The development of minimally invasive cardiac surgery has been limited becaouse of poor visualization and increased technical difficulties in carrying out operations through ports. Cardiac surgery will be technically feasible with use of robotic instrumentation. This technology may enable the development of a truly approache to cardiac surgery. We have performed the first cases of mitral valvoplasty and harvesting of left internal thoracic artery using sophisticated robotic instrumentation of ''da Vinci'' system.

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VR technology mainly includes surgical navigation system, image-guided surgery and robotic surgery. All of them sre assisted by computer technology. This technology would support conventional endoscopic surgery and overcome its technical difficulties, resulting in providing less stressful as well as safer and more precise surgery to us.

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We have developed the first prototype system of a neurosurgery simulator. It is developed for amedical training of cerebral aneurysms operation. This paper describes the artery model of the simulator. The system is equipped with a binocular microscope type of stereo view display, a foot pedal for its manipulation, and input devices as surgical tools such as spatula and clip. As for the procedure, operators first move arteries with a spatula in the left hand and take a cerebral aneurysm to a proper position. Then they pick up the aneurysm firmly with a clip in the right hand, and release the tip of the clip, which remains at the aneurysm position. In order to simulate the surgery in real-time, spring based model is adopted for an artery deformation and a simplified model is for surgical tools. Both models are approximated as line segments. As a result, the collision detection problem is dolved as intersection calculation of two line segments. The performance could reach to 37 Hz. The next target is a network-based remote education system with haptic device.

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In this paper, the present state and the future of virtual endoscopy (VE) are stated. VE is a system which can generate endoscopic images of inner organs only using 3D CT images of a real human body. This new diagnostic tool has advantage that can be applied to patients without pain, and that enables us to observe the state of inner human body from any position and direction. Usually, VE should have several basic functions including rendering, segmentation, measurement and user interface. Recently, some advanced functions for abnormal lesion detection, simultaneous display of real and virtual endoscopic images and organ deformation with force feedback have been also investigated. VE can be applied to many fields including diagnosis, surgery and medical education, and some systemd have already been in clinical use.

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Virutal reality (VR) and robotics will have a major impact on medical education. They are emergine technologies that can educate students and teach surgeons new surgical procedures. They can evaluate their level of competence befor and after the surgery, because both of robotic and laparoscopic surgery popularized clinically. High performance medical image processing is also to play an important role in surgical planning and VR simulator can realize quantitative measurement of competence by using surgical manipulation data from robotic and laparoscopic mechanical devices. VR might be used to further enhance medical education and assist in the surgery of a wide variety of diseases. In the present paper, various surgical educations using virtual reality technology are discussed, along with the technological developments needed to make them possible.

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Health maintenance is inevitable especially in the case of elderly people. Horse back riding therapy, which was developed in Europe, has been found to be effective in satisfying the health care needs. Since riding does not cause any psychological burden, it can be described as a training to regain physical functions suitable for the elderly. The only drawback is thet one need to have access to live horses, which limits the wide spread application of this method. To address this problem and to make the therapy available to healthy elderly people, we have been developing horseback riding therapy system using VR Technology. This paper aims at describing two versions of such developed equipment. The First version reproduces both the precise movements of the saddle and a stripped down and the second one is a home use system that employs a simpler and more cost-effective mechanism yet achieves the purpose of a physical training. The system is found to be effective in improving abdominal strength, back strength, and the strength of both extension and flexing of knee musckles. The system is also proved to be effective in preventing stumble, fall and backaches arising from deformed body postures.

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Minimally invasive surgeries have become popular in the fields of cardiovascular and abdominal surgery. Since dificulty of the surgeries depends on their approaches, the system that enables surgeons to rehearse procedures in constructing surgical fields is useful and required. However, most of current surgical planning systems are not applicable to simulate whole process of the procedures because they cannot deal with complex physical behaviour of soft tissues. This paper proposes to establish a virtual reality based planning system of surgical approaches using an adaptive physics-based framework. The framework provides finite element based deformation in real time inaddition to interactive soft tissue cutting, and generates virtual surgery fields effectively. Also, the developed system gives a palpation environment to identify arterial sclerosis in the reconstructed surgical field. This paper evaluates characteristics of the visual and haptic framework and verifies the performance of the proposed system.

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For tele-robotic surgery, immersive view or precise view of operating field with live video streaming is indispensable. However, the given view is limited in viewing angle, quality, and resolution by the ability of instruments. Video streaming delay is unavoidable by the limitation of the network. The purpose of this report is to research the main factor of difference between skillful operators and skill-less operators under telesurgery environment. By the experiment, the skill of subjects was evaluated in the target-pointing task on the Surgical Cockpit System. The subjects were classified into skillful group and skill-less group by frequency of mistakes. Accuracy of posture of surgical instrument, time for task operation, and total path length of surgical manipulator were compared between two groups. The main difference was shown in the total movement. Total path length was significantly short, moreover, the path length was not varies under different conditions. The difference between skillful subjects and skill-less subjects were enlarged by the video streaming delay.

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A good force display in the fields of virtual reality, remote control, various training, designing, medical care and welfare and so on will increase the feeling of being at the scenes enhancing thus the effectiveness and efficiency. Most of the force display systems being into practical use are not enough large size for such applications. On the other hand, a force display system for upperlimbs, different from systems for fingers or hands, needs to exercise a whole limb. The system therefore requires a large working space, a large display ability and a good back-drive ability. Such a system is equal to robot system, but is different too from current industrial robots. The system is operated in constant contact with the trainee, and there is always the possibility of collision with and injury to the operator. Thereby it is necessary for operators to be able to use the system safely under any circumstances or conditions. The authors propose the application of an ER fluid apparatus to force display system that have large wok space and generative force and consider safety introducing force display systems they have developed, and consider the application of systems to medical education.

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This paper describes the architecture of real-time surgical simulators. First of all, a high performance graphics workstation based real-time simulation so that it could supply the user demand; however, there remained one problem of the cost. Then, the next simulator was developed with a personal computer in order to reduce the system cost and also new software simulating another surgery case was developed. Especially, the cost of a stereo display and haptic devices, both of which were the core components of the system and occupied the large ratio of the cost, were reduced by specifying the functions of them for ocular surgery. As a result, we succeeded in establishing a simulator that could supply the user demand of boty functions and the cost. Therefore, it has been tried to develop a neurosurgery simulator with the same components as that of the ocular surgery one. Although it remains the problem of haptic display, it is found that the specification of the stereo view can apply to not only ocular surgery but aloso neurosurgery simulators.

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As increasing minimally invasive surgery, many researcher developed surgical navigation systems. These systems often visualize images that could not see directly, by superimposing images from MRI, CT etc. to real patients image. Such systems support the operator to know the relationship between the target area and the other vital area in the patients body. However, they do not support the task itself because they only visualize the data. In this paper, we propose force navigation system, which generates appropriate force between the tool that the operator holds and the target area of the patients body to navigate the tool. By using force sensation, the system could navigate the tool and support operators task directly. Furthermore, we describe about the experimental system, which intend to support surgical operation of pituitary adenoma.

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