Microdosimetry of inhomogeneous radon progeny distributions in bronchial airways.
A Monte Carlo code, initially developed for the calculation of microdosimetric spectra for alpha particles in cylindrical airways, has been extended to allow the computation (i) of additional microdosimetric parameters and (ii) for realistic exposure conditions in human bronchial airways with respect to surface activity distribution and airway geometry. The objective of the present study was to investigate the effects of non-uniform distributions of radon progeny activities in bronchial airways on cellular energy deposition parameters. Significant variations of hit frequencies, doses and microscopic energy deposition patterns were observed for epithelial cell nuclei, depending strongly on the assumed activity distributions. Thus, epithelial cells located at different positions in a given bronchial airway may experience a wide range of biological responses. The results obtained suggest that the hit frequency may be the primary physical parameter for alpha particles, supplemented by microdosimetric single event spectra, to be related to biological effects for chronic low level exposures.
Fakir
H
H
Institut de Radioprotection et de Sûreté Nucléaire, DRPH/SDI, B.P. no. 17, F-92262 Fontenay-aux-Roses Cedex, France. hatim.fakir@sbg.ac.at
Hofmann
W
W
Caswell
R S
RS
Aubineau-Lanièce
I
I
D000280:Administration, Inhalation; D000396:Air Pollutants, Radioactive / Q000032:analysis / Q000493:pharmacokinetics; D000512:Alpha Particles; D016880:Anisotropy; D001822:Body Burden; D001980:Bronchi / Q000378:metabolism*; D003198:Computer Simulation; D006801:Humans; D018499:Linear Energy Transfer / Q000502:physiology; D008954:Models, Biological; D017711:Nonlinear Dynamics; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011874:Radiometry / Q000379:methods*; D017687:Radon Daughters / Q000008:administration & dosage / Q000032:analysis* / Q000493:pharmacokinetics*; D012062:Relative Biological Effectiveness; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D014018:Tissue Distribution
D000396:Air Pollutants, Radioactive; D017687:Radon Daughters