用于微创手术导航的六自由度电磁跟踪方法

Six Degree-of-freedom Electromagnetic Tracking Method for Navigation of Minimal Invasive Operation

目的为在微创手术中确定体内器械的位置和方向,提出一种不依赖磁场模型电磁跟踪方法。方法采用体外2根可在三维空间旋转的磁棒,利用磁场最大值搜索体内微型正交三轴磁场传感器以确定其位置,进而依据磁棒轴线上磁场方向特点,利用坐标系旋转关系确定传感器的空间姿态。我们对系统的误差和跟踪特性进行了仿真,并设计了实验原型进行验证。结果初步的实验结果表明,在40 cm范围内系统平均的位置和方向误差分别为1.387 cm和5.023°。仿真结果还表明,若进行精确参数测量,系统可以达到更加理想的精度。结论本方法能够满足微创手术导航的要求,且算法简单可靠,有良好的应用前景。

Objective By using non-iterative algorithm,to propose and verify a novel non-model-based electromagnetic method for tracking the position and orientation of instruments inside the human body during the minimal invasive operation.Methods The proposed method was realized by rotating 2 coils outside human body to search for the position of a minimal 3-axis orthogonal magnetic sensor inside body,with maximal magnetic flux density.The orientation of the sensor could be calculated from the relationship between the coordinate frame of the sensor and that of the coils based on the direction of magnetic flux densities along the axis of the coils.The simulation experiment was used to evaluate the error performance and the tracking performance of the system.Then the real performance of the method was evaluated by in vitro experiments.Results Experimental results showed that the averaged position error was 1.387 cm and the averaged orientation error was 5.023° within the tracking region of 40 cm.It was also shown from the simulation that a higher resolution might be obtained.Conclusion Therefore,the proposed method can effectively satisfy the requirement of the navigation in the minimally invasive operation with a simple algorithm and thus has a good prospect in application.