RESUMEN
The consistency of the published values for fission averaged cross-sections of threshold reactions induced in a nuclear reactor is analyzed. The influence of the literature data involved in the determination of these cross-sections is discussed. Renormalizations based on cross-sections value for the standard reactions, isotopic abundances of the precursors and radiation emission probabilities of the radionuclide under study and the monitor, are applied to the evaluation of the cross-sections for the reactions: (46)Ti(n,p)(46)Sc; (47)Ti(n,p)(47)Sc; (48)Ti(n,p)(48)Sc; and (64)Zn(n,p)(64)Cu.
Asunto(s)
Radioisótopos de Cobre/química , Neutrones , Fisión Nuclear , Radiometría/métodos , Escandio/química , Titanio/química , Radioisótopos de Zinc/química , Radioisótopos de Cobre/efectos de la radiación , Isótopos/química , Isótopos/efectos de la radiación , Dosis de Radiación , Escandio/efectos de la radiación , Titanio/efectos de la radiación , Radioisótopos de Zinc/efectos de la radiaciónRESUMEN
In this study, production of Gallium-66 by irradiation of natural zinc target with 15 MeV protons was verified.Gallium-66 is an intermediate-lived radioisotope that has potential for positron emission tomography (PET), along study of the biological processes with intermediate to slow target tissue uptake. 66Ga [t1/2 = 9.49 h; ß+ (56.5 percent), EC(43.5 percent)] can be used in a large number of labeled proteins, peptides, and small molecules. We have produced 66Ga by irradiation of natural Zinc with 15 MeV proton beam, using the cyclotron -30Cyclon- at nuclear research center for agriculture and medicine. A 400µm Zinc target with copper backing substrate was irradiated for 1.5 hours with total integrated current 250µAh. Gallium has been purified from irradiated targets by passing through the cation exchange column and diisopropyl ether extraction. The concentration of zinc and copper in 0.1 and 0.5 ppm were respectively measured by polarography. In order to detect impurities, gallium radioisotopes were detected by a Canberra HPGe gamma spectrometer. The production yield at EOB was 7mCi/µAh with total activity of 1.75 Ci for Gallium-66. The ratio of activity at 9 hours after the EOB for 66Ga(t 1/2=9.5h), 68Ga(t1/2=1.1h) and 67Ga(t1/2=78h) was 98.63 percent, 1.12 percent and 0.25 percent respectively. The amount of 64Ga(t1/2=0.04h), and 70Ga(t1/2=0.35h) was not detectable. Due to using natural zinc, this method could be considered as an inexpensive method for laboratories studies. The production process comparing the irradiation of natural copper has no impurity such as copper-61, 64 and 67. The purification including cation-exchange and ether extraction afforded high yield beside negligible concentrations of copper and stable zinc as chemical impurity.
Asunto(s)
Zinc/química , Radiofármacos/química , Radioisótopos de Galio/química , Tomografía Computarizada de Emisión , Ciclotrones , Cobre/química , Fuentes de Radiación , Radiofármacos , Fisión NuclearRESUMEN
Groups of animals (Wistar rats) were fed with rations doped with uranyl nitrate at concentrations ranging from 0.5 to 100 ppm. The uranium content in the ashes of the organs was measured by the neutron-fission track counting technique. The most striking result is that the transfer coefficients, as a function of the uranium concentration, exhibit a concave shape with a minimum around 20 ppm-U for all organs. Explanations to interpret this finding are tentatively given.