RESUMO
PURPOSE: The primary objective of this paper was to investigate the distribution of radiation doses and the related biological responses in cells of a central airway bifurcation of the human lung of a hypothetical worker of the New Mexico uranium mines during approximately 12 hours of exposure to short-lived radon progenies. MATERIALS AND METHODS: State-of-the-art computational modelling techniques were applied to simulate the relevant biophysical and biological processes in a central human airway bifurcation. RESULTS: The non-uniform deposition pattern of inhaled radon daughters caused a non-uniform distribution of energy deposition among cells, and of related cell inactivation and cell transformation probabilities. When damage propagation via bystander signalling was assessed, it produced more cell killing and cell transformation events than did direct effects. If bystander signalling was considered, variations of the average probabilities of cell killing and cell transformation were supra-linear over time. CONCLUSIONS: Our results are very sensitive to the radiobiological parameters, derived from in vitro experiments (e.g., range of bystander signalling), applied in this work and suggest that these parameters may not be directly applicable to realistic three-dimensional (3D) epithelium models.
Assuntos
Brônquios/efeitos da radiação , Modelos Biológicos , Radônio/efeitos adversos , Poluentes Ocupacionais do Ar/efeitos adversos , Algoritmos , Fenômenos Biofísicos , Brônquios/anatomia & histologia , Efeito Espectador , Simulação por Computador , Humanos , Hidrodinâmica , Imageamento Tridimensional , Mineração , Modelos Anatômicos , Método de Monte Carlo , New Mexico , Exposição Ocupacional , Material Particulado/efeitos adversos , Produtos de Decaimento de Radônio/efeitos adversos , UrânioRESUMO
During the last decade, computational fluid dynamics techniques proved to be a powerful tool in the modelling of biological processes and the design of biomedical devices. In this work, a computational fluid dynamics method was applied to model the transport of inhaled air and radioactive particles within the human respiratory tract. A finite volume numerical approach was used to compute the flow field characteristics and particle trajectories in the lumen of the first five airway generations of the human tracheobronchial tree, leading to the right upper lobe. The computations were performed for breathing and exposure conditions characteristic of uranium mines and homes. Primary radon daughter deposition patterns and energy distributions were computed, exhibiting highly inhomogeneous particle and energy deposition patterns. The results of the present modelling effort can serve as input data in lung cancer risk analysis.