Simulation of the effect of mucociliary clearance on the bronchial distribution of inhaled radon progenies and related c
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ORIGINAL ARTICLE
Simulation of the effect of mucociliary clearance on the bronchial distribution of inhaled radon progenies and related cellular damage using a new deposition and clearance model for the lung Árpád Farkas1 Received: 20 April 2020 / Accepted: 17 August 2020 © The Author(s) 2020
Abstract Most of the current dosimetry models of inhaled short-lived radon decay products assume uniform activity distributions along the bronchial airways. In reality, however, both deposition and clearance patterns of inhaled radon progenies are highly inhomogeneous. Consequently, a new deposition-clearance model has been developed that accounts for such inhomogeneities and applied together with biophysical models of cell death and cell transformation. The scope of this study was to apply this model which is based on computational fluid and particle dynamics methods, in an effort to reveal the effect of mucociliary clearance on the bronchial distribution of deposited radon progenies. Furthermore, the influence of mucociliary clearance on the spatial distribution of biological damage due to alpha-decay of the deposited radon progenies was also studied. The results obtained demonstrate that both deposition and clearance of inhaled radon progenies are highly non-uniform within a human airway bifurcation unit. Due to the topology of the carinal ridge, a slow clearance zone emerged in this region, which is the location where most of the radio-aerosols deposit. In spite of the slow mucus movement in this zone, the initial degree of inhomogeneity of the activity due to the nonuniform deposition decreased by a factor of about 3 by considering the effect of mucociliary clearance. In the peak of the airway bifurcation, the computed cell death and cell transformation probabilities were lower when considering deposition and clearance simultaneously, compared to the case when only deposition was considered. However, cellular damage remained clustered. Keywords Radon inhalation · Fast clearance · Cell death · Cell transformation
Introduction Even if the macroscopic exposure level of an individual (e.g. due to radon in air) is known (ICRP 103 2007), the resulting dose distribution within the human body is difficult to quantify because technical and ethical barriers hamper its measurement. In contrast, numerical modelling can be an effective method to quantify the radiation dose at various levels of biological organization (whole body, organs, tissues, cells, subcellular entities). This kind of approach may be feasible especially when the distribution of the energy deposition due to ionising radiation is uneven, like in the case of * Árpád Farkas [email protected] 1
Environmental Physics Department, Centre for Energy Research, Konkoly‑Thege M. út 29‑33, 1121 Budapest, Hungary
alpha-particles originating from the decay of inhaled radon and radon progenies. In such a case, the spatial distribution of the induced biological damage may also be non-uniform. Earlier simulations confirmed indeed that, due to the special feature
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