School of Mechanical Engineering, Tianjin University, Tianjin, 300350, China.
Centre for advanced Mechanisms and Robotics, Tianjin University, Tianjin, 300350, China.
Med Phys. 2017 Sep;44(9):4828-4837. doi: 10.1002/mp.12435. Epub 2017 Jul 28.
Currently, lung brachytherapy in clinical setting is a complex procedure. Operation accuracy depends on accurate positioning of the template; however, it is difficult to guarantee the positioning accuracy manually. Application of robotic-assisted systems can simplify the procedure and improve the manual positioning accuracy. Therefore, a novel CT-guided robotic system was developed to assist the lung cancer brachytherapy.
A four degree-of-freedom (DOF) robot, controlled by a lung brachytherapy treatment planning system (TPS) software, was designed and manufactured to assist the template positioning. Target position of the template can be obtained from the treatment plan, thus the robot is driven to the target position automatically. The robotic system was validated in both the laboratory and the CT environment. In laboratory environment, a 3D laser tracker and an inertial measurement unit (IMU) were used to measure the mechanical accuracy in air, which includes positioning accuracy and position repeatability. Working reliability was also validated in this procedure by observing the response reliability and calculating the position repeatability. Imaging artifacts and accuracy of the robot registration were validated in the CT environment by using an artificial phantom with fiducial markers. CT images were obtained and used to test the image artifact and calculate the registration accuracy. Phantom experiments were conducted to test the accuracy of needle insertion by using a transparent hydrogel phantom with a high imitation artificial phantom. Also, the efficiency was validated in this procedure by comparing time costs in manual positioning with robotic positioning under the same experimental conditions.
The robotic system achieved the positioning accuracy of 0.28 ± 0.25 mm and the position repeatability of 0.09 ± 0.11 mm. Experimental results showed that the robot was CT-compatible and responded reliably to the control commands. The mean registration accuracy of the robotic system was 0.49 ± 0.29 mm. Phantom experiments indicated that the accuracy of needle insertion was 1.5 ± 1.7 mm at a depth ranging from 30 to 80 mm. The time used to adjust the template to the target position was 12 min on average by robotic system automatically. An average of 30 min was saved compared with the manual positioning procedure in phantom experiments.
This paper describes the design and experimental validation of a novel CT-guided robotic system for lung cancer brachytherapy. The robotic system was validated in a number of aspects which prove that it was capable of locating the template with clinically acceptable accuracy in the CT environment. All experimental results indicated that the system is reliable and ready to be applied to further studies on animals.
目前，临床中的肺部近距离放射治疗是一个复杂的过程。操作的准确性取决于模板的精确定位；然而，手动很难保证定位精度。机器人辅助系统的应用可以简化该过程并提高手动定位精度。因此，开发了一种新型 CT 引导机器人系统来辅助肺癌近距离放射治疗。
设计并制造了一个四自由度（DOF）机器人，由肺部近距离放射治疗计划系统（TPS）软件控制，以协助模板定位。可以从治疗计划中获得模板的目标位置，从而自动驱动机器人到达目标位置。在实验室和 CT 环境中对机器人系统进行了验证。在实验室环境中，使用 3D 激光跟踪仪和惯性测量单元（IMU）来测量空气中的机械精度，包括定位精度和位置重复性。在此过程中，通过观察响应可靠性并计算位置重复性来验证工作可靠性。通过使用带有基准标记的人工模型在 CT 环境中验证机器人的配准成像伪影和准确性。获得 CT 图像并用于测试图像伪影并计算配准精度。通过使用具有高模仿人工模型的透明水凝胶模型在透明水凝胶模型中进行针插入实验，验证了准确性。此外，通过在相同的实验条件下比较手动定位和机器人定位的时间成本，验证了效率。
机器人系统实现了 0.28±0.25mm 的定位精度和 0.09±0.11mm 的位置重复性。实验结果表明，机器人与 CT 兼容，对控制命令可靠响应。机器人系统的平均注册精度为 0.49±0.29mm。在模型实验中，针插入的精度在 30 至 80mm 的深度范围内为 1.5±1.7mm。通过机器人系统自动调整模板到目标位置的平均时间为 12 分钟。在模型实验中，与手动定位过程相比，平均节省了 30 分钟。
本文描述了一种新型 CT 引导机器人系统用于肺癌近距离放射治疗的设计和实验验证。该机器人系统在多个方面进行了验证，证明它能够在 CT 环境中以临床可接受的精度定位模板。所有实验结果表明，该系统是可靠的，并准备好进一步应用于动物研究。
