[Accuracy analysis of robotic assistant needle placement for trigeminal gasserian ganglion].

objectiveTo evaluate the accuracy and feasibility of a custom robot system guided by optical navigation for needle puncture on trigeminal gasserian ganglion.

methodsA synthetic human skull model was used, with plasticine placed around the skull base to imitate the human soft tissue. Cone beam CT (CBCT) scanning was performed before the operation. With image data transferred to the graphical user interface of the computer workstation, the oval foramen was selected as the target and the "skin entry point" was also determined by the surgeon on the surgical planning software. Thus the needle trajectory was eventually planned. The skull model was fixed firmly to the trial table with a head clamp and relative size of the trial table was the same as a standard operating table. Following point-based registration, the data were sent to the robot control unit. Only after the surgeon's confirmation, the needle was automatically inserted into the intended target by the robot guided by optical navigation. When the procedure was completed, the instantaneous data of the needle tip orientation acquired by navigation system was sent back to the computer workstation for accuracy verification by calculating the geometric distance between the needle tip and the planning target after matrix transformation. Subsequently, after the needle had been released, CBCT scanning was also acquired to make image fusion of the preoperative skull and the postoperative skull. The data of the needle tip orientation was acquired on the postoperative image and the accuracy was re-verified by calculating the geometric distance between the needle tip and the planning target after matrix transformation. IBM SPSS Statistics 20 was used for statistical analysis and the paired t-test was used to compare the differences in the accuracy measured by the intraoperative navigation and postoperative image fusion.

resultsAll 20 interventions were successfully located in oval foramen at the first needle insertion. The mean deviation of the needle tip was (0.56±0.07) mm (measured by the navigation system) and (1.49±0.14) mm (measured by the image fusion), respectively (P<0.001).

conclusionThe experimental results show the robot system is efficient and reliable. The navigation accuracy is one of the most significant factors in robotic procedures.