The transfer of radon from thermal water via the skin to different human organs in radon therapy can experimentally be determined by measuring the radon activity concentration in the exhaled air. In this study, six volunteers were exposed to radon-rich thermal water in a bathtub, comprising eleven measurements. Exhaled activity concentrations were measured intermittently during the 20 min bathing and 20 min resting phases. Upon entering the bathtub, the radon activity concentration in the exhaled breath increased almost linearly with time, reaching its maximum value at the end of the exposure, and then decreased exponentially with time in the subsequent resting phase. Although for all individuals the time-dependence of exhaled radon activity was similar during bathing and resting, significant inter-subject variations could be observed, which may be attributed to individual respiratory parameters and body characteristics. The simulation of the transport of radon through the skin, its distribution among the organs, and the subsequent exhalation via the lungs were based on the biokinetic model of Leggett and co-workers, extended by a skin and a subcutaneous fat compartment. The coupled linear differential equations describing the radon activity concentrations in different organs as a function of time were solved numerically with the program package Mathcad. An agreement between model simulations and experimental results could only be achieved by expressing the skin permeability coefficient and the arterial blood flow rates as a function of the water temperature and the swelling of the skin.

中文翻译：

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氡疗法中氡从热水转移到人体器官：呼气测量和模型模拟。

氡疗法中氡从温泉水中经皮肤转移到人体不同器官的情况可以通过测量呼出空气中的氡活度浓度来实验确定。在这项研究中，六名志愿者在浴缸中接触了富含氡气的热水，包括十一次测量。在 20 分钟沐浴和 20 分钟休息阶段间歇测量呼出的活性浓度。进入浴缸后，呼出气中的氡活度浓度随时间几乎呈线性增加，在暴露结束时达到最大值，然后在随后的休息阶段随时间呈指数下降。尽管对于所有个体来说，在沐浴和休息期间呼出的氡气活动的时间依赖性是相似的，但可以观察到显着的受试者间差异，这可能归因于个体呼吸参数和身体特征。氡气通过皮肤的输送、其在器官中的分布以及随后通过肺部呼出的模拟是基于 Leggett 及其同事的生物动力学模型，并通过皮肤和皮下脂肪室进行了扩展。使用 Mathcad 程序包对描述不同器官中氡活度浓度随时间变化的耦合线性微分方程进行数值求解。只有通过将皮肤渗透系数和动脉血流量表示为水温和皮肤肿胀的函数，才能实现模型模拟和实验结果之间的一致性。