Cellular lung dosimetry for inhaled radon decay products as a base for radiation-induced lung cancer risk assessment. II. Microdosimetric calculations.

Lung dose calculations for inhaled radon decay products presented in part I have revealed that mean basal cell doses are significantly dependent on various personal and environmental factors. Whereas these macroscopic dosimetric methods have been applied with great success to radiation protection problems, the interpretation of radiobiological effects, such as lung cancer incidence, needs some refinement of these methods. Energy deposition at the microscopic level as the physical input quantity and radiation carcinogenesis as the biological endpoint are by nature stochastic processes. Therefore, a microdosimetric model was developed taking into consideration the randomness of physical and biological parameters involved, Part II of the paper presents results on specific energy distributions in lung cells, demonstrating that single event density distributions together with the number of cells receiving single hits represent more appropriate parameters than mean radiation doses.