Purpose

Radioactive seed implantation is an effective invasive treatment method for malignant liver tumors in hepatocellular carcinomas. However, challenges of the manual procedure may degrade the efficacy of the technique, such as the high accuracy requirement and radiation exposure to the surgeons. This paper aims to develop a robotic system and its control methods for assisting surgeons on the treatment.

Method

We present an interventional robotic system, which consists of a 5 Degree-of-Freedom (DoF) positioning robotic arm (a 3-DoF translational joint and a 2-DoF revolute joint) and a needle actuator used for needle insertion and radioactive seeds implantation. Control strategy is designed for the system to ensure the safety of the motion. In the designed framework, an artificial potential field (APF)-based motion planning and an ultrasound (US) image-based contacting methods are proposed for the control.

Result

Experiments were performed to evaluate position and orientation accuracy as well as validate the motion planning procedure of the system. The mean and standard deviation of targeting error is 0.69 mm and 0.33 mm, respectively. Needle placement accuracy is 1.10 mm by mean. The feasibility of the control strategy, including path planning and the contacting methods, is demonstrated by simulation and experiments based on an abdominal phantom.

Conclusion

This paper presents a robotic system with force and US image feedback in assisting surgeons performing brachytherapy on liver tumors. The proposed robotic system is capable of executing an accurate needle insertion task with by optical tracking. The proposed methods improve the safety of the robot’s motion and automate the process of US probe contacting under the feedback of US-image.

中文翻译：

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用于肝肿瘤近距离放射治疗的新型多自由度手术机器人系统：设计和控制

目的

放射性种子植入是治疗肝细胞癌恶性肝肿瘤的一种有效的侵入性治疗方法。但是，手动操作的挑战可能会降低该技术的效率，例如对准确性的要求高以及对医生的放射线照射。本文旨在开发一种机器人系统及其控制方法，以协助外科医生进行治疗。

方法

我们介绍了一种介入式机器人系统，该系统由一个5自由度（DoF）定位机械臂（一个3 DoF平移关节和一个2 DoF旋转关节）以及一个用于针头插入和放射性种子植入的针头致动器组成。 。为系统设计了控制策略，以确保运动的安全性。在设计框架中，提出了基于人工势场（APF）的运动计划和基于超声（US）图像的接触方法进行控制。

结果

进行了实验，以评估位置和方向的准确性，并验证系统的运动计划程序。瞄准误差的平均值和标准偏差分别为0.69 mm和0.33 mm。平均机针放置精度为1.10毫米。通过基于腹部模型的仿真和实验证明了控制策略的可行性，包括路径规划和接触方法。

结论

本文介绍了一种具有力和US图像反馈的机器人系统，可协助外科医生对肝脏肿瘤进行近距离放射治疗。所提出的机器人系统能够通过光学跟踪来执行精确的针头插入任务。所提出的方法提高了机器人运动的安全性，并在US图像的反馈下自动进行US探针的接触过程。