Evaluation of the Clearance of Particles Deposited on the Conducting Airways of Beagle Dogs

ABSTRACT The new respiratory tract dosimetry model of the International Commission on Radiological Protection incorporates long-term retention of radioactive particles in conducting airways in its radiation dosimetry calculations. Values for long-term retention must be realistic to gain acceptance of the model and allow meaningful airway calculations. In the present study, Beagle dogs were used to evaluate particle clearance and determine if particles were retained in conducting airways of the lung. After anesthesia, a fiberoptic bronchoscope was used to position a microspray nozzle in specific airways having internal diameters of about 4,8, and 15 mm. The dogs were made temporarily apneic, and the dosing volume was expelled through the microspray nozzle using 1 ml of air. In the clearance experiments, dogs were administered either about 8 × 106 radiolabeled 3–4 μm polystyrene latex microspheres or 3 × 105 radiolabeled 1.5-μm fused aluminosilicate particles in 20-μl of saline suspension. External counting...