Purpose

Most existing robot systems for pedicle screw placement rely on optical markers to establish the spatial relationship between the surgical tool and the surgical path. Marker installation and registration are time-consuming, and error may also accumulate along the complicated coordinate transformation chain. Therefore, we proposed a markerless structured light-based method to simplify the surgery workflow and the coordinate transformation chain.

Methods

Firstly, a structured light camera is used to directly track both the surgical tool and the bone anatomy without using markers. Secondly, a markerless “two-direction” approach for robot-camera registration together with a feedback robot control method is developed. Lastly, a prototype system is built and examined with precision validation experiments and pedicle screw drilling experiments.

Results

Precision validation experiments show satisfactory positioning accuracy of the system. In drilling experiments, 42 paths were drilled on three synthesized cervical vertebrae phantoms and all the paths successfully went through the pedicles. The mean position error of the entry point was 0.28 ± 0.16 mm, and the mean angle error was 0.49 ± 0.24°, which can meet the clinical requirement.

Conclusion

The results show the feasibility of the proposed structured light-based method for pedicle screw placement, which has a simple workflow and can achieve good accuracy without using optical markers.

中文翻译：

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基于结构化光跟踪的无标记机器人椎弓根螺钉放置。

目的

现有的大多数用于椎弓根螺钉放置的机器人系统都依靠光学标记器来建立手术工具和手术路径之间的空间关系。标记器的安装和注册非常耗时，并且错误可能还会在复杂的坐标转换链中累积。因此，我们提出了一种无标记的基于光的方法，以简化手术流程和坐标转换链。

方法

首先，使用结构化的光学相机直接跟踪手术工具和骨骼解剖结构，而无需使用标记。其次，开发了一种无标记的“双向”机器人摄像机配准方法以及反馈机器人控制方法。最后，建立了原型系统，并通过精密验证实验和椎弓根螺钉钻孔实验进行了检查。

结果

精度验证实验表明，该系统具有令人满意的定位精度。在钻孔实验中，在三个合成的颈椎模型上钻了42条路径，所有路径均成功地通过了椎弓根。进入点的平均位置误差为0.28±0.16mm，平均角度误差为0.49±0.24°，可以满足临床要求。

结论

结果表明所提出的基于结构的基于光的椎弓根螺钉放置方法的可行性，该方法具有简单的工作流程并且无需使用光学标记就可以达到良好的精度。