Tagging of iron oxide particles with 99mTc for use in the study of deposition and clearance of inhaled particles.

This paper describes a method of tagging iron oxide aerosol particles with 99mTc. The tagging is achieved by reducing the heptavalent pertechnetate form to its reduced state using stannous chloride in a nitrogen atmosphere. Tests by ultracentrifugation and paper chromatography shown that the tagging is virtually complete. Separation of the tag from the particles in sputum is shown to be minimal. Monodisperse aerosols of the tagged particles are produced with a spinning-disk atomizer. (Deposition and clearance of the particles in the airways and lungs is easily followed by scintigraphy.) Factors affecting attachment and separation of the tag are discussed.