Research On Lung Biopsy Needle Positioning System Based On Rectangular Circulation Electromagnetic Positioning

The latest global cancer burden data released by the World Health Organization in 2020 shows that among the new cancer patients in the world,lung cancer has the highest death toll,accounting for 18% of the total deaths,about 1.8 million cases.my country is the country with the largest number of lung cancer patients in the world.Among the new cancer cases in my country in 2020,the incidence and mortality of lung cancer are the highest,accounting for 17.9% and 23.8%,respectively,820,000 cases and 710,000 cases.When a doctor finds a lung mass,pathological testing is the gold standard for diagnosing whether it is lung cancer,and amount of biopsy samples is a prerequisite for high-quality pathological testing.Obtaining a biopsy sample requires a lung puncture operation.At present,doctors mainly judge the location of the lesion based on the patient’s chest CT scan pictures and determine the puncture path and needle entry point based on experience,and then use the biopsy needle to take out the living tissue.The success or failure of lung puncture surgery depends to a large extent on the doctor’s experience.If the biopsy needle does not avoid the large air ducts and blood vessels in the lungs,it will cause complications such as pneumothorax and pulmonary hemorrhage,leading to death of the patient.Moreover,lung puncture operations require patients to undergo 7-8 CT scans.According to a study by the International Commission on Radiological Protection(ICRP),for every additional 1m Sv of X-ray exposure in the human body,the probability of developing malignant tumors will increase by 0.5%.However,multiple CT scans will inevitably cause patients to receive a large amount of X-ray radiation in a short period of time,increasing the risk of cancer.How to locate the trajectory of the puncture biopsy needle,improve the accuracy of puncture,provide doctors with a real-time position reference of the biopsy needle,and reduce the number of CT scans performed on patients and the incidence of complications.This is one of the hot and difficult problems that need to be solved urgently in current puncture operations.One.Canada’s NDI company and American Polhemus company have mature biopsy needle positioning products based on electromagnetic positioning,but they have formed a technical blockade against China,which makes there is no good substitute for domestic products.Therefore,they have developed a lung puncture with independent intellectual property rights.Biopsy needle positioning technology has theoretical significance and practical value.Established the emission magnetic field model based on rectangular circulation according to Pisa’s law,established the mathematical equation of sensor coupling signal and sensor five-degree-of-freedom parameter according to Faraday’s law of electromagnetic induction,solved the relative position of biopsy needle in the positioning system(human body coordinate system),and realized the biopsy needle Dynamic positioning.The main research contents include:(1)Establish the emission magnetic field model based on the rectangular circulation.The magnetic field model of the long straight wire is established by Pisa’s law,and the magnetic field of four orthogonal long straight wires is vector superimposed to construct a single rectangular circulating magnetic field model;on this basis,a transmitting magnetic field model composed of eight coplanar rectangular circulating coils is designed;The establishment of the sensor’s five degrees of freedom and the induced voltage coupling equation can accurately express the biopsy needle pose and reduce the amount of calculation.(2)Design the experimental device of the biopsy needle positioning system.According to the environment of the puncture operation,the movement range and movement posture of the puncture needle were simulated,and an electromagnetic emission plate and a single-layer magnetic core coil sensor based on the rectangular circulating magnetic field model was designed;the technical parameters of the electromagnetic emission plate and the sensor and the signal generator were determined,Signal amplifier,signal acquisition card and technical parameters of DC power supply;using acrylic materials to simulate the puncture operation environment,and build an experimental device based on the rectangular circulation electromagnetic positioning of the lung biopsy needle movement positioning system.(3)A five-degree-of-freedom electromagnetic positioning algorithm for biopsy needles is proposed.The magnetic field information of the magnetic field emission model of the receiving biopsy needle positioning system installed at the end of the biopsy needle is used,and the amplitude and phase of the induced voltage of the eight rectangular circulating magnetic fields on the single-layer magnetic core coil sensor are extracted through asynchronous demodulation;Multiply to calibrate the system and calculate the XYZ coordinate values of the biopsy needle relative to the emitted magnetic field(human body coordinate system),the pitch angle of the central axis relative to the Z axis and the swing angle relative to the Z axis,which are five pose information parameters to determine The specific position and posture of the puncture needle relative to the emitted magnetic field(the axial rotation parameter of the biopsy needle is not involved).Experiments show that the established emission magnetic field model based on the rectangular circulating coil and the proposed five-degree-of-freedom electromagnetic positioning algorithm for the biopsy needle can obtain the fivedegree-of-freedom information of the biopsy needle relative to the emission magnetic field,and realize the positioning of the biopsy needle.