Deposition of 0.1 μm Aggregate and Near Spherical67Ga2O3Particles Inhaled by Beagle Dogs

Abstract

Respiratory tract deposition of inhaled 67Ga2O3 particles, both aggregate and near spherical, was studied in one group of 10 Beagle dogs using nose-only exposures to both aerosols. Aggregate particles were produced by vaporization of 67Ga tetramethylheptanedione followed by heat treatment at 1100°C. Near spherical particles were produced by introducing steam at an intermediate temperature (500°C) to allow solubilization of the particles in a droplet before complete oxidation and drying at 1100°C. Particle sizes were 0.10 ± 0.02 μm (σg = 1.6) and 0.11 ± 0.02 μm (σg = 1.8) activity median diffusion diameter for the aggregate and near-spherical particles, respectively. The shape factors were 1.76 and 1.01 for aggregate and near-spherical particles, respectively. Whole body counting and gamma camera imaging techniques were used to determine deposition as a percentage of the inhaled particles. Percentage deposition values for the aggregate and near-spherical particles were, respectively: total respiratory tract, 39 ± 19% and 42 ± 16%; pulmonary, 25 ± 12% and 30 ± 10%. This similarity in deposition patterns shows that deposition data from aggregate particles can be generalized to other ultrafine particles when diffusion diameter is used to characterize particle size.