Radon progeny measurements in a ventilated filter system to study respiratory-supported exposure

Radon (²²²Rn) and its progeny are responsible for half of the annual dose from natural radiation and the most frequent cause for lung cancer induction after smoking. During inhalation, progeny nuclides accumulate in the respiratory tract while most of the radon gas is exhaled. The decay of progeny nuclides in the lung together with the high radiosensitivity of this tissue lead to equivalent doses implying a significant cancer risk. Here, we use gamma spectroscopy to measure the attachment of radon progeny on an air-ventilated filter system within a radon enriched atmosphere, mimicking the respiratory tract. A mathematical model was developed to describe the measured time-dependent activities of radon progeny on the filter system. We verified a linear relation between the ambient radon activity concentration during exposure and the amount of decay products on the filter system. The measured activities on the filters and its mathematical description are in good agreement. The developed experimental set-up can thus serve to further investigate the deposition of radon progeny in the respiratory tract under varying conditions for determination of dose conversion factors in radiation protection, which we demonstrate by deriving dose estimations in mouse lung.