Computers and Robotics Proceedings of the Xth Meeting of the World Society for Stereotactic and Functional Neurosurgery, Maebashi, Japan, October 1989 Stereotact Funct Neurosurg 1990:54+55:462-467
Development of a New Microsurgical Robot for Stereotactic Neurosurgery Hiroyuki Koyama a , Tateki Uchida3, Hiroyasu Funakuboa , Kintomo Takakurah, Heinz Fankhauser1 J Center of Education and Research, Shibaura Institute of Technology, Saitama: b Department of Neurosurgery, Faculty of Medicine, University of Tokyo, Japan; c Department of Neurosurgery, Universitaire Vaudois, Lausanne, Switzerland
Key Words. Stereotactic surgery • Biopsy • Robot • Microneurosurgery Abstract. The robot technology was introduced into a new stereotactic neurosurg ery system for applications to biopsy, blind surgery, and functional neurosurgery. The authors have developed a newly designed prototype microsurgical robot, designed to allow a biopsy needle to reach the target such as a cerebral tumor within a brain automat ically on the basis of the X, Y, and Z coordinates obtained by CT scanner. This robot is so small that it can be driven in a CT scanner gantry. It consists mainly of the link mech anism and the insertion mechanism. We constructed the link mechanism and investi gated its working space.
Introduction
© I990S. Karger AG. Basel 1011-6125/90/0554-0462 S 2.75/0
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CT-guided stereotactic surgical procedures, which employ a CT scanner for the localization of the target, have been recently estab lished as the newest technology and are classified into two groups; (1) operation is performed in the operating room after measuring the posi tion of a lesion in a CT room and transporting the patient to the operat ing room, and (2) CT measurements and operation are performed in a CT room [1], For the latter group, several CT-guided stereotactic surg ery systems had been developed. In 1985, Kwoh presented the CTguided stereotactic surgery system which employed an industrial robot (Unimation Puma 200 robot) [2, 3]. Our research relates to the develop-
Development of a New Microsurgical Robot
463
Fig. 1. Block diagram of the CT-guided stereotactic neurosurgery system employing the microsurgical robot.
ment of a new microsurgical robot system for neurosurgery. We de scribe the mechanism and the working space of a new microsurgical ro bot which is computer controlled, so that a biopsy needle can automat ically reach the target within a brain. This robot is characterized by its light weight and small size, so it can be easily attached to an operating table or a CT table.
Construction of the CT-Guided Stereotactic Neurosurgery System
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The block diagram of our CT-guided stereotactic neurosurgery system is shown in figure 1. The position data of a lesion obtained by a CT scanner are transferred to a personal computer. The three-dimen sional coordinates of the target are calculated by the computer, and then the computer generates control signals for the microsurgical ro bot. The position of the robot is measured with a position-sensitive de vice. The robot is feedback controlled through the computer by using the position data from the position-sensitive device. The position of the biopsy needle within the brain is displayed on the CRT screen.
Koyama/Uchida/Funakubo/Takakura/Fankhauser
464
Design Requirements of the Microsurgical Robot for Stereotactic Neurosurgery
We designed the microsurgical robot in consideration of the fol lowing design requirements: (1) the robot must be small enough to be driven within a CT scanner gantry; (2) the robot is positioned at the upper side of the head (Z axis) when a patient is lying on a CT scanner couch (with a dorsal or ventral position); (3) interference with the sur geon’s maneuvers must be avoided; (4) assuming that the head of a pa tient is a sphere (diameter 200 mm), the tip of the biopsy needle has to reach any position within the sphere; (5) the maximum depth of inser tion is 100 mm; (6) the biopsy needle is inserted into the brain through a burr hole made previously, and (7) the needle is inserted at any angle to the skull to avoid damage to functionally important regions and im portant vascular structures.
Mechanism of the Microsurgical Robot
Our new microsurgical robot consists of two parts. One is the in sertion mechanism which inserts a biopsy needle into the brain at any angle to the skull. The other is a link mechanism which moves the inser tion mechanism at any position on the sphere surface near the patient’s head. The insertion mechanism is attached to the one end of a moving link of the link mechanism.
Link Mechanism for Positioning
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Generally, three degrees of freedom are required to position the in sertion mechanism at any position near the patient’s head. But, assum ing that the shape of the head is a sphere, only 2 degrees of freedom are required to position the insertion mechanism at any position on a vir tual hemisphere around the head. Therefore, we designed the link mechanism with 2 degrees of freedom which allows the insertion mech anism to be positioned anywhere on the hemisphere. This spherical motion is realized by employing a circular motion mechanism and rotating this circular motion mechanism itself. The circular motion mechanism employing the link mechanism is shown in figure 2. The
Development of a New Microsurgical Robot
465
Fig. 3. Link mechanism.
circular motion mechanism consists of 5 links interconnected by six revolving joints. If we rotate link 5 (DE) around the axis of joint E, the trajectory of one end (Q) of link 2 (BQ) will be a circle. At the same time, if we rotate the whole body of the circular motion mechanism around the axis DE (Z axis), the total trajectory of Q will be a spherical surface. Figure 3 shows a photograph of the link mechanism part.
