Deformation and cutting algorithm of an organ model used for a laparoscopic surgery simulator

With the recent development of endoscopic instruments, laparoscopic surgery has come into widespread use. Compared to traditional open abdominal surgery, the method offers a reduction of the physical burden on the patient, the in-hospital period, and the recovery period. On the other hand, more technical training is required compared to open surgery, since the surgery is conducted by observing a two-dimensional image obtained by laparoscopy. Many simulators for training have been developed in various research institutions. Most of these, however, require expensive high-performance hardware, and there is a need for a low-cost PC-based virtual laparoscopic surgery simulator. The important issues in constructing such a simulator are a forceps input device and an organ model representation which can be deformed or cut. This paper reports both a forceps input device and an organ model which can be deformed and cut. The organ model consists of a mass-spring model. In the deformation algorithm, an equation for force-displacement balance is used. When the forceps contacts an object, mismatching of the model deformation is eliminated by fine segmentation of the area surrounding the point of contact. When an object is to be cut, the fine segmentation area surrounding the area of contact with the forceps is enlarged with the progress of the incision area, maintaining the continuity of the process.