Production by compact cyclotron of radiochemically pure iodine-123 as iodide for synthesis of radiodiagnostic agents.

Iodine-123-labeled radiopharmaceuticals are desirable because they give a high flux of 159-keV photons and a low radiation exposure per millicurie. Procedures suited to a compact cyclotron were developed to produce 50-mCi batches of radiochemically pure iodine-123 as iodide. Iodine-123 is separated from proton-irradiated tellurium-124 by distillation. Aqueous iodide is readily obtained by reduction with thiosulfate. Anhydrous iodide is extracted from the distillate iwth methyl ethyl ketone. The procedures for isolating radiochemically pure iodide are trouble-free, convenient, and reliable. Iodine-123-labeled o-iodohippurate and 16-iodo-9-hexadecenoic acid prepared from our iodide are now being used in clinical trials.