Deposition of 0.1 μm aggregate and spherical 67Ga2O3 particles inhaled by Beagle dogs

Respiratory tract deposition of inhaled 67Ga2O3 particles, aggregate and spherical, was studied in a group of 10 Beagle dogs following nose-only inhalation exposures. Activity median diameter for the aggregate and spherical particles, as measured by a diffusion battery, were 0.07 +- 0.01 μm (mean +- SD) with a geometric standard deviation (sigma g) of 1.6, and 0.12 +- 0.03 μm (sigma g = 1.8), respectively. Whole-body counting and gamma camera imaging techniques were used to determine deposition as a percentage of the inhaled particles. Values for the aggregate and spherical particles were, respectively: total respiratory tract, 39 +- 19 percent and 42 +- 17 percent; pulmonary, 25 +- 12 percent and 29 +- 11 percent. This similarity in deposition patterns shows that data from ultrafine aggregate particles can be generalized to small spherical particles when diffusion diameter is used to characterize particle size