Fujio Tajima

Development of MR Compatible Surgical Manipulator toward a Unified Support System for Diagnosis and Treatment of Heart Disease

We propose a new concept of a unified system for supporting both surgical treatment and intrasurgical diagnosis of heart diseases, especially ischemic heart disease like myocardial infarction, under a magnetic-resonance-imaging (MRI) environment. In developing the system, we first designed and built a prototype of maneuverable manipulator as a subsystem. We then evaluated MR compatibility of the manipulator by moving its arm tip close to a phantom in the field of view of an open-configuration MR imager. No noticeable deformation, but some signal-to-noise ratio (SNR) deterioration, was observed in the MR images taken during evaluation. It is planned to combine the manipulator with other subsystems and function modules in order to construct an easy-to-use unified support system. This system will then be applied to treat a variety of diseases of organs and tissues in the human body.

A magnetic resonance compatible surgical manipulator: Part of a unified support system for the diagnosis and treatment of heart disease

A prototype of a magnetic resonance (MR)-compatible surgical manipulator was designed and evaluated. The manipulator is designed so as to fit into vertical magnetic field open-configuration MR imagers. Moreover, it is designed to work without being fixed to an MR imager, and its electrical circuits and lines of actuators and sensors are independent of the room shield so that it could be installed in various kinds of settings at many MR imager sites without any additional construction. The MR compatibility of the manipulator was evaluated: no noticeable deformation was observed in the MR images even when the manipulator was in motion. Although the signal-to-noise deterioration ratio was higher than that previously reported, the MR images were thought to be good enough for recognizing the whole structure of a targeted organ and for following the relative position of the manipulator tip with regard to the target, i.e. MR tracking.

Development of exchangeable microforceps for a micromanipulator system

TOSHIKAZU KAWAI 1;¤, KOUJI NISHIZAWA , FUJIO TAJIMA , KAZUTOSHI KAN 1, MASAKATSU FUJIE 1, KINTOMO TAKAKURA2, SHIGEAKI KOBAYASHI 3 and TAKEYOSHI DOHI 4 1 Mechanical Engineering Research Laboratory, Hitachi, Ltd., 502, Kandatsu, Tsuchiura, Ibaraki 300-0013, Japan 2 Tokyo Women’s Medical College, 8 Kawada-cho, Shinjuku-ku,Tokyo 162-8666, Japan 3 Shinshu University, School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan 4 Faculty of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

A prototype master-slave system consisting of two MR-compatible manipulators with interchangeable surgical tools: part of a unified support system for diagnosis and treatment

A prototype master-slave system consisting of two MR-compatible manipulators with interchangeable surgical tools was designed, implemented, and evaluated. The manipulators are designed so as to fit into vertical-magnetic-field open-configuration MR imagers. They are also designed so that the surgical tool mounted at the tip of their arm is interchangeable. The MR compatibility of the manipulator including a surgical tool was evaluated by moving it close to a phantom in the field of view of an open-configuration MR imager. No noticeable deformation, but deterioration in the signal-to-noise ratio of approximately 10 percent, was observed in the MR images. Consulted clinicians then evaluated the manipulability of the master-slave system by maneuvering a pair of slave manipulators through an operation input device consisting of a pair of master manipulators. After several minutes of trial and error, they could perform each primitive motion for suturing tasks on training material mimicking human tissue.

PALM-v/sup 2/: a passive articulated link mechanism with variable viscosity

Summary form only given. A new concept of passive articulated link mechanism is proposed to assist surgeons in the strong magnetic field of open configuration MRI, especially for neurosurgery. The core idea has been experimentally validated with the device which gives variable viscosity to cylinder rod motion by controlling the valve opening attached to the cylinder. Then a multiple degrees of freedom link mechanism is designed and simulated under several restrictions and constraints mainly concerned with space factors of the open configuration MRI and its field of view. Through this design and sequential simulation, it is concluded that the core idea could be extended to a multiple link mechanism suitable for neurosurgery.

An MR-compatible master-slave manipulator with interchangeable surgical tools.

