ABSTRACT
INTRODUCTION: Thermal neutron activation of 152Sm [152Sm(n,γ)153Sm] using natural or isotopically enriched (by 152Sm) samarium target is the established route for production of 153Sm used for preparation of 153Sm-EDTMP for pain palliation in cancer patients with disseminated bone metastases. However, some long-lived radionuclidic contaminants of Eu, such as, 154Eu (t½=8.6y) are also produced during the target activation process. This leads to detectable amount of Eu radionuclidic contaminants in patients' skeleton even years after administration with therapeutic doses of 153Sm-EDTMP. Further, the presence of such contaminants in 153Sm raises concerns related to radioactive waste management. The aim of the present study was to develop and demonstrate a viable method for large-scale purification of 153Sm from radionuclidic contaminants of Eu. METHODS: A radiochemical separation procedure adopting electroamalgamation approach has been critically evaluated. The influence of different experimental parameters for the quantitative removal radionuclidic contaminants of Eu from 153Sm was investigated and optimized. The effectiveness of the method was demonstrated by purification of ~37 GBq of 153Sm in several batches. As a proof of concept, 153Sm-EDTMP was administered in normal Wistar rats and ex vivo γ-spectrometry of bone samples were carried out. RESULTS: After carrying out the electrolysis under the optimized conditions, the radionuclidic contaminants of Eu could not be detected in purified 153Sm solution by γ-spectrometry. The overall yield of 153Sm obtained after the purification process was >85%. The reliability of this approach was amply demonstrated in several batches, wherein the performance remained consistent. Ex vivo γ-spectrometry of bone samples of Wistar rats administered with 153Sm-EDTMP (prepared using electrochemically purified 153Sm) did not show photo peaks corresponding to radionuclidic contaminants of Eu. CONCLUSIONS: A viable electrochemical strategy for the large-scale purification of 153Sm from radionuclidic contaminants of Eu has been successfully developed and demonstrated.
