In this study, we have developed a wireless surgical navigation system with a multi Wi-Fi optical 3D tracking system for image-guided surgery. The proposed system can obtain position information using these two concurrently usable wireless systems to guide an instrument. As a result, it can eliminate the line-of-sight problem of tracking markers. Furthermore, the use of the multi Wi-Fi optical 3D tracking system reduces the need for connecting cables. Moreover, the system is highly robust owing to the unitization of the system components using Wi-Fi. The two navigation systems can guide the instrument concurrently using position information obtained from the tracking systems. Furthermore, they can easily perform re-registration by using the relative position of the tracking systems and the instrument position information. We evaluated the mean Target Registration Error (TRE) of the system by performing re-registration ten times. The mean TRE of the ten points of the phantom was found to be 1.43±0.75 and 1.43±0.77 mm by the fast Wi-Fi tracking system and the second Wi-Fi tracking system, respectively. Moreover, the mean TRE increased by at most 0.96 mm when re-registration was performed ten times. This suggests that our system has sufficient re-registration accuracy for navigation. Therefore, we believe that the developed system will be effective for image-guided surgery.

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Endoscopic sinus surgery (ESS) has been performed with a navigation system to reduce a risk of causing injuries and complications during the surgery. However, supporting the improvement of surgeons’ skill levels is important to further improve the safety of ESS. We previously developed a method for analyzing and evaluating the motion of the forceps during a glioma surgery and a laparoscopic cholecystectomy in order to help surgeons to learn surgical skills. As a surgeon need to operate an endoscopic camera and a forceps in the case of ESS, we focused on analyzing a camera operation. Therefore, in this study, we present a quantitative analysis method of a camera operation during ESS. By using the information obtained by a navigation system, we developed a method for quantifying a camera operation with five analytical parameters and estimating surgeons' skill levels based on discrimination analysis. For fundamental validation, we analyzed a camera operation during a simulated bone resection task for ESS using a nasal bone phantom. Eight surgeons (four experts and four novices) participated to the study and the task was performed five times by each surgeon. A total of forty procedures were analyzed to validate our method. Based on the validation results, we believe that our analytical method is effective for quantitatively analyzing and evaluating surgical performances without depending on years of experience.

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For ultrasound therapy, e.g. microbubbles delivery, physical contact between therapeutic device and body surface is important. To guarantee the entire contact of the device, we propose a control method considering contact force and reaction moment using a robotic system and sensors. We used a parallel link robot, which has three links and the holder to determine position and angle of the device. First we established a series of surface contact controls, which consists of (a) initial contact control, (b) balance contact control, and (c) angle restoration control. Second we eliminated self-weight moment of the device using the sensors. Next we proposed a measurement method of elasticity coefficient of soft material. Then we performed evaluation experiments using soft material and human body. In the experiment using soft material, contacted area was visualized and evaluated with color ink. In the experiment using human body, convergence time to the desired position and angle was also evaluated while monitoring contact force and moment. We concluded that the determination of appropriate parameters is important and dominant for the quality of the system.

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As computer aided surgery in microsurgery, vascularized fibula graft with three dimension (3D) bone model was performed on 3 cases. The cases consisted of one pseudoarthrosis of femur and 2 pseudoarthrosis of tibia. Computed tomography (CT) was performed preoperatively. Standard triangulated language (STL) file of bone models constructed from CT data. After input of STL file, 3D printer printed out 3D bone models made of acrylonitrile butadiene styrene (ABS) resin. The models which were sterilized by ethylene oxide, were used during the operation. In the operation with 3D bone model, we can gain an understanding of deformed bone shape easily, and transplants of vascularized fibula became smooth. In addition, the models might decrease the frequency of image intensifier scan during the operation. Here lists the benefit of preoperative modeling method in vascularized fibula graft ; easy understanding of deformed bone shape, down dose of radiation, smooth transplants of fibula, and shortening of operation time.

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