Mimicking lung dose by wire-mesh-capped deposition sensors: a new dosimetric strategy of radon (thoron) decay products.

The dose conversion factor (DCF) of radon decay products may vary by a factor of ∼40 within the particle size range from ∼0.5 nm to tens of micrometres. An ideal detector should have a response, which closely mimics the strong dependence of the DCF on the particle size. This dependence is essentially determined by the different deposition rates of the particles with different sizes on the trachea-bronchial tree and alveoli. These deposition rates versus the particle sizes are similar to those of the decay products onto indoor surfaces. These conclusions are conducive to a new strategy for the dosimetry of radon (thoron) decay products, which is simply based on the detection of decay products deposited on flat surfaces. The dependence of the deposition rate of radon decay products onto flat surfaces versus the particle size is necessarily different from that of the deposition rate on the trachea-bronchial region, especially for particle sizes smaller than a few nanometres and larger than a few micrometres. In the present work, in order to obtain a better mimic between the measurement of flat-surface-deposited radon (thoron) decay products and the DCF at any given particle size, a suitable screen is placed against the surrogate surface, used for the assessment of the radon (thoron) decay products deposition.