Insertion Mechanism of a Biopsy Needle
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We must take into consideration the relative locations of a lesion and a burr hole to design the insertion mechanism. If the burr hole is not perforated on a straight line which passes through the centers of the
Koyama/Uchida/Funakubo/Takakura/Fankhauser
466
virtual sphere and the target, we must rotate the supporting point of the biopsy needle to point the needle toward the target. Therefore, the in sertion mechanism requires two degrees of freedom which allow the bi opsy needle to rotate around two perpendicular axes. Furthermore, one more degree of freedom is required to insert the biopsy needle along the straight trajectory. Totally three degrees of freedom are re quired for the insertion mechanism. The sketch of the insertion mech anism is shown in figure 4.
Working Space of the Microsurgical Robot
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We examined the working space of our microsurgical robot by computer simulation. The result is shown in Figure 5. The robot can cover one fourth of the virtual sphere. If the diameter of a burr hole is 10 mm, and the distance of the needle-supporting point from the burr hole is 50 mm, the working space of the biopsy needle is inside a cone shown in figure 5.
Development of a New Microsurgical Robot
467
Fig. 5. Trajectory simulations of the spherical motion mechanism and a biopsy needle.
Conclusion
A prototype of a new microsurgical robot for stereotactic neuro surgery has been designed, and its working space was examined by computer simulation. We are now manufacturing this robot. At the next stage we will develop a control method and examine the perform ance characteristics of the robot. In the future, we expect this robot will be applied to many kinds of neurosurgical operation such as func tional operation, laser treatment, radioactive treatment, etc.
References
2 3
Iseki H, Amano K, Kawamura H, et al: A new apparatus for CT-guided stereotactic surgery. Appl Neurophysiol 1985;48:50-60. Young RF: Application of robotics to stereotactic neurosurgery. Neurol Res 1987: 9:123-128. Kwoh YS: Special stereotactic techniques: Robotic methods applied to stereotactic surgery: in Heibrun MP (ed): Stereotactic Neurosurgery. Baltimore, Williams & Wilkins, 1988. Hiroyuki Koyama, Center of Education and Research, Shibaura Institute of Technology, 307, Fukasaku, Ohmiya-City, Saitama 330 (Japan)
Downloaded by: University of Connecticut 132.174.250.220 - 6/4/2018 8:15:13 AM
1
Development of a New Microsurgical Robot for Stereotactic Neurosurgery Hiroyuki Koyama a , Tateki Uchida3, Hiroyasu Funakuboa , Kintomo Takakurah, Heinz Fankhauser1 J Center of Education and Research, Shibaura Institute of Technology, Saitama: b Department of Neurosurgery, Faculty of Medicine, University of Tokyo, Japan; c Department of Neurosurgery, Universitaire Vaudois, Lausanne, Switzerland
Key Words. Stereotactic surgery • Biopsy • Robot • Microneurosurgery Abstract. The robot technology was introduced into a new stereotactic neurosurg ery system for applications to biopsy, blind surgery, and functional neurosurgery. The authors have developed a newly designed prototype microsurgical robot, designed to allow a biopsy needle to reach the target such as a cerebral tumor within a brain automat ically on the basis of the X, Y, and Z coordinates obtained by CT scanner. This robot is so small that it can be driven in a CT scanner gantry. It consists mainly of the link mech anism and the insertion mechanism. We constructed the link mechanism and investi gated its working space.
Introduction
© I990S. Karger AG. Basel 1011-6125/90/0554-0462 S 2.75/0
Downloaded by: University of Connecticut 132.174.250.220 - 6/4/2018 8:15:13 AM
CT-guided stereotactic surgical procedures, which employ a CT scanner for the localization of the target, have been recently estab lished as the newest technology and are classified into two groups; (1) operation is performed in the operating room after measuring the posi tion of a lesion in a CT room and transporting the patient to the operat ing room, and (2) CT measurements and operation are performed in a CT room [1], For the latter group, several CT-guided stereotactic surg ery systems had been developed. In 1985, Kwoh presented the CTguided stereotactic surgery system which employed an industrial robot (Unimation Puma 200 robot) [2, 3]. Our research relates to the develop-
Development of a New Microsurgical Robot
463
Fig. 1. Block diagram of the CT-guided stereotactic neurosurgery system employing the microsurgical robot.
ment of a new microsurgical robot system for neurosurgery. We de scribe the mechanism and the working space of a new microsurgical ro bot which is computer controlled, so that a biopsy needle can automat ically reach the target within a brain. This robot is characterized by its light weight and small size, so it can be easily attached to an operating table or a CT table.
Construction of the CT-Guided Stereotactic Neurosurgery System
Downloaded by: University of Connecticut 132.174.250.220 - 6/4/2018 8:15:13 AM
The block diagram of our CT-guided stereotactic neurosurgery system is shown in figure 1. The position data of a lesion obtained by a CT scanner are transferred to a personal computer. The three-dimen sional coordinates of the target are calculated by the computer, and then the computer generates control signals for the microsurgical ro bot. The position of the robot is measured with a position-sensitive de vice. The robot is feedback controlled through the computer by using the position data from the position-sensitive device. The position of the biopsy needle within the brain is displayed on the CRT screen.
