Endoscopic Catheter Electromagnetic Positioning And Tracking System

The endoscopes with catheter have been widely used. Since the process to operate the endoscope in the operated target cannot be observed directly, the position and shape of the catheter cannot be estimated, and this affects the operation to the endoscope. For example, when doctor operates the endoscope in clinical, the operation of back and forth to the endoscope would increase pains to patient; what is more, it can also cause medical malpractice. Therefore, there is a need to measure the position and shape of catheter in the operated target and then display the whole catheter to provide for the operator, in order to improve accuracy and quality of the operation.Now, the most popular method is X-ray imaging technology to observe the whole catheter in operation. However, X-ray is a technology with radiation and is harmful to operator, and, the equipment is big, the fee is expensive, it’s inconvenient to use. Therefore, it’s proposed the electromagnetic positioning to the catheter of endoscope in this paper. Electromagnetic positioning has many advantages of high accuracy, no radiation and no occlusion. It can achieve the position and shape of endoscope in real-time, and display the whole shape in monitor to provide for the operator, this can improve the ability to operate the endoscope and upgrade the quality of operation.This paper presents the hardware solution based on the principle of electromagnetic localization, we make generating coils and receiving coils,design the circuit to generate sinusoidal signal and the processing circuit to the inducing signal. We achieve the high precision coupling between the generating coils and receiving coils. According to the principle of electromagnetic induction, we fix the generating coils and arrange the three-axis excitation coils on the catheter. By software algorithms, acquiring parameters about the receiving signal, this paper first propose the method to extract the parameters of the saturated sinusoidal with noises, and enhance the positioning range. Further,we can acquire the positions and orientations of the receiving coils on thecatheter by the process of analytical calculation of the magnetic field strength based on the magnetic dipole model, then reconstructing the shape of the catheter according to those parameters of receiving coils.