Impurities of 99mTc-generators.

The impurities present after use in 99Mo- 99mTc-generators produced by four different manufacturers were investigated by means of the energy spectrum and half-life measurements. The generators produced with fission contained only a few impurities, and the half-lives of their nuclides were relatively short. The only generator manufactured using neutron bombardment contained several nuclides whose half-lives were in a range of a few months, but also a 60Co nuclide whose long half-life may give rise to difficulties in destroying the generator.