Research On Key Technology For Image Guided Spine Surgery And Development Of Application System

Spine surgery is considered as a common yet risky surgical treatment. Before the Image-guided surgery (IGS) technology was introduced, the surgeons could only rely on the anatomical information obtained from the preoperative CT images or inoperative X-ray fluoroscopes which can only offer limited help for the surgeons in terms of reconstruction of the 3D image of the patients. The quality of the surgery mainly reckons on the surgeons' experiences. Besides, X-ray Fluoroscopy during the surgery increases the radiation exposure to both the patients and the surgeons. To obtain different views, it necessary to reposition the C-arm X-ray machine, prolongs the operating time and increases the infection risks. IGS technology is aimed to solve these problems. Based on medical image data and with the help of virtual reality technology, IGS uses dimensional position sensor to track the medical instruments and the pathological tissue and to correlate the operative field to the preoperative medical imaging data and leads to the real time guide during the surgery. IGS provides important clinic value in improving surgical positioning precision, lowering surgical trauma and error rate and has become one of the most important research directions in computer-aided therapy field.The goal of this dissertation is to implement IGS system for spine surgery by solving the key technologies. Based on imaging modality, we focus on three different image guided systems, which are based on fluoroscopy image, CT image and 3D/2D imaging registration respectively.1. X-ray fluoroscopy based IGSWe increase image definition by restoring fluoroscopy images using a modified Wiener filter and wavelet synthetic filter. Then, we improve the calibration algorithm for the C-arm fluoroscopy image system, propose an "on line" calibration technique and revise the image distortion caused by the image intensifier. This technology eliminates the disadvantage caused by the image distortion, shortens the preparation time before surgery and improves the flexibility of the C-arm X-ray machine. Finally, we develop a system of X-ray fluoroscopy based IGS combined with coordinate transform.2. CT image based 3D IGSWe mainly focus on two problems. First, we use a texture mapping-rendering algorithm to accelerate the 3D images reconstruction. Second, we propose a registration method combing of point matching and surface matching registration method. We also modify the Iterative Closest Point (ICP) algorithm to register the surface of bony structures of CT to patient, which increases the precision and efficiency of the IGS proceeding. Applying above technologies, we develop a system of CT image based IGS.3. 3D/2D images registration based mini invasive IGSMinimal invasive surgery is the future of spine surgery and brings new challenge to IGS. We present a novel multi-step 3D/2D images registration method. After using point and surface feature based registration method for coarse registration, we use an improved gradient feature based registration method for fine registration. This gradient feature based method provides a feasible way of determining the global solution. Besides, the speed of registration is greatly accelerated since this method only samples the rays passing through the edge of X-ray image.Further experiment is performed using a lumbar spine phantom to evaluate our IGS system. We have tested the registration error, location error, preparation time and other indicators. The test result demonstrates that our IGS system has met with the clinical application standard after comparing our data with the similar products abroad.Finally, we develop a IGS system for clinical spine surgery after integrating hardware and software.