METHOD FOR OBTAINING ACCURATE GEOMETRICAL COORDINATES OF NASAL AIRWAYS FOR COMPUTER DOSIMETRY MODELING AND LESION MAPPING

Recently, finite-element computer simulation of airflow in rat nasal a irways has been used to predict local and global xenobiotic mass trans port. These computer simulations have the capability to facilitate the extrapolation of experimental data from rats to humans for risk asses sment. Implementation of similar models of other species requires accu rate and detailed geometrical coordinates of airways. This article pre sents a sectioning method for the acquisition of airway coordinates an d morphometric data from fixed tissues. Using this method, airway tiss ue specimens are embedded in a frozen, contrast-enhancing medium and s erially sectioned. Video images are digitized from photographs of the block face, and image analysis is used to obtain geometrical coordinat es of the nasal passage perimeters. Calibration images and embedded al ignment marks are used to scale and align sequential sections. Data re sulting from the application of this method to a rhesus monkey specime n are reported, including a three-dimensional computer reconstruction of the data. Airway coordinates are also used to generate a set of dia grams suitable for lesion mapping for comparison with local dosimetry data derived from numerical simulations. This method improves on previ ously reported methods. Undistorted airway geometry is obtained by pho tographing the cut block face. Automatic thresholding to obtain coordi nates during image analysis is made possible by the contrast-enhancing medium. Automatic scaling and alignment of sections is facilitated by the use of calibration images and alignment marks. This coordinate ac quisition method has applicability to other complex biological passage ways.