Material property determination of sub-surface objects in a viscoelastic environment

Modeling human organs and soft tissue or anatomic regions for the purpose of medical training and simulation is a relatively new area. The data presented here is the groundwork for our ongoing development of a real-time haptic virtual environment for abdominal soft tissue palpation. The purpose of modeling the human abdomen is twofold. First, to provide a mathematical description of soft tissue and organs and second, to simulate the behavior of realistic interactions in real-time within a virtual environment. We have developed a, non-invasive, system that will allow us to determine mathematical functions that model the deformation of individual layers of soft tissue within the human abdomen. This system has been tested, experimentally, with a viscoelastic polyester foam model. We have been able to determine the stiffness and force/displacement function of an object beneath two layers of foam having different material characteristics. These experimental results correlate well with known polyester foam material characteristics. In general, the calculated stiffness constants were within 5% of the actual value. The data presented in this study shows that this system may be a viable tool for accurate measurement of human soft tissue properties and behavioral response to palpation.