Clinical studies have indicated that carinal regions of the airway generation 3–5 are preferential sites of tumor development following inhalation of radon progenies. These coincide with the locations where primary hot spots of deposition have been found. However, current lung dosimetry models do not take into consideration the inhomogeneity of deposition within the airways. In this study, computed local distributions of deposited inhaled radionuclides, such as radon progenies in morphologically realistic human airway bifurcation models, are analyzed for different flow rates and particle sizes. Then, local deposition enhancement factors (EF), defined as the ratio of local to average deposition densities, are computed by scanning along the surface of the bifurcation with prespecified surface area elements. The computed enhancement factors indicate that cells located at carinal ridges may receive localized doses, which are two orders of magnitude higher than the average values. Here, the probability of multiple hits can be quite high even at low doses. If the number of multiple cellular hits plays a crucial role in lung cancer development, then the maximum enhancement factor could serve as a useful parameter for a mechanism-based risk analysis of inhaled radionuclides.
- Bronchial carcinoma
- Deposition enhancement factors
- Radon inhalation
ASJC Scopus subject areas