胶囊内窥镜跟踪系统的可调式磁场发生装置的设计

Design of Adjustable Magnetic Field Generating Device in the Capsule Endoscope Tracking System

胶囊内窥镜由口腔进入消化道,可弥补传统检测的盲区,然而诊查医生无法将诊查信息与诊查部位对应,因此需要对胶囊内窥镜在体内的方位实现跟踪。本研究提出了交流励磁式胶囊内窥镜无线跟踪方法,由胶囊内的磁场传感器检测体外励磁线圈产生的磁场,通过求解磁场逆问题可获得胶囊内窥镜的方位。由于磁场随距离的三次方衰减,导致接收信号的动态范围跨度三个数量级,由此设计开发了体外可调式交变磁场发生装置,通过磁场传感器所反馈的磁场信号,自动调节产生的交变磁场强度。由样机实验可知:可调式磁场发生装置正确可行,成功实现了磁场强度的自动调节,由此改善了磁场传感器的信噪比,从而提高了跟踪精度。

The capsule endoscope swallowed from the mouth into the digestive system can capture the images of important gastrointestinal tract regions. It can compensate for the blind spot of traditional endoscopic techniques. It enables inspection of the digestive system without discomfort or need for sedation. However, currently available clinical capsule endoscope has some limitations such as the diagnostic information being not able to correspond to the orientation in the body, since the doctor is unable to control the capsule motion and orientation. To solve the problem, it is significant to track the position and orientation of the capsule in the human body. This study presents an AC excitation wireless tracking method in the capsule endoscope, and the sensor embedded in the capsule can measure the mag- netic field generated by excitation coil. And then the position and orientation of the capsule can be obtained by solving a magnetic field inverse problem. Since the magnetic field decays with distance dramatically, the dynamic range of the received signal spans three orders of magnitude, we designed an adjustable alternating magnetic field generating de vice. The device can adjust the strength of the alternating magnetic field automatically through the feedback signal from the sensor. The prototype experiment showed that the adjustable magnetic field generating device was feasible. It could realize the automatic adjustment of the magnetic field strength successfully, and improve the tracking accuracy.