Abstract This paper describes design, implementation and evaluation of a prototype of magnetic resonance (MR)-compatible master–slave manipulator with interchangeable surgical tools. The manipulator is designed so as to fit vertical-magnetic-field open-configuration MR imagers. Also, it is designed so that the surgical tool at the arm tip is interchangeable. We evaluated MR compatibility of the manipulator including a surgical tool by moving it close to a phantom in the field of view of an open-configuration MR imager. No noticeable deformation, but some signal-to-noise ratio (SNR) deterioration, was observed in the MR images. Consulted clinicians then evaluated its manipulability by maneuvering the master–slave manipulator system. After several-minute trial and error, they could perform each primitive motion for suturing task to training materials.

Intra-operative guidance with real-time information of open MRI and manipulators using coordinate-integration module

Assuming the surgery under open magnetic resonance imaging (MRI) equipment with manipulators, we developed the coordinate-integration module and the real-time functions that could display the manipulators position on the volume data of MRI and could obtain the cross-section images of MRI at the manipulators position. The small field of view from an endoscope is the problem in most of the minimally invasive surgeries with manipulators. Therefore, we propose an endoscopic surgery with manipulators under open MRI equipment. The coordinate-conversion parameters were calculated in the coordinate-integration module by calibration with an optical tracking system and markers. The delay of the manipulator-position display on the volume data was approximately within 0.5 second though it depended on the amount of the volume data. We could also obtain the cross-section images of MRI at the manipulators position using the information from the coordinate-integration module. With these functions, we can cope with the change of the organ shape during surgery with the guidance based on the individual information. Furthermore, we can use the manipulator as an MRI probe to define cross-section position like an ultrasonic probe.

Bipolar coagulation - capable microforceps

Microforceps that can be used with the hyper utility mechatronic assistant system (HUMAN) for bipolar coagulation in minimally invasive neurosurgery were developed. A method of using two sets of those forceps for bipolar coagulation was developed, in which electrical current is passed through the drive wires to the forceps tips to form an electrical circuit. A prototype mechanism that employs a torque tube to achieve an opening and closing speed of 138/spl deg//s was fabricated. A forceps drive system that has a delay time of 0.06 s was constructed by using a fast control algorithm. In vivo experiments on rat abdomen and rat brain blood vessels confirmed that the bipolar coagulation function is of a practical level. Three neurosurgical clinicians confirmed the good operability and practicality of the gripping function in experiments on a human cadaveric brain. Furthermore, both doctors and engineers confirmed that the microforceps described here can be used in their present form in tumor removal and other such procedures. Following these basic engineering experiments, basic medical experiments (including experiments on the optimum distance between the lens of the endoscope and, the object of manipulation), various surgical procedures performed on living rat brain, surgical simulations performed on a human cadaver, and experiments on safety in ethylene oxide gas sterilization were performed. They lead to the conclusion that clinical use of the HUMAN system is feasible.

Development of HUMAN system with three micromanipulators for minimally invasive neurosurgery

Abstract A microsurgery assisting system for minimally invasive neurosurgery has been developed. Three sets of micromanipulators and a rigid endoscope are integrated together in a thin tubular insertion part. Each manipulator has three degrees of freedom and controlled through the control levers on the console. The manipulator has tubular structure, which allows a thin operating device to travel through it. It has been verified that the device can take up in-vivo tissue and the laser knife works well with the manipulator.

Optimal design method for dynamic vibration absorbers installed in multijoint mechanisms

In order to achieve fast robotic movement, a control system with a fast response time achieved by using a velocity control unit with high proportional control gain is needed. However, low-frequency mechanical resonance is a limitation. Installation of dynamic vibration absorbers is an effective method for decreasing the resonance peak and increasing the proportional gain. This paper proposes an optimal design method for dynamic vibration absorbers installed in multijoint mechanisms. The absorbers are driven by several motors and have dynamic coupling axes. Results of an experiment using a mechanisms with and without absorbers, are described and the validity of the proposed design method is confirmed.<<ETX>>