基于惯性导航与电磁导航融合的靶器官运动跟踪方法研究

Research on target organ motion tracking method based on the fusion of inertial navigation and electromagnetic navigation

靶器官的术中运动是目前制约临床手术中尤其是放射性治疗手术诊疗效果的关键难点问题。其非预期姿态变化会导致术中目标靶区的偏离,从而影响治疗效果甚至引发严重并发症等。因此有必要对术中靶器官的运动进行实时精准的位姿跟踪,以提高手术治疗效果与安全性。提出一种基于惯性导航与电磁导航融合的术中靶器官运动融合跟踪方法,可利用人体自然腔道在无创或微创条件下对靶器官运动进行直接测量。基于所提出的融合跟踪系统干扰状态判别方法,利用扩展卡尔曼滤波器对惯性测量单元与电磁定位信息融合,实现在不同干扰情况下的靶器官运动融合跟踪,有效提高术中器官跟踪的实时性与鲁棒性。同时基于0.002 rad/s陀螺仪,5 mg加速度计及6自由度电磁定位系统,研制了导管式靶器官融合跟踪器,并在模拟术中电磁干扰环境下进行了动态与静态验证实验。通过实验得到在受到严重电磁扰动情况下其位移与姿态的最大跟踪误差分别为2.51 mm和0.127 rad。在非电磁干扰条件下,其位移与姿态最大跟踪误差分别为0.93 mm和0.011 rad。结果证明基于惯性导航与电磁导航融合的靶器官术中跟踪方法可行,且能够在临床许可误差范围内实现对术中靶器官的运动位姿进行跟踪测量。

The intraoperative movement of target organs is currently a key and difficult problem that restricts the diagnosis and treatment of clinical surgery, especially radiotherapy. The unexpected posture changes can cause the deviation of the target area during operation, thereby affecting the treatment effect and even causing serious complications. Therefore, it is necessary to track the movement of target organs in real time and accurately improve the effect and safety of surgical treatment. This paper proposes a target organ movement fusion tracking method based on inertial navigation and electromagnetic navigation fusion, which can directly measure the movement of the target organ under non-invasive or minimally invasive conditions using the human natural cavity. Based on the proposed interference state discriminating method of the fusion tracking system, the extended Kalman filter is used to fuse the inertial measurement unit and the electromagnetic positioning information and realize the fusion tracking of the target organ movement under different interference conditions, which effectively improves the real-time performance and robustness of intraoperative organ tracking. At the same time, based on a 0.002 rad/s gyroscope, a 5 mg accelerometer and a 6-DOF electromagnetic positioning system, a catheter-type target organ fusion tracker was developed, and dynamic and static verification experiments were carried out in a simulated intraoperative electromagnetic interference environment. Through experiments, the maximum tracking errors of displacement and attitude are 2.51 mm and 0.127 rad, respectively under severe electromagnetic disturbance. Under non-electromagnetic interference condition, the maximum tracking errors of displacement and attitude are 0.93 mm and 0.011 rad, respectively. The results prove that the target organ tracking method based on the fusion of inertial navigation and electromagnetic navigation is feasible, and can realize the tracking and measurement of the target organ movement posture within the clinical permission error range.