Estimation of absorbed fraction and specific energy of radon progeny for a Syrian adult tracheobronchial tree

Ondo Estimating the health effect of 222Rn progeny deposited on inner surfaces of airways regions is of great interest because 222Rn progeny are considered the major contributors in imparted energy to lung structures.

In this study, (CT) scan of a healthy, non-smoking Syrian volunteer male, 3D-Slicer 4.7.0 medical image processing software, Solidworks mechanical design software and MCNPX 2.5.B code were used to create the geometry and to evaluate the absorbed fraction and specific energy due to alpha particles emitted by inhaled radon progeny in nuclei and layers of sensitive cells in the epithelium of human trachea-bronchial tree. Absorbed fraction (AF) and specific energy were determined using Micro-dosimetry approach and airway tube wall as proposed by ICRP (1994), and NRC (1991).

Absorbed fractions (AFs) and specific energy of alpha particles were calculated for each generation from 1st to 15th. Comparison of average AFs values in sensitive layers was carried out with ICRP66 airway model where some significant differences were found due to dimensions differences between both models. Furthermore, AFs of cell nuclei had the same trend of those for layers, where the highest values were for 7.69 MeV alpha particles in BB region and the opposite in bb region. 

Interactions of alpha particles with secretory and basal cells show significant differences which can influence dose weightings. Comparisons with ICRP66 data reveal the influence of geometry and target cells distribution on absorbed fraction and specific energy values.