The radionuclide 90Y was produced by the activation of yttrium nitrate in the nuclear reactor core, by the reaction 89Y (n, gamma) 90Y. The radionuclide obtained was characterized with the help of the absorption curve, decay curve and beta - and gamma - ray spectra. A slight admixture cf 89Sr was observed. The organ distribution of the radionuclide produced in tumor-bearing nude mice was established on the basis of measuring ashed tissues, since fresh as well as dried tissues exerted remarkable self-absorption effects. No selective accumulation of the radioyttrium in the tumors was observed for subcutaneously located osteosarcoma and rectal carcinoma. The highest concentrations were found in the lungs, spleen and liver. Thus, our study based on the use of the radioactive tracer 90Y does not support a recommendation to use yttrium ions as a tumor localizer, which was formerly proposed on the basis of the PIXE technique.

Institute of Biophysics 1st Medical Faculty Charles University Prague