Koyama/Uchida/Funakubo/Takakura/Fankhauser
464
Design Requirements of the Microsurgical Robot for Stereotactic Neurosurgery
We designed the microsurgical robot in consideration of the fol lowing design requirements: (1) the robot must be small enough to be driven within a CT scanner gantry; (2) the robot is positioned at the upper side of the head (Z axis) when a patient is lying on a CT scanner couch (with a dorsal or ventral position); (3) interference with the sur geon’s maneuvers must be avoided; (4) assuming that the head of a pa tient is a sphere (diameter 200 mm), the tip of the biopsy needle has to reach any position within the sphere; (5) the maximum depth of inser tion is 100 mm; (6) the biopsy needle is inserted into the brain through a burr hole made previously, and (7) the needle is inserted at any angle to the skull to avoid damage to functionally important regions and im portant vascular structures.
Mechanism of the Microsurgical Robot
Our new microsurgical robot consists of two parts. One is the in sertion mechanism which inserts a biopsy needle into the brain at any angle to the skull. The other is a link mechanism which moves the inser tion mechanism at any position on the sphere surface near the patient’s head. The insertion mechanism is attached to the one end of a moving link of the link mechanism.
Link Mechanism for Positioning
Downloaded by: University of Connecticut 132.174.250.220 - 6/4/2018 8:15:13 AM
Generally, three degrees of freedom are required to position the in sertion mechanism at any position near the patient’s head. But, assum ing that the shape of the head is a sphere, only 2 degrees of freedom are required to position the insertion mechanism at any position on a vir tual hemisphere around the head. Therefore, we designed the link mechanism with 2 degrees of freedom which allows the insertion mech anism to be positioned anywhere on the hemisphere. This spherical motion is realized by employing a circular motion mechanism and rotating this circular motion mechanism itself. The circular motion mechanism employing the link mechanism is shown in figure 2. The
Development of a New Microsurgical Robot
465
Fig. 3. Link mechanism.
circular motion mechanism consists of 5 links interconnected by six revolving joints. If we rotate link 5 (DE) around the axis of joint E, the trajectory of one end (Q) of link 2 (BQ) will be a circle. At the same time, if we rotate the whole body of the circular motion mechanism around the axis DE (Z axis), the total trajectory of Q will be a spherical surface. Figure 3 shows a photograph of the link mechanism part.
Insertion Mechanism of a Biopsy Needle
Downloaded by: University of Connecticut 132.174.250.220 - 6/4/2018 8:15:13 AM
We must take into consideration the relative locations of a lesion and a burr hole to design the insertion mechanism. If the burr hole is not perforated on a straight line which passes through the centers of the
Koyama/Uchida/Funakubo/Takakura/Fankhauser
466
virtual sphere and the target, we must rotate the supporting point of the biopsy needle to point the needle toward the target. Therefore, the in sertion mechanism requires two degrees of freedom which allow the bi opsy needle to rotate around two perpendicular axes. Furthermore, one more degree of freedom is required to insert the biopsy needle along the straight trajectory. Totally three degrees of freedom are re quired for the insertion mechanism. The sketch of the insertion mech anism is shown in figure 4.
Working Space of the Microsurgical Robot
Downloaded by: University of Connecticut 132.174.250.220 - 6/4/2018 8:15:13 AM
We examined the working space of our microsurgical robot by computer simulation. The result is shown in Figure 5. The robot can cover one fourth of the virtual sphere. If the diameter of a burr hole is 10 mm, and the distance of the needle-supporting point from the burr hole is 50 mm, the working space of the biopsy needle is inside a cone shown in figure 5.
Development of a New Microsurgical Robot
467
Fig. 5. Trajectory simulations of the spherical motion mechanism and a biopsy needle.
Conclusion
A prototype of a new microsurgical robot for stereotactic neuro surgery has been designed, and its working space was examined by computer simulation. We are now manufacturing this robot. At the next stage we will develop a control method and examine the perform ance characteristics of the robot. In the future, we expect this robot will be applied to many kinds of neurosurgical operation such as func tional operation, laser treatment, radioactive treatment, etc.
References
2 3
Iseki H, Amano K, Kawamura H, et al: A new apparatus for CT-guided stereotactic surgery. Appl Neurophysiol 1985;48:50-60. Young RF: Application of robotics to stereotactic neurosurgery. Neurol Res 1987: 9:123-128. Kwoh YS: Special stereotactic techniques: Robotic methods applied to stereotactic surgery: in Heibrun MP (ed): Stereotactic Neurosurgery. Baltimore, Williams & Wilkins, 1988. Hiroyuki Koyama, Center of Education and Research, Shibaura Institute of Technology, 307, Fukasaku, Ohmiya-City, Saitama 330 (Japan)
Downloaded by: University of Connecticut 132.174.250.220 - 6/4/2018 8:15:13 AM
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