Radiation Protection Dosimetry Advance Access originally published online on January 25, 2008
Radiation Protection Dosimetry 2008 130(2):149-161; doi:10.1093/rpd/ncm496
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Radon progeny microdosimetry in human and rat bronchial airways: the effect of crossfire from the alveolar region
1 Department of Materials Engineering and Physics, Division of Physics and Biophysics, University of Salzburg, A-5020 Salzburg, Austria
2 National Institute of Standards and Technology, Ionizing Radiation Division, Physics Laboratory, Gaithersburg, MD 20889, USA
3 Present address: Center of Pure and Applied Mathematics, University of California, Berkeley, CA 94720, USA
* Corresponding author: werner.hofmann{at}sbg.ac.at
Received May 23, 2007, amended November 23, 2007, accepted December 12, 2007
The objectives of the present study were (1) to present a comprehensive analysis of the microdosimetric quantities in both human and rat bronchial airways and (2) to assess the contribution of the crossfire alpha particles emitted from the alveolar region to bronchial absorbed doses. Hit frequencies, absorbed doses and critical microdosimetric quantities were calculated for basal and secretory cell nuclei located at different depths in epithelial tissue for each bronchial airway generation for defined exposure conditions. Total absorbed doses and hit frequencies were slightly higher in rat airways than in corresponding human airways. This confirms the a priori assumption in rat inhalation experiments that the rat lung is a suitable surrogate for the human lung. While the contribution of crossfire alpha particles is insignificant in the human lung, it can reach 33% in peripheral bronchiolar airways of the rat lung. The latter contribution may even further increase with increasing alveolar 214Po activities. Hence, the observed prevalence of tumors in the bronchiolar region of the rat lung may partly be attributed to the high-linear energy transfer crossfire alpha particles.