Research On Visualization And Standardization Of Optical Surgical Navigation

Surgical navigation is a multi-disciplinary cutting-edge technology.Surgical navigation system can reduce the uncertainty of surgery and is conducive to the rapid and accurate implementation of surgery.The surgical navigation system can not only help the doctor determine the location of the lesion and set the target point,but also generate the surgical path,assist the doctor to operate the surgical instruments,and clarify the current position and the next step.Visualization technology is used to display the obtained guidance information according to its relative spatial relationship.Standardized techniques for surgical navigation can assess the accuracy of navigation information.Visualization and standardized methods together determine the final clinical performance of surgical navigation.However,surgical navigation visualization currently displays preoperative or intraoperative information to clinicians through twodimensional display devices such as screens,lacking real-time three-dimensional spatial connections with real lesions,and cannot meet the needs of some precise treatment scenarios.In addition,in the acquisition of some lesion data,the nonstandardization of the acquisition instrument greatly weakens the quantification effect of the data,which also limits the value of these data in clinical visualization.Aiming at the key problems in surgical navigation,the work of this paper is mainly divided into the following aspects:1.For the accurate registration of dynamic guidance images and real surgical scenes in the visualization of surgical instruments and surgical paths,the thesis proposes a navigation method based on stereo tracking and Microsoft HoloLens AR glasses,in which the guidance image is the real-time position guidance of surgical instruments.Concrete implementation procedures of the proposed methods are:designing a 3-color LED scalpel tracker and a color-based surgical pose tracking algorithm,using the stereo tracking method to obtain the dynamic guidance of the scalpel and its path,and then designing the registration method of the spatial coordinate system between the system dynamic image-guided space and the real surgical space based on fiducial marker,to realize the accurate position registration of the real surgical space and the dynamic image-guided space.The proposed system can provide dynamic virtual image guidance in medical training and teleguidance surgery.The performance characteristics of the proposed AR telementoring system are verified by benchtop experiments.The clinical applicability of the proposed system in tele-mentored skin grafting surgery and fasciotomy is validated in a New Zealand rabbit model.2.Aiming at the problem of inconsistency of preoperative image guidance caused by tissue deformation in the intraoperative real scene of target lesion visualization,the thesis proposes a near-infrared fluorescence real-time in-situ projection navigation method.The implementation procedures of the proposed method are:using ICG as the contrast agent to mark the target tissue.The in-situ projection system is optically designed to realize real-time acquisition of near-infrared fluorescence images and projection of visible li ght images.Adding structural and optical constraints to make the system imaging and projection light paths parallel to optimize the projection transformation method.Proposing a parallel axis projection correction algorithm based on working distance,which realizes realtime registration between the fluorescence emission site and the projection image,and greatly improves the calculation speed.This method can track the lesion tissue in real time,so as to solve the problem of image-guided space mismatch caused by the dynamic changes of the real scene during surgery.Technical feasibility for projective imaging is verified in an ex vivo model of chicken breast tissue using ICG as a fluorescence agent.Clinical utility for image-guided surgery is demonstrated in a clinical trial where sentinel lymph nodes in breast cancer patients are identified and resected under the guidance of projective imaging.3.Finally,for the lack of standardized test tools for the imaging performance of optical surgical navigation systems,the thesis proposes a method to simulate fluorescence agent with optical phantom system,which can be used for standardized test of fluorescence imaging performance.The specific implementation is as follows:designing the simulation method of the fluorescence excitation efficiency,spatial distribution and emission spectrum characteristics of fluorescent samples so that the fluorescence imaging instrument can have the same response as the real fluorescent agent when imaging the fluorescence luminescence simulation system.The fluorescence excitation efficiency simulation method is that the system controls the intensity of the outgoing simulated fluorescence according to the detected excitation light intensity,and the simulation method of the outgoing fluorescence spatial distribution is achieved by the optical entrance and exit based on the integrating sphere.For fluorescence emission spectrum simulation,a spectral simulation method based on linear filter and liquid crystal display is proposed,and a spectral fitting algorithm based on linear least squares fitting is proposed to automatically simulate arbitrary fluorescence spectra.Compared with traditional fluorescent agents,the fluorescence luminescence simulation system has long-term stable optical parameters.We test the fluorescence imaging sensitivity of different near-infrared fluorescence imaging instruments based on the fluorescent agent simulation system and compare,to preliminarily verify the feasibility of the fluorescence simulation system as a standardized testing tool.In summary,the visualization method of AR navigation based on stereo tracking and fluorescence in-situ projection effectively solves the problem of registration of target lesions,surgical instruments,surgical path image guidance information and surgical space in surgical navigation visualization.The standardized method of the fluorescence simulation system provides a new idea for the standardized test of the imaging performance of the optical surgical navigation system.