Clinical use of a robot with an automatic chasing capability of the target for MR image guided surgery

本研究项目的目的是利用便携式机器人在临床笼子中进行磁共振图像引导下的微波消融治疗肝脏肿瘤。我们开发了一种MR兼容的机器人，它具有2个光学角度传感器和3个超声波电机，利用运动中心远程约束自动追逐预定的目标点。该机器人在强磁场中正常工作，即使在超声波电机运动过程中也不会干扰磁共振成像。在虚拟针长为15 cm的情况下，机器人控制的图像中心位置误差小于2 nUN。为了临床使用，在手机角度传感器的光纤上制备了连接器。因此，末端效应器可以与用于杀菌的主要部件分开。为了患者的安全，在机器人的垂直杆上准备了一个由铰链和楔子组成的机械保险丝。当对手臂的力超过预设阈值时，关节将被释放，手臂将上升。还增加了棘轮机构，以保持机械臂处于提升位置。在这种情况下，机械臂不能物理接触病人。还准备了一个电气关闭开关，以增加安全机制。我校伦理委员会批准了该机器人的临床应用。在清除安全问题后，对志愿者进行了反复的模拟研究。并针对临床应用对导航软件进行了优化。最后，该机器人在2例临床病例中应用于磁共振引导下的肝肿瘤微波消融。手术顺利安全地完成，机器人在这一手术中的协助被证明是有用的。

The objective of this research project is the utilization of a portable robot for MR-image-guided microwave ablation of liver tumors in clinical cages. We have developed an MR-compatible robot having 2 optical angle sensors and 3 ultrasonic motors, which automatically chases the predefined target point using remote-center-of-motion constraint. This robot properly worked in the strong magnetic field and did not interfere with MR imaging even during the movement of the ultrasonic motors. The error of the image center position controlled by the robot was less than 2 nun with a virtual needle length of 15 cm. For clinical use, connecters were prepared on the optic fiber of the angle sensors of the hand-piece. Accordingly, the end effecter could be separated from the main parts for the sterilization. For the safety of patients, a mechanical fuse, consisting of a hinge and wedge, was prepared on the vertical pole of the robot. The joint was released and the arm went up when the force to the arm exceeded the preset threshold. A ratchet mechanism was also added to keep the robot arm at the lifted position. In this situation, robot arm could not physically touch the patient. An electrical shut-down switch was also prepared for additional safety mechanism. The Ethics Committee of our university approved the clinical use of this robot. After the clearance of safety issue, simulation studies were repeatedly conducted with volunteers. and navigation software was optimized for the clinical use. Finally this robot was used in 2 clinical cases for MR guided microwave ablation of liver tumors. The procedures were successfully and safely accomplished, and the robot assistance in this procedure was found to be useful.