Research On End Positioning Technology Of Surgical Instrument Through Binocular Laser Speckle

Based on MRI and other medical images,the surgical navigation system establishes a precise three-dimensional model of the location of the focus before operation.The three-dimensional model is registered and fused with the anatomical structure around the focus and the location of surgical instruments during operation,so that doctors can clearly observe the location and trajectory of surgical instruments during operation,avoid damaging important nerves and tissues,and make the surgery safer and more accurate.This paper studies the surgical instrument end positioning technology in the surgical navigation system,designs the binocular laser speckle threedimensional measurement system and the surgical instrument positioning target,obtains the three-dimensional point cloud data of the surgical instrument target through the measurement system and processes the point cloud.Two kinds of surgical instrument end positioning technologies are studied: surgical instrument end positioning technology based on geometric parameters of surgical instrument target and surgical instrument end positioning technology based on point cloud registration.1.A binocular laser speckle 3D measurement system is designed.The system measurement model and camera calibration algorithm are studied,and the directional target is used to calibrate the system parameters.A speckle feature point extraction algorithm based on gray value comparison is proposed,which improves the extraction quantity and accuracy.A speckle feature point diffusion matching algorithm combined with descriptor information is proposed.The descriptor information is used to match speckle,which improves the matching quantity and reduces the false matching rate.Newton Raphson(N-R)algorithm is used to solve the sub-pixel coordinates of matching points,and the three-dimensional point cloud data are obtained according to the measurement model.2.The end positioning technology of surgical instruments based on the geometric parameters of instrument targets is studied.European clustering algorithm and RANSAC model fitting algorithm are used to segment surgical instrument targets from complex point cloud environment.According to the design structure of the surgical instrument target,construct the instrument coordinate system,fit the geometric model of the instrument target,and locate the end of the surgical instrument through the geometric parameters of the instrument target.3.The end positioning technology of surgical instruments based on point cloud registration is studied.The principle of surgical instrument calibration and positioning based on point cloud registration method is analyzed.The target point cloud of surgical instrument is roughly registered by principal component analysis(PCA)method to obtain the initial transformation matrix.Through the point to surface iterative closest point(ICP)algorithm for fine registration,improve the accuracy of point cloud registration,obtain an accurate transformation matrix,and realize the end positioning of surgical instruments according to the transformation matrix.