Abstract-Electromagnetic trackers have been used extensively in image-guided surgery and therapy. During the procedure, it is essential to evaluate the effective working range of the tracking system, because the accuracy could be influenced by the environment and manner in which the procedure is conducted. We assume that the guidance is provided by two electromagnetic sensors attached at the distal ends of two endoscopes in order to achieve end-to-end coaptation of the human inner tubular structure. During the procedure, the sensors become very close to help surgeons find the desired path inside the body; as a result, the sensors can potentially cause distortion that adversely affects the accuracy of the tracking system. Thus, it is necessary to determine the working range of the tracking system. The range was evaluated by two methods: static measurement and dynamic measurement. Static measurement determines the range by placing the sensors in several positions and collecting data when the sensors are stationary, whereas dynamic measurement allows movement of the sensors. The experimental results show that these two methods are useful in determining the effective working range.Index Terms-Endoscope, electromagnetic tracking system, interventional guidance.
Surface scanning is able to capture the 3D geometry of patients for follow-up evaluation of surgery. In general, we can use a laser scanner to obtain the 3D image of the surface of the body. Since the surface invisible from the scanner is unable to be captured, it is necessary to capture and register surfaces from several viewpoints. In this situation, the registration is usually time-consuming, because a surface scan consists of large amount of vertices. In this paper, we present a new method to achieve faster registration based on detection of the area with geometric features. The experimental results demonstrate that the proposed method is faster than the conventional method.
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