Lobar deposition and retention of relatively insoluble particles in beagle dogs

The relative distributions of lung lobar weights and radioactivity associated with insoluble particles have been determined as a function of time after inhalation exposure in Beagle dogs. Different radioactivity/lung weight ratios observed in the different lobes indicated that the apical lobes had proportionately more particles deposited per lobe weight and the diaphragmatic lobes had proportionately less particles deposited per unit lobe weight than the overall ratio for the lung as a whole. These differences amounted to about +-20% and could be reflected to corresponding differences in absorbed radiation dose, particularly for beta emitters. These differences were consistent over the entire observation period (1 hour to 3 years after exposure), indicating that the clearance processes for insoluble materials were equally effective in all lobes