Separation of Lanthanides

About

Radiopharmaceutical compounds, such as Samarium-153 ethylenediamine tetramethylene phosphonate, are important therapeutics approved in the United States and Europe. Many therapeutic materials like Sm-153 are not optimal in therapy due to the presence of other isotopes and chemical impurities that compete for labeling sites on the targeting agent, or due to the low specific activity of the radioisotope requiring increasing the dose of the targeting agent, potentially to the point of toxicity for the patient. Isotopes destined for medical applications often possess short half-lives, typically a few days for lanthanides. A short half-life requires an efficient pipeline from isotope creation to dose administration to enhance the radiation dose delivered to the target cells while limiting patient exposure. In these applications, a chemically pure material possessing the highest possible concentration of the required radioisotope is desired. Researchers at the University of Missouri invented a hot-cavity surface ionization source made from titanium that efficiently ionizes lanthanides for electromagnetic separation with an end goal of specific activity on the order of 50-250 mCi. This source would be suitable for conducting pre-clinical or clinical trials in the development of radiopharmaceuticals and could lead to the construction of production scale facilities. Since neutron capture on titanium only sources produces short-lived isotopes, it would be possible to load lanthanide samples into the source prior to irradiation. The titanium source could then be removed from the reactor already loaded with an activated lanthanide and quickly installed into the electromagnetic isotope separator, saving valuable time and operator dose, and requiring less heat shielding due to lower temperatures involved in volatilizing and ionizing the lanthanides.