Three-dimensional simulations of airways within human lungs

Information regarding the deposition patterns of inhaled particles has important implications to the fields of medicine and risk assessment. The former concerns the targeted delivery of inhaled pharmacological drugs (aerosol therapy); the latter concerns the risk assessment of inhaled air pollutants (inhalation toxicology). It is well documented in the literature that the behavior and fate of inhaled particles may be formulated using three families of variables: respiratory system morphologies, aerosol characteristics, and ventilatory parameters. It is straightforward to propose that the seminal role is played by morphology per se because the structures of individual airways and their spatial orientations within lungs affect the motion of air and the trajectories of transported particles. In previous efforts, we have developed original algorithms to describe airway networks within lungs and employed them as templates to interpret the results of single photon emission computed tomography (SPECTs) studies. In this work, we have advanced the process of mathematical modeling and computer simulations to produce three-dimensional (3D) images. We have tested the new in silico model by studying two different branching concepts: an inclusive (all airways present) system and a single "typical" pathway system. When viewed with the glasses supplied with this volume, the 3D nature of airway branching networks within lungs as displayed via our original computer graphics software is clear. We submit that the new technology will have numerous and seminal functions in future medical and toxicological regimens, the most fundamental being the creation of a platform to view natural 3D structures in vivo with related biological processes (e.g., disposition of inhaled pharmaceuticals).