Unified Assessment of Electromagnetic tracking Systems

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Supervisor:
Dr. Haidegger Tamás Péter
Department of Control Engineering and Information Technology

Medical technology and devices have shown an incredible development in the past decades. Computer Integrated Surgery (CIS) revolutionized the interventional medicine. Image-Guided Surgery (IGS) was particularly well received in neurosurgery, orthopedics and cardiology surgery. By using surgical navigation systems, it has become possible to visualize the patient's pre- and intra-operative records of the desired region in real time.

The most often employed tracking systems are the optical trackers, but the using of electromagnetic surgical navigation systems (EMTS) is spreading worldwide, because they don't require full line-of-sight in the navigation. The position and orientation of tiny sensors can be determined with sub-millimeter accuracy in the field created by the EM generator.

While EMT has many advantages, the distortion of the field caused by conductive or ferromagnetic materials (laparoscopic tools, metal trays, operating table, etc.) and other electronic devices may be the source of significant reduction in performance. Hereby the accuracy and reliability of these systems can be able to increase. The research community has long been engaged with the topic to find engineering solutions to increase measurement reliability and accuracy. To this end, the defination and modelling of the system errors and the determination of different surgical tool’s distortion are necesarry.

This diploma thesis gives a comprehensive overview of the operation principle of different electromagnetic tracking system’s , its typical accuracy and errors.

I introduce the emerging errors during the precision and calibration measurements. I detail the results of the different tracker’s accuracy examination and I do the validation of the used measurement protocol. After the data evaluation, I perform the statistical analisys of the results. It permit of determine the distribution of the errors. Finally, I make an attemt to develop a new measurement protocol and I execute the reproducibility measurements.

The main principal of my work was the development and validation of a widely usable method for the electromagnetic tracker’s spatial accuracy assessment, with a specific goal to determine the most relevant sources of errors and distortions.

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