in Russia.
For this purpose it is nessary to invent:
- methods of work with metallic 99Tc in proton beams with the energy up to 50 MeV;
- methods of onestage distillation extraction of 97Ru ffrom the 99Tc target after get after irradiation.
One of the problems of an inexpensive 178W / 178Ta production is its extraction from the proton-irradiated tantalum. It is proposed for this purpose to study a one stage method of extraction of 178W from metallic Та using the gas thermochromatography (GTC), namely, determination of optimal GTC parameters for achieving the radionuclide yield of more than 90 % during the burning ~ 10 g of metallic Та in the humid oxygen.
Thus, the main purpose of this project is to develop technological methods of the one-stage extraction of radionuclide - pure 97Ru and 178W from proton irradiated targets made of metallic Те and Та, respectively.
The success of this project depends on the efficiency of technological methods of 97Ru and 178W extraction, which is estimated on their parameters like the yield of the desirable nuclides, their radionuclide and radioisotope purity, duration and complexity of the technological process, amount of radioactive wastes.