Supported ionic liquid phases for extraction and separation of medical radiolanthanides - Towards purification of medical samarium-153

Radiolanthanides are gaining more importance in nuclear medicine because of their favorable decay characteristics. The emission of beta particles with energies suitable to destroy malicous tumor cells is very useful in cancer therapy, whereas the emission of gamma photons can be used for diagnostic purposes. Some radiolantanides are even able to serve both purposes concurrently (theranostics) making it possible to follow the effectiveness of the therapy in situ. Radiolanthanides have the potential to be deployed in a wide variety of applications in nuclear medicine. Because of the very similar chemical properties across the lanthanide series, different radiolanthanides can be linked to the same chelator. This makes them easily interchangeable, by which radiopharmaceuticals can be tailored to serve a specific purpose. Selecting the most proper particle emission energy for therapy is important to keep radiation damage to healthy tissue and vital organs as low as possible. This way, a high tumor-to-normal tissue absorbed dose can be assured. However, the very similar chemical properties also imply that separation of two neighboring lanthanides is very challenging, and is one of the main challenges in the production of radiolanthanides for medical applications. Radiolanthanides are most efficiently produced in a nuclear research reactor via neutron irradiation, which involves the bombardment of an enriched target with neutrons. Depending on the production strategy followed, the obtained radiolanthanide is carrier-added or non-carrier-added. The product resulting from each production pathway might require a purification step for different reasons before being used in a radiopharmaceutical. Isolation of non-carrier-added radiolanthanides from their target material results in a product with high specific activity, which is highly suitable for targeted radiotherapy. Carrier-added-produced radiolanthanides cannot be separated from their target material, and thus will have limited specific activities only. Therefore, they are not applied in targeted radiotherapy, but are found to be very suitable for bone pain palliation, radiation synovectomy and imaging. During neutron irradiation, long-lived radionuclidic impurities might be produced concurrently, impeding the medicinal use of the carrier-added radiolanthanide and limiting its shelf-life. After all, background radiation levels of the patient have to be limited, and are strictly regulated. A purification step for