Ruthenium Radioisotopes as Contaminants in Eluates from 99Mo-99mTc Generators

The measurement of the ¹⁰⁶Ru content in ^99mTc eluates from ⁹⁹Mo-^99mTc generators is difficult because of the proximity of the ¹⁰³Ru and ¹⁰⁶Ru gamma-ray spectral peaks and the low ¹⁰⁶Ru content. ¹⁰⁶Ru causes a relatively high whole-body dose, similarly as known contaminants ⁶⁰Co, ¹³⁴Cs, ¹⁴⁰Ba and some others. Assuming that ruthenium is eliminated from the body with the biological half-life 7.3 days (according to ICRP) the additional absorbed dose caused by ¹⁰⁶Ru does not exceed, with regard to the low content of this nuclide, the dose due to ¹⁰³Ru. The results are given of the preliminary experiment in animals with the aim to determine the biological behaviour of ruthenium radioisotopes after the administration of the ^99mTc eluate containing these contaminants.