Preliminary Application Of Augmented Reality In Surgical Navigation System Based On Optical Coherence Tomography

As a non-invasive tomography technique,optical coherence tomography,which has high resolution and high sensitivity,has been widely used in medical imaging.At present,OCT technology is mostly used in ophthalmology.It can not only show macroscopic structures such as cornea,iris and sclera,but also provide images of micro structures such as trabecular meshwork,optic chiasm and Schlemm's canal.OCT has become an important assistant tool for the diagnosis and treatment of ophthalmic diseases.Based on the OCT three-dimensional model,which are collected and reconstructed pre-operatively,and intraoperative real-time OCT two-dimensional slice images,surgeons can plan surgery route,judge the condition of tissues,get real-time navigation,and evaluate the effect of surgery,which can reduce surgical trauma and shorten the operation time.OCT technology has become an indispensable part in the navigation of ophthalmic surgery.In research and clinical applications,providing microscopic images of the surgical area,two-dimensional OCT slice images and three-dimensional OCT models makes the spatial location and tissue structure of the lesion more intuitive.However,the twodimensional and three-dimensional information provided by the OCT surgical navigation system still need to be registered by surgeons.Surgeons need to observe the OCT image and microscopic image at the same time,which requires a wealth of surgery experience,rich imagination and long-term systematic learning.Limitation above has undoubtedly added some resistance to the development and application of OCT navigation system.Augmented reality(AR)technology can solve the registration problem between different modality images.In this thesis,the ray-casting algorithm is firstly used to reconstruct OCT volume data to provide different modality image inputs;then the guiding source is used to obtain the fiducials in the different modality images,and the improved Zhang's calibration method is used to navigate the the camera of OCT navigation system;finally,the microscopic image is registered with the OCT three-dimensional model through affine transformation and direct fusion.The superimposed images can effectively integrate the two-dimensional and three-dimensional information of the operation area,enhance the doctor's perception of the depth information of the lesion,and bring great convenience to the preoperative surgery planning,intraoperative real-time navigation and postoperative effect evaluation.In terms of experiments,we conducted in vitro and in vivo imaging experiments on model eyes and animal eyes using the mentioned registration method.We have obtained a two-dimensional registration image containing the physiological information and depth structure information of the scanned area,and the registration error is about 0.04 mm,which satisfies the requirement of ophthalmology surgery.The registration method can meet the needs of surgical navigation initially.