Development of an Advanced Micro-neurosurgical Robotic System for the Deep Surgical Field Shoichi Baba, Daisuke Asai, Shin’ichi Warisawa, and Mamoru Mitsuishi School of Engineering The University of Tokyo 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan {baba,daisuke,warisawa,mamoru} @nml.t.u-tokyo.ac.jp Akio Morita and Shigeo Sora Dept. of Neurosurgery, Faculty of Medicine The University of Tokyo 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8655, Japan {amor-tky,sora-tky}@umin.ac.jp Ryo Mochizuki and Takashi Shiraishi NHK Engineering Services, Inc. 1-10-11, Kinuta, Setagaya-ku, Tokyo 157-8540, Japan r-mochi@cyborg.ne.jp, shirais@nes.or.jp Abstract— In neurosurgery, surgeons have to perform minute and precise manipulations with poor visibility due to blood or cerebrospinal fluid. It is particularly difficult to operate in the deep surgical field. The authors have developed a microsurgical robotic system for the neurosurgery which overcomes these difficulties with precision of mechanical system. However, it was difficult for surgeons to operate the system skillfully without long training. Therefore, to ease the operation, the authors have developed a method to realize an intuitive motion with correspondence between the master and the slave manipulators, and also have developed a method to offer the information of spatial limits of the slave manipulator to operators. The experimental results showed the effectiveness of the developed system. Index Terms— Microsurgery, Neurosurgery, Robotic Surgery, Master-Slave System I. I NTRODUCTION In recent years, medical technology has been sophisti- cated with the introduction of engineering. Neurosurgery has progressed rapidly owing to the introduction and the spread of surgical microscopes in the 1970s. The develop- ment of the surgical microscopes provided an environment where microsurgery could be routinely executed in an enlarged operation field. That enabled surgeons to perform safely and precisely various kinds of operative techniques which had been almost impossible in conventional surgery with the naked eye. However, it is still a challenge to reduce the invasiveness of microsurgery while protecting normal brain tissue during surgery. Many systems to support operative techniques have been developed. da Vinci [1] and ZEUS [2] are already available commercially and have been used in many clinical appli- cations. However, they are not appropriate for minimally invasive neurosurgery because they were developed to support laparoscopic or cardiosurgery, and their insertion probes are more than 10 mm in diameter, which is too thick to insert in the craniotomy hall. In neurosurgery, robotic systems to support operative techniques have been developed [3], and NeuRobot [4] and RAMS [5][6] have adopted master-slave systems to support microsurgery. In master-slave surgical systems, the operation site and the surgical site are designated as the master and the slave respectively. Micro-manipulation is performed by scaling the master and the slave manipulator motions [7]. The HUMAN system [8][9] is a master-slave microsurgical system for neurosurgery. Its insertion probe is 10 mm in diameter and contains a stereoscopic endoscope and 3 micro forceps, each of which is 3 mm in diameter and has 3 D.O.F. However, the motion range is limited to a 10 mm cube, which is not large enough to complete a surgical operation, such as suturing or removing tumors. The neuroArm [10] is also a master-slave microsurgical system for neurosurgery. It has 8 D.O.F. for each arm of left and right arms, and MRI-compatible. The design of the system has been completed, however, it has not been developed yet. Therefore, neurosurgical robotic system that has enough motion range to complete neurosurgical operations in the deep surgical field has not been developed. To solve these problems, the authors have constructed a micro-surgical system [11][12] for neurosurgery to assist micro-manipulation in the deep surgical field. However, it was difficult for surgeons to operate the system skillfully without long training. II. DESIGN OF A NEUROSURGICAL SYSTEM A. Concept To decrease the invasiveness of neurosurgery, it is nec- essary to provide a sufficiently enlarged image of the target and precise maneuverability to the surgeon. The former requirement is fulfilled with by higher-powered sur- gical microscope. However, the latter requirement depends mostly on surgeon’s personal skill, which is acquired by specialized training and refined through experience and continual application. Therefore, the robotic surgical assis- tance system is expected to be used in difficult operative procedures such as the operations in the deep surgical fields. The requirements and necessary conditions for a robotic surgical assistance system for neurosurgery are as follows: