Measurement of 186 Re, 188 Re, 189 Re Yield on 186 W Target Irradiation by 4 He, 3 He, 1 H, and 2 H
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MEASUREMENT OF 186Re, 188Re, 189Re YIELD ON 186W TARGET IRRADIATION BY 4He, 3He, 1H, AND 2H
V. A. Zagryadskii, S. T. Latushkin, K. A. Makoveeva, T. Yu. Malamut, V. I. Novikov, A. A. Ogloblin, and V. N. Unezhev
UDC 539.172.8.15
The saturation yield of the rhenium radioisotopes 186Re, 188Re, and 189Re on irradiation of a 186W target by the nuclei 4He, 3He, 1H, and 2H with energy 47, 25, 15.3, and 19 MeV, respectively, was measured by the activation method. The chosen energy of the accelerated particles made it possible to minimize the contribution of the activity of long-lived rhenium radioisotopes in the desired radionuclides. The highest yield 3240 ± 330 MBq/μA was obtained for the radioisotope 186Re in the reaction 186W(2H, 2n)186Re. The obtained yield makes it possible to plan on using in radioimmunotherapy the radionuclide 186Re produced by means of this reaction.
The present work is dedicated to the measurement of the saturation yield of the rhenium radioisotopes 186Re, 188Re, and 189Re on the irradiation in a cyclotron of a 186W target by the nuclei 4He, 3He, 1H, and 2H. The neutronic properties and capacity of rhenium to easily bind with organic molecular complexes make rhenium radioisotopes useful in medicine for the treatment of cancers, in palliative therapy for the relief of pain accompanying bone metastases, and for the treatment of chronic inflammatory joint diseases (radiosynovectomy) (Table 1). In Russia, the following radiopharmaceuticals have been developed on the basis of 188Re: Fosforen, 188Re; Geparen, 188Re; MSA, 188Re, 5–10 μm; Zoleren, 188Re; and Sinoren, 188Re. 188 Re is obtained with a 188W–188Re generator. Currently, radiopharmaceuticals with 186Re and 189Re are not being developed, but their use could increase the number of compounds available in nuclear medicine. In this connection, research on the possibilities of obtaining carrier-free rhenium radioisotopes in a cyclotron is timely. The rhenium radioisotopes 186Re, 188Re, 189Re can be obtained by irradiating a 186W target with the nuclei 4Не, 3He, 1 2 H, and H in the U-150 cyclotron at the Kurchatov Institute. On irradiation by 4He nuclei, the radioisotopes 186Re, 188Re, and 189 Re can be produced at the same time in the reactions 186W(4He, p3n)186Re, 186W(4He, pn)188Re, and 186W(4He, p)189Re; on irradiation by 3He – 186Re and 188Re in the reactions 186W(3He, p2n)186Re and 186W(3He, p)188Re; 1H and 2H – 186Re in the reactions 186W(1H, n)186Re and 186W(2H, 2n)186Re. Currently, there are no data on the experimental cross sections or yield of the indicated rhenium radioisotopes on irradiation of 186W by the nuclei 4He and 3He, and the information on the 186 W(1H, n)186Re and 186W(2H, 2n)186Re cross sections are contradictory. For example, in [1, 2] the measured maximum cross section differs by a factor of 3 for the reaction 186W(1H, n)186Re and in [3, 4] by a factor of 1.8 for 186W(2H, 2n)186Re. On this basis, and in order to obtain new nuclear data as well as more accurate information on the efficiency of the nuclear reactions leading
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