Accurate determination of radionuclidic purity and half-life of reactor produced Lu-177G for metabolic radioimmunotherapy

The accurate detn. of radionuclidic purity and half-life of the beta emitter 177gLu used for metabolic radioimmunotherapy is presented. High-resoln. gamma spectrometry, as well as deconvolution of beta decay curve measured by spectrometry with liq. scintillation counting, have been adopted for quality control of different samples available on the market. A simple method was developed to distinguish between the different methods available for prodn. of 177gLu: i.e., either direct (n,γ) reactions of enriched 176Lu or indirect (n,γ) activation of enriched 176Yb followed by β- decay. In the first case, the long-lived metastable level 177mLu is present in the radioactive prepn. and a low specific activity radionuclide is obtained, in the latter a very high purity and high specific activity 177gLu is produced