Mark Points Registration Method In Optical Navigation System Of Radiofrequency Ablation And3D Visualization Research

Radiofrequency ablation is a kind of minimally invasive treatment. Compared to surgicaltreatment, the treatment don’t need to expose surgical lesions which has many advantagesincluding fewer traumas, safety, rapid postoperative recovery, etc. Optical surgical navigationsystem, used in radiofrequency ablation, assists doctors in inserting needle electrode intolesions accurately through real-time positioning of the radiofrequency electrode and improvessurgical efficiency.In order to solve problems of image registration accuracy and efficiency in surgicalnavigation system, the paper proposes marks automatic registration algorithm. Designing akind of markers with higher CT value, then utilizing the image filtering algorithm, thresholdprocessing, and connected region labeling method to extract markers from medical images.Based on the vector of center coordinates of extracting results and model point sets, movingthe markers to make their center locate at the same position. Affine transformation is utilizedto reduce the registration error of the markers and the model point sets. Finally，using iterativeclosest point algorithm(ICP) to optimize the registration results. This registration methodskillfully overcomes shortcomings of ICP that leading to local minima easily.Describing an optical surgical navigation system software applied to radiofrequencyablation, which is the study platform of the markers registration algorithm. In this paper, mainfunction of the software and workflow are described in detail. Combined with the heatconduction equation, the paper simulates the results of radiofrequency ablation in the software.Through volume rendering and surface rendering algorithm, ablation results ofthree-dimensional(3D) visualization get intensive study. By distinguishing the boundarypoints and interior points, the paper measures volume of ablation results effectively.For3D visualization of medical images and observing internal structure of the volumedata, this paper presents an interactive volume data cut algorithm. Transformation between theworld and screen coordinate frames is studied to project voxels of medical data onto thescreen frame and avoid computing intersection of clipping geometry and volumetric data in3D space. For facilitating the decision on whether the voxels should be retained, voxels through coordinate transformation are all projected onto a binary mask image on screen framewhich the closed curve is also projected onto to conveniently obtain the voxels of intersection.The paper pays special attention to optimization algorithm of cutting process. The method ofoctree decomposition is introduced to reduce computation complexity, save computation time,and match real time. The paper presents results obtained from raw and segmented medicalvolume datasets and the process time of cutting operation. The proposed cutting method canarbitrarily clip medical data. To make the cutting tool more flexible and practical, the paperalso researches a regional connectivity extraction, corrosion expansion and other3D volumedata adjustment tool.This paper presents an optical surgical navigation system applied to radiofrequencyablation. In this platform, the paper makes intensive study of markers automatic registrationalgorithm and interactive volume data cut algorithm. The optical surgical navigation systemwith accurate positioning and ease of operation performance will change the status oftraditional minimally invasive treatment and improve the operation efficiency, which is alsothe goal and direction of this study.