[Stochastic model for the spatial visualization of particle-deposition patterns in the lung and their significance in lung medicine].

The present paper provides a detailed description of an extension of the Monte Carlo computer model IDEAL, which enables the generation of spatial particle deposition patterns in the human lung. Randomly determined particle trajectories are transformed to a Cartesian coordinate system within which the orientation of the trachea corresponds to the z-direction. At the same time, the determination of particle deposition sites is carried out by application of a grid composed of specific volume elements (voxel). The calculation of particle deposition are based on the physical mechanisms of Brownian diffusion, sedimentation, and inertial impaction. After their storage in a matrix, the deposition data are subject to graphical processing. This allows the presentation of spatial particle distribution patterns (3d-density plots) and of the lung surface itself as well as the generation of two-dimensional distributions by sectioning the three-dimensional structures at pre-defined positions. The results of different model simulations (variation of particle size and breathing conditions) are discussed in detail.