Design And Experimental Research On A CT Image Guided Surgical Robotic System For Lung Cancer Brachytherapy

This paper focus on the development of a Computed Tomography(CT)guided surgical robotic system for lung cancer brachytherapy.Based on the clinical operation requirements and work conditions,the robot mechanism and control system was design.The robotic system was manufactured and the position accuracy was validated both in the laboratory and the CT environment.The main contents and research achievements are as following:Firstly,a 4 degree-of-freedom(DOF)serial robot was designed based on the clinical procedure requirements.In order to achieve large enough workspace and compact mechanism,arc guide rail was used and the robot can be installed on the either side of the CT table flexible.Robot shell was designed to fit the medical environment.Also,the manufacture and assembly work was completed.Secondly,the registration method was designed to solve the positioning between the robot and CT image space.To validate the workspace and achieve point to point control,the kinematic analysis was calculated based on D-H method.The workspace was plotted by using forward kinematics and the point to point control was achieved by the inverse kinematics model.Thirdly,the embedded motion control system based on ARM was designed according to the control requirements which includes hardware and software design.The schematic circuit diagram drawing and printed circuit board design was completed in the hardware design and the circuit board has been debugged.The programming of the micro controller unit(MCU)was completed in the software design and the communication between the control board and the treatment planning system(TPS)was achieved by a RS485 bus.Also,the whole system debugging was completed based on above work.Finally,the accuracy validation of the robotic system was conducted in laboratory and CT environment.In laboratory,the positioning accuracy was 0.28 mm and the position repeatability was 0.09 mm which measured by laser tracker and inertial measurement unit(IMU).In CT environment,the robot response reliable to control commands and it was CT compatible.Through three-dimensional reconstruction and measuring all the CT images,the registration accuracy was 0.49 mm.The accuracy of needle insertion was 1.5mm in a hydrogel phantom which achieved the desire accuracy of less than 2 mm.The clinical experiments validate the accuracy of seeds implantation.