ing to deformation from experimentally obtained force/deflection curves. Andrew Mor of the Robotics Institute at Carnegie Mellon (Mor, 1998) has used the PHANToM in conjunction with a 2DOF planar device so that the new device would generate a moment measured about the tip of a surgical tool in an arthroscopic surgery simulation, thus providing a more realistic training for the kinds of unintentional contacts with ligaments and fibrous membranes that an inexperienced resident might encounter. At MIT, De and Srinivasan (1998) have developed models and algorithms for reducing the computational load required to generate visual rendering of organ motion and deformation and the communication of forces back to the user resulting from tool-tissue contact. They model soft tissue as thin-walled membranes filled with fluid. Force-displacement response is comparable to that obtained in in vivo experiments. Giess, Evers, and Meinzer (1998) integrated haptic volume rendering with the PHANToM into the pre-surgical process of classifying liver parenchyma, vessel trees and tumors. Surgeons at the Pennsylvania State University School of Medicine in collaboration with Cambridge-based Boston Dynamics used two PHANToMs in a training simulation in which residents passed simulated needles through blood vessels, allowing them to collect baseline data on the surgical skill of new trainees. Iwata, Yano, and Hashimoto (1998) report the development of a surgical simulator with a "free form tissue" which behaves like real tissue, e.g., can be cut. Gruener (1998), in one of the few research reports which expresses reservations about the potential of haptics in medical applications, found that subjects in a telementoring session did not profit from the addition of force feedback to remote ultrasound diagnosis. There have been a few projects in which haptic displays are used as alternative input devices for painting, sculpting and computer-assisted design. At CERTEC, ...
