Medical robotics have started using methods of minimally invasive surgery as standard, and this technology has been used for remote operations i.e. tele-surgery. There is an actual case which exclusive communication lines were used during robotic tele-surgery. However, using special communication lines is not average method. So, the construction of the general robotic tele-surgical environments is required. In this paper, the simulation system is composed of three modules that have been developed to simulate signal characteristics in a public line. The modules are (1) QoS simulator algorithm, (2) QoS compensation algorithm and (3) Slave simulator algorithm. The requirement of the network QoS to establish the most suitable means of control was clarified. And then, an ultrasonic motor was driven and its performance was experimented to demonstrate the feasibility of (2) QoS compensation algorithm. The output value was compared with the input value of the ultrasonic motor. Buffering the network disorders was shown.

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We present a direct display method of surgical tool position and orientation in the surgical field by drawing twolaser beam planes, which is called “laser guidance method”. In this paper, the characteristic analysis of laser guidancewas also presented. The experimental results show the accuracy of laser guidance which the error was within 1.0mm forposition and within 1.0 degree for orientation. The theoretical analysis of laser guidance found out interesting behavior inthe tool adjustment procedure. Further, a monolithic integration of two laser devices with a three-dimensional positionsensor was designed using the result of workspace analysis. By the monolithic integration, feasibility of the system isexpected to be greatly improved since the monolithic integrated laser device requires no calibration and can be intraoperativelyrelocated. The details of the monolithic integrated system design were reported.

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Recently, development of instruments for minimally invasive surgery has been considerably required. In this research, we propose a master-slave system for laparoscopic surgery, which can provide the force feedback to the surgeon without force sensor. The prototype forceps manipulator has 3-DOFs at its tip, and pneumatic cylinders are used as actuator for them. We designed a bilateral dynamic control system using neural network for acquisition of the inverse dynamics. The obtained inverse dynamics is used for feed forward and estimation of the external force. Experimental results showed that the developed system successfully displays the contact force on the slave side to the operator.

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Neurosurgeons generally decide on the location to make an incision of a patient head at a surgical planning meeting. In the meeting, doctors speculate the 3-D image of a patient by using models of a normal brain, mannequins and the (2-D) slice images (MR, CT and so on). However, doctors have the different image of a patient because they have the different knowledge and experiences. Therefore, interactive surgical planning systems, which have tools to discuss about the approach of the operation (for example, the location to make an incision) with the 3-D patient data interactively in a virtual space, are useful for doctors to compensate the difference of the 3-D image between them at the meeting. In our research, we develop a fast volume editing method, which is based on texture-based volume visualization and use partial textures, to mark on the patient head and sulcus, and to remove tissue of the head and the tumor. Finally, we evaluate our method by questionnaires to neurosurgeons.

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An update-navigation system for the resection surgery of brain tumor was developed using newly designed fiducial markers and intraoperative magnetic resonance imaging (MRI). Sixty-seven patients underwent resection surgeries aided by this system. The aim of present study was to evaluate the registration error in the update-navigation system when the new markers were used. The registration error was measured for the difference between patient positions (prone and supine), between imaging conditions (T1-weighted and T2-weighted), and between surgeon's experience (experienced and less experienced), revealing no significant differences.
The registration error was 0.84±0.44mm (n=55) for prone position and 0.88±0.47mm (n=12, p>0.1) for supine position. The registration error was 0.90±0.35mm (n=45) for T1-weighted images and 0.75±0.45mm (n=22, p=0.08) for T2-weighted images. The registration error was 0.84±0.41mm (n=60) for the experienced surgeons and 0.98±0.73mm (n=7, p>0.1) for the less experienced ones.
The present results indicate that the new fiducial markers allowed the navigation system to have stable registration errors irrespective of patient position, imaging condition, and surgeon's experiences. Furthermore highly accurate resection surgery is assured with this navigation system when the new markers are used.

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Minimally invasive surgery has recently become a key word in medical engineering. In this operation, to introduce surgical instruments, spatulas which push tissues aside and retain the approach path to the affected area as well as workspace for the insertion of such instruments are necessary. Therefore, a new type of hydraulically-driven flexible manipulator for neurosurgery has been developed. With an attached balloon and using only physiological saline for the drive system, safety of the brain tissue, especially in terms of pressure, is assured as is the simplicity of the mechanism. In addition, this provides the advantage of MRI compatibility. We produced the prototype with 3 joints which has three degrees of freedom, and from the results of several evaluations, derived theoretical equations about pressure, flow rate and leak.

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