Modeling interactions with a computer representation of the upper gastrointestinal system.

Our goal is to simulate interactions with a computer model of the esophagus and the stomach, built from the Visible Human database, and reported in previous works. The optical distortion of the endoscope was simulated during navigation allowing the user a quantitative assessment of distortion when measures an injury. Another improvement to our model is the inclusion of abnormal anatomy, from two types, the first one is related to the color features of the disease and the second is a direct modification in the triangle structure of the mesh, with the goal to simulate blisters and injures in the model. The esophagus in its natural state presents radial collapsing, which was simulated using finite element methods. To this collapsed state we superposed the interaction of the triangle mesh with a model of the air pressure against the walls. The collapsed state allows to train the user in the insertion of the endoscope and to assess the effects of friction between the walls and the instrument.