Alpha hit frequency due to radon decay products in human lung cells.

PURPOSE To calculate the hit probabilities by alpha-particles emitted by radon progeny for basal and secretory cell nuclei in the epithelium of the human tracheobronchial tree. MATERIALS AND METHODS The equilibrium activities on the surface of airway tubes were calculated using the ICRP66 model. The stopping-power and ranges of alpha-particles in tissue were adopted from ICRU49. A semi-analytical method for determining the alpha-particle fluence rate in tissue was applied. The distributions of secretory and basal cells throughout the tracheobronchial tree were as given by Mercer et al. (1991). RESULTS The probability to hit basal cell nuclei is three-to-four times smaller than for secretory cell nuclei in the bronchial region (BB). However, the total number of traversed basal cell nuclei is greater because of the larger volume abundance of basal cells in BB. The total number of secretory cell nuclei hit in the bronchiolar region (bb) is larger than that in BB because the volume abundance of secretory cells in bb is larger than that in BB. CONCLUSIONS Basal cells are more sensitive to alpha-radiation than secretory cells. This finding is based on the analysis of the relative number of cell hits and the relative frequencies of lung cancer induction in BB and bb.