Electromagnetic tracking in surgical and interventional environments: usability study

Lugez, Elodie; Sadjadi, H. Mohseni; Pichora, David R.; Ellis, Randy E.; Akl, Selim G.; Fichtinger, Gabor

doi:10.1007/s11548-014-1110-0

Cited by 55 publications

(35 citation statements)

References 35 publications

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“…In general, the measurement errors have nonuniform distributions over the tracking volume [22]. It is therefore necessary to characterize systematic (bias) and random (jitter) errors, in terms of both position and orientation of the sensor.…”

Section: ) Error Parametersmentioning

confidence: 99%

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Simultaneous Electromagnetic Tracking and Calibration for Dynamic Field Distortion Compensation

Sadjadi

Hashtrudi-Zaad

Fichtinger

2016

IEEE Trans. Biomed. Eng.

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Electromagnetic (EM) tracking systems are highly susceptible to field distortion. The interference can cause measurement errors up to a few centimeters in clinical environments, which limits the reliability of these systems. Unless corrected for, this measurement error imperils the success of clinical procedures. It is therefore fundamental to dynamically calibrate EM tracking systems and compensate for measurement error caused by field distorting objects commonly present in clinical environments. We propose to combine a motion model with observations of redundant EM sensors and compensate for field distortions in real time. We employ a simultaneous localization and mapping technique to accurately estimate the pose of the tracked instrument while creating the field distortion map. We conducted experiments with six degrees-of-freedom motions in the presence of field distorting objects in research and clinical environments. We applied our approach to improve the EM tracking accuracy and compared our results to a conventional sensor fusion technique. Using our approach, the maximum tracking error was reduced by 67% for position measurements and by 64% for orientation measurements. Currently, clinical applications of EM trackers are hampered by the adverse distortion effects. Our approach introduces a novel method for dynamic field distortion compensation, independent from preoperative calibrations or external tracking devices, and enables reliable EM navigation for potential applications.

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Section: ) Error Parametersmentioning

confidence: 99%

“…The ground truth optical tracking observations are then used to determine the tracking error at each location. Alternatively, error characterization could be performed with manual positioning [23], or a calibration phantom [22].…”

Section: ) Error Parametersmentioning

confidence: 99%

Simultaneous Electromagnetic Tracking and Calibration for Dynamic Field Distortion Compensation

Sadjadi

Hashtrudi-Zaad

Fichtinger

2016

IEEE Trans. Biomed. Eng.

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“…This assessment protocol employs a machined base plate to measure positional and rotational tracking data, offering simplicity, reproducibility, a high precision ground truth and accuracy. This protocol is now widely considered to be the standard method, but there is the limitation that measurement accuracy is a function of translation or rotation [17]. Optical tracking [16] and robots have also been used, however, these solutions are expensive and typically involve complicated calibration procedures [10].…”

Section: Introductionmentioning

confidence: 99%

“…Despite the growing popularity of EM tracking in interventional applications, significant tracking errors due to metallic objects (i.e., steel, aluminium and bronze) placed between the emitter and the sensor, and the use of some electronic devices, such as a C-arm unit, have been reported to cause disturbances to the magnetic field below 4.2 mm [8,13,[17][18][19][20]. Such errors can be particularly prevalent in clinical environments and their sources difficult to control.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Electromagnetic Tracking Accuracy for Endoscopic Ultrasound

Bonmati

Gurusamy

et al. 2017

Computer-Assisted and Robotic Endoscopy

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Endoscopic ultrasound (EUS) is a minimally-invasive imaging technique that can be technically difficult to perform due to the small field of view and uncertainty in the endoscope position. Electromagnetic (EM) tracking is emerging as an important technology in guiding endoscopic interventions and for training in endotherapy by providing information on endoscope location by fusion with pre-operative images. However, the accuracy of EM tracking could be compromised by the endoscopic ultrasound transducer. In this work, we quantify the precision and accuracy of EM tracking sensors inserted into the working channel of a flexible endoscope, with the ultrasound transducer turned on and off. The EUS device was found to have little (no significant) effect on static tracking accuracy although jitter increased significantly. A significant change in the measured distance between sensors arranged in a fixed geometry was found during a dynamic acquisition. In conclusion, EM tracking accuracy was not found to be significantly affected by the flexible endoscope.

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“…Indeed, several studies have shown that measurement uncertainty may vary considerably depending on the clinical setup. 7,8 To reduce tracking errors due to environmental interference, some manufacturers deployed direct current (DC) tracking systems. These systems measure the pose of the sensor relative to the transmitter once the magnetic field is stabilized.…”

Section: Introductionmentioning

confidence: 99%

Nonholonomic catheter path reconstruction using electromagnetic tracking

et al. 2015

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Purpose: Catheter path reconstruction is a necessary step in many clinical procedures, such as cardiovascular interventions and high-dose-rate brachytherapy. To overcome limitations of standard imaging modalities, electromagnetic tracking has been employed to reconstruct catheter paths. However, tracking errors pose a challenge in accurate path reconstructions. We address this challenge by means of a filtering technique incorporating the electromagnetic measurements with the nonholonomic motion constraints of the sensor inside a catheter.Methods: The nonholonomic motion model of the sensor within the catheter and the electromagnetic measurement data were integrated using an extended Kalman filter. The performance of our proposed approach was experimentally evaluated using the Ascension's 3D Guidance trakStar electromagnetic tracker. Sensor measurements were recorded during insertions of an electromagnetic sensor (model 55) along ten predefined ground truth paths. Our method was implemented in MATLAB and applied to the measurement data. Our reconstruction results were compared to raw measurements as well as filtered measurements provided by the manufacturer.Results: The mean of the root-mean-square (RMS) errors along the ten paths was 3.7 mm for the raw measurements, and 3.3 mm with manufacturer's filters. Our approach effectively reduced the mean RMS error to 2.7 mm.Conclusion: Compared to other filtering methods, our approach successfully improved the path reconstruction accuracy by exploiting the sensor's nonholonomic motion constraints in its formulation. Our approach seems promising for a variety of clinical procedures involving reconstruction of a catheter path.

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Electromagnetic tracking in surgical and interventional environments: usability study

Abstract: EM tracking can provide effective assistance to surgeons or interventional radiologists during procedures performed in a clinical or CBCT environment. Applications in the CT scanner demand precalibration to provide acceptable performance.

Cited by 55 publications

References 35 publications

Simultaneous Electromagnetic Tracking and Calibration for Dynamic Field Distortion Compensation

Simultaneous Electromagnetic Tracking and Calibration for Dynamic Field Distortion Compensation

Assessment of Electromagnetic Tracking Accuracy for Endoscopic Ultrasound

Nonholonomic catheter path reconstruction using electromagnetic tracking

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