Research On Key Technologies Of Orbital Endoscopic Surgical Navigation System

The orbital surgery is one of the most complex surgeries, the orbital anatomical structure contains eye, optic nerves, blood vessels, extraocular muscles and other important structures. It is the high-risk surgery, offen cause irreparable consequences. It requires high precision to reset orbital fractures and reconstruct visual function. Therefore, the international development of orbital surgery is minimally invasive and accurate. The endoscopic technology allows minimally invasive surgery, and image guided surgical navigation technology can improve the precision of surgery. So, the combination of surgical navigation and endoscopic technique can improve the accuracy , security and minimally invasive of orbital operation. But in our nation, there is not develop the orbital endoscopic surgical navigation system yet. Because of the limitations of the traditional surgical treatment of orbital endoscopic surgery, we developed the orbital endoscopic surgical navigation system. The detailed studies include:1. The problem of medical image processing and three-dimensional reconstruction. In image processing, through the comparision of some common methods of spatial filtering and image segmentation, we used the median filtering method to denoise CT image and combine the method of threshold and region growing to segment bone tissues. Based on the improved Marching Cubes algorithm, we realized the three-dimensional reconstruction of skull. At last, we used the quadric error metric method to simplify original model.2. The coordinate system conversion of surgical navigation system. For the coordinate conversion problem of patients and surgical instruments, we used quaternion to express the location of spatial coordinate system, derived the quaternion expression of spatial coordinate system and synthesis quaternion expression of the rotation between different coordinate systems. We also using spherical linear interpolation method to achieve the smooth transition of surgical instruments in the three-dimensional model coordinate system.3. The problem of spatial registration. We discussed the different methods of surgical navigation systems, using human anatomical landmarks and character surface to achieve registreation. The registration process is divided into two parts, the first part is initial registration which is based on human anatomical landmarks and the second part is fine registration which is based on human character surface. This method not only reduces the trauma to patients , but also improves the registration accuracy and registration rate.4. The problem of endoscopic surgical navigation system integration. We developed the endoscopic video acquisition system based on the DirectShow technology, and realized the integration of endoscopic surgical navigation system. We also discussed the design method of passive tool, and verified the registration accuracy and real-time tracking accuracy of endoscopic surgical navigation system by model experiment.