Predictions of inter- and intra-lobar deposition patterns of inhaled particles in a five-lobe lung model.

Objective: To develop a stochastic five-lobe lung model and to compute particle deposition fractions in the five lobes, considering anatomical as well as ventilatory asymmetry.

Materials And Methods: The stochastic five-lobe lung model was derived from an existing stochastic model for the whole lung, which implicitly contains information on the lobar airway structure. Differences in lobar ventilation and sequential filling of individual lobes were simulated by a stochastic lobar ventilation model.

CELLULAR DOSE DISTRIBUTIONS OF INHALED RADON PROGENY AMONG DIFFERENT LOBES OF THE HUMAN LUNG.

Basal and secretory cell doses in the different lobes of the human lung following inhalation of short-lived radon progeny were calculated for a five-lobe asymmetric, stochastic lung model, considering the non-uniform ventilation of the lobes. Dose calculations for defined exposure conditions revealed that the upper lobes receive higher doses than the average bronchial dose for the whole lung, with the right upper lobe receiving the highest dose. The resulting inter-lobar distribution of cellular bronchial doses indicated that the non-uniform lung morphometry is the dominating factor, while non-uniform ventilation only slightly enhances the lobar differences.

The degree of inhomogeneity of the absorbed cell nucleus doses in the bronchial region of the human respiratory tract.

Inhalation of short-lived radon progeny is an important cause of lung cancer. To characterize the absorbed doses in the bronchial region of the airways due to inhaled radon progeny, mostly regional lung deposition models, like the Human Respiratory Tract Model (HRTM) of the International Commission on Radiological Protection, are used. However, in this model the site specificity of radiation burden in the airways due to deposition and fast airway clearance of radon progeny is not described.

Radon transfer from thermal water to human organs in radon therapy: exhalation measurements and model simulations.

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.

Radon in the Exhaled Air of Patients in Radon Therapy.

In the Gastein valley, numerous facilities use radon for the treatment of various diseases either by exposure to radon in air or in radon rich thermal water. In this study, six test persons were exposed to radon thermal water in a bathtub and the time-dependent radon activity concentration in the exhaled air was recorded. At temperatures between 38°C and 40°C, the radon activity concentration in the water was about 900 kBq/m3 in a total volume of 600 l, where the patients were exposed for 20 min, while continuously sampling the exhaled air during the bathing and 20 min thereafter.