Radiation decomposition of technetium-99m radiopharmaceuticals.

Technetium-99m radiopharmaceuticals are shown to be subject to autoradiation-induced decomposition, which results in increasing abundance of pertechnetate in the preparation. This autodecomposition is catalyzed by the presence of oxygen, although the removal of oxygen does not prevent its occurrence. The initial appearance of pretechnetate in the radiopharmaceutical is shown to be a function of the amount of radioactivity, the quantity of stannous ion used, and the ratio of Tc-99m to total technetium in the preparation.