When using an oblique-viewing scope, the rotation of cylinder changes the optical axis of the endoscopic camera. Thus, the angle of rotation is required to estimate the viewing direction in addition to the posture of the cylinder. In a previous study, rotary encoder is used for acquisition of the rotational angle of the cylinder. However, the rotary encoder tends to be cumbersome in clinical use, because the encoder must be attached between a cylinder and a camera head. In this study, we estimate rotation angle of the cylinder by using an accelerometer. The accelerometer detects the orientation of gravity. The rotation of the cylinder is calculated from the change of the orientation of the gravity. Besides, we considered the influence of movement of the endoscope on the accelerometer and executed movement decision. The result of experiments indicated that the method enabled to estimate the rotation angle within about 3 degrees of errors when the endoscope is inclined at an angle of less than 45 degree against the horizontal plane.

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In general, minimally invasive surgery is the most difficult surgery because a field of view of an endoscope is limited and force sensation from surgical tools such as forceps is poor. Especially in early clinical education for medical students, a virtual reality surgical simulator will be an effective tool. In this paper, we propose a visuohaptic surgery training system for laparoscopical techniques. We recorded a video from the first person perspective and operation information of surgical tools of a trainer. And then, we displayed the recorded video and the guidance force to trainees. We constructed a prototype surgery training system, and effectiveness of our approach was confirmed.

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We propose a VR-based injection training system using Simulated Patient (SP) with an original haptic needle which can represent a haptic expression. SP is trained to realistically portray a real patient. In order to increase a realistic sensation and effect of training, it is important to train with real human. Therefore we propose a new training system which fuse SP and virtual training system. In the proposed system, trainee can virtually puncture the SP using the haptic needle. In addition, the haptic needle can represent a haptic expression of needle insertion of the virtual anatomical model. We developed the haptic needle which can represent a reaction force of puncturing. A reaction force of needle insertion is generated by clipping needle by using computer-controlled electromagnet and permanent magnet, and then a friction force is accrued. By using the proposed system, trainee can feel virtual puncture as well as operating for real patient.

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Objective: To preoperatively predict the facial nerve location more accurately in patients undergoing surgery for large vestibular schwannoma. Method: First, three-dimensional (3D) models of arteries and veins around the tumor are combined with contrast-enhanced (CE) fast imaging employing steady-state acquisition (FIESTA) to detect the nerve more accurately. Second, a 3D model of the nerve is constructed to investigate its three-dimensional location. Then, the nerve, which keeps continuity to internal auditory canal or brain stem and runs in the direction of brain stem to internal auditory canal, is recognized as the facial nerve. Result: Using this method, the facial nerve was detected in seven of 10 patients. Conclusion: In large vestibular schwannoma, this method can detect the facial nerve more accurately than existing reports.

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