223Ra for endoradiotherapeutic applications prepared from an immobilized227Ac/227Th source

Abstract

A method is described for the production of223Ra (t1/2=11.4 d) in a quality useful for endoradiotherapeutic applications. The method is based on a long term operating generator with a source of227Ac (t1/2=21.7 years), from which223Ra is eluted. The227Ac was isolated from a231Pa source using the f-element selective extraction chromatographic material TRU-resin. The purified227Ac/227Th source was subsequently applied to another extraction chromatographic resin, containing the extractant P,P′-di(2-ethylhexyl)methanediphosphonic acid on silica (Dipex-2) and used as a generator for223Ra. From the generator column, the yield of223Ra was about 60 kBq per 100 kBq of227Ac with a highly effective separation of223Ra from the precursors. In production runs, the activity of227Ac was found to be 6×10-6relative to the eluted activity of223Ra. By using a second column of Dipex-2 for additional purification, the activity of Ac was reduced to below 7×10-8relative to223Ra with nearly quantitative recovery of223Ra. The described procedure resulted in a high purity223Ra preparation, potentially useful in,e.g., targeted radiotherapy of tumors.