Medical Tool Localization with Hall-Effect Sensors in Electromagnetic Navigation Systems
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Embargoed until 2026-05-13
Author
Date
2024Type
- Doctoral Thesis
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Abstract
Remote magnetic navigation (RMN) offers a wide range of possibilities, particularly in the realm of minimally invasive interventions. With the increased dexterity and precise catheter tip control of magnetically actuated medical devices, surgeons can navigate more complex environments. However, in minimally invasive surgeries, the need for tool visualization feedback is essential.
Fluoroscopy has long been the gold standard for visualizing tools during interventions using magnetic navigation systems (MNS). While it offers high accuracy and flexibility for catheter tracking, its use of ionizing radiation raises concerns for both medical staff and patients. As a result, research has been dedicated to minimizing fluoroscopy exposure and exploring non-ionizing tracking alternatives. Nevertheless, these alternatives often come with high costs and compatibility issues with magnetic navigation.
While the primary function of MNS is the control and actuation of magnetic devices, this thesis explores their localization potential using Hall-effect sensors to measure the magnetic fields generated and estimating their positions. These sensors are cheap, reliable, and widely accessible. In recent years, they have undergone substantial advancements, shrinking in size while maintaining or enhancing measurement capabilities. This makes them an optimal choice as a cost-effective alternative to other tracking modalities.
The thesis explores the triangulation method that leverages multiple field sources to generate signals for localizing a sensor within the system’s workspace. It discusses key factors impacting localization performance, error sources, and system properties, considering both direct and alternating current implementations.
A gradiometer-based tool localization is introduced. This method relies on a fixed sensor array to approximate the magnetic gradient, collecting additional information about the magnetic field to enable single-measurement localization.
The research investigates autonomous localization and navigation of catheters in constrained environments, leveraging feedback from a single Hall-effect sensor. This approach is valuable in surgical interventions where pre-operative vasculature information is available, narrowing the search space for the localization algorithm and optimizing magnetic gradients for real-time tracking.
Lastly, the thesis addresses the need for more than just tip position information in continuum robot navigation. It presents a method for continuous shape reconstruction in catheters equipped with multiple Hall sensors. This approach combines measurements of magnetic fields with a kinematic model of the catheter, offering real-time shape reconstruction using DC magnetic fields.
In summary, the methods explored in this thesis reveal the localization potential of magnetic navigation systems. By utilizing Hall-sensor based approaches, the research offers an alternative tracking modality that may reduce radiation exposure during RMN interventions. Furthermore, these findings extend the capabilities of magnetic navigation systems, contributing to their advancement and acceptance within the medical field. Show more
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https://doi.org/10.3929/ethz-b-000672475Publication status
publishedExternal links
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Publisher
ETH ZurichSubject
Magnetic localization; Catheter tracking; continuum robots; magnetic actuation; magnetic navigation systems; Hall-effect sensorOrganisational unit
03627 - Nelson, Bradley J. / Nelson, Bradley J.
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ETH Bibliography
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