Characteristics of tantalum dust and dust generator for bronchography.

The two tantalum powders, "5mu" and "1.4mu", available from Fansteel Metals, are characterized with respect to particle size. Results show that these powders cannot be used directly for tantalum bronchography, but require fractionation to achieve a range of sizes for effective use in tantalum bronchography. This task can be accomplished with the BAHCO Micro Particle Classifier. The powder designated "1.4mu" is superior to the "5mu" powder because about 60% by weight can be salvaged by separation for use in bronchography, compared to only 7% by weight of the "5mu" powder. Theoretical considerations of particle deposition in the human respiratory tract indicate that the material obtained with throttle 16 of the BAHCO is best suited for tantalum bronchography. The dust generator is a good tool to deliver a dust cloud into the lung. The generator can operate for approximately 2 1/2 hours before the brush of the brush feed must be replaced; a procedure taking about 10 min. Additional maintenance is unnecessary. The breathing resistance of 1.1 inch of water imposed by the generator system, and which has to be overcome by the patient, is judged acceptable. The bronchograms obtained by introducing tantalum dust for 10 min into an artificially ventilated dog lung were clear, with deposition heaviest at bifurcations. These results suggest that the generator should now be used for human bronchography.