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Published on: May 4, 2022
Navigated bronchoscopy with electromagnetic tracking-cone beam computed tomography influence on tracking and
Håkon Olav Leira1, Erlend Fagertun Hofstad, Lars Eirik Bø
1*Department of Thoracic Medicine, St Olavs Hospital, Trondheim, Norway †Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway ‡Department Medical Technology, SINTEF, Technology and Society, Trondheim, Norway.
Electromagnetic (EM) navigation for bronchoscopy is affected by C-arm fluoroscopy, causing significant tracking errors up to 22 mm. Careful C-arm placement or error correction is crucial for accurate real-time bronchoscopic navigation.
Area of Science:
- Medical imaging
- Medical robotics
- Endoscopic procedures
Background:
- Current image guidance systems for bronchoscopy are limited in scope, primarily for small tumor diagnosis and fiducial placement.
- Advanced bronchoscopic procedures require navigation systems compatible with real-time radiology imaging for control.
- Electromagnetic (EM) field-based navigation systems are common, but their accuracy can be compromised by external equipment.
Purpose of the Study:
- To assess the accuracy of a research navigation platform integrating an EM field generator and a C-arm fluoroscopy unit.
- To evaluate the impact of C-arm fluoroscopy presence within the EM field on navigation accuracy during simulated bronchoscopy.
- To identify sources of error and potential solutions for improving real-time navigation accuracy in bronchoscopy.
Main Methods:
- Simulated a standard bronchoscopy procedure, including image-to-patient registration.
- Introduced a C-arm fluoroscopy unit within the EM field during the simulated bronchoscopy.
- Measured registration accuracy and tracking position errors (wave drift, translation) caused by the C-arm.
Main Results:
- C-arm fluoroscopy significantly influenced registration accuracy, introducing potential errors into the bronchoscopy procedure.
- The C-arm caused wave drift in tracking positions and distorted the EM field, leading to translation errors up to 22 mm.
- A systematic shift in x, y, and z positions was observed even after averaging drift, linked to the fluoroscopy unit's electrical current.
Conclusions:
- A C-arm fluoroscopy unit can be used during EM-guided navigation, but requires careful management to maintain accuracy.
- Errors are primarily associated with the electrical current of the fluoroscopy unit, not solely its metallic structure.
- To ensure real-time navigation accuracy, the C-arm must be positioned outside the EM tracking field or implemented correction schemes are necessary.
