Task Groups of the National Council on Radiation Protection and Measurements (NCRP) and the International Commission on Radiological Protection (ICRP) have independently revised respiratory tract dosimetry models of inhaled radioactive aerosols. Both models contain modules for calculating inhaled particle deposition. In this report, the deposition of particles in the respiratory tract was calculated based on both the NCRP and the ICRP66 models, under the same particle size distribution, lung volume, and breathing conditions. The results indicate that the largest discrepancy between the two models is for ultrafine particles, where the ICRP66 model predicts a lower tracheobronchial deposition and a higher pulmonary deposition than the NCRP model. This difference is attributed to the fact that the ICRP66 model does not take into account the enhanced diffusional deposition due to the effect of the entrance configuration of a bifurcation. This may have significant implications on dose estimates of inhaled ultrafine particles, including radon and radon progeny. © 1996 Taylor & Francis Group, LLC.

A method for producing flexible silicone rubber casts of the airways of the lungs in‐situ is described. Casts are made to correspond to lung volumes occurring during normal breathing. The lung is prepared for casting by replacing the air within with CO2 followed by filling with degassed physiological saline. The saline dissolves the CO2 gas within the airways allowing for a bubble‐free finished cast. Casting compound is then slowly injected through the trachea. The saline diffuses out of the lung and passes out of the thorax through several small slits in the thoracic wall. After the injection is completed, the cast lung is allowed to cure in‐situ before it is removed and the tissue digested away. Finished casts have an overall shape corresponding closely to the shape of the thorax. Casts produced by this in‐situ method appear to have more realistic geometrical relationships than those produced from excised lungs. Copyright © 1973 Wiley‐Liss, Inc.

Stereoradiographs have been used on occasion for three-dimensional reconstruction and measurement of objects in radiology and radiotherapy. The lack of a good stereoradiographic technique has limited the uses of steroradiographic exposures. In this paper, the principle of the double-image is outlined and a method of applying this principle to stereoradiographic exposures is developed. A computer program has been developed from geometrical considerations to analyze the stereobronchogram and to calculate the dimensions of the objects in question. The applications of this technique are discussed and its use in evaluating lung casts is described.