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

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. © 2020, Science Press. All right reserved.