A Direction Space Interpolation Technique for Calibration of Electromagnetic Surgical Navigation Systems

Abstract

A new generation of electromagnetic (EM) navigation systems with extremely compact sensors have great potential for clinical applications requiring that surgical devices be tracked within a patient’s body. However, electro-magnetic field distortions limit the accuracy of such devices. Further, the errors may be sensitive both to position and orientation of EM sensors within the field. This paper presents a computationally efficient method for in-situ 5 DOF calibration of the basic sensors of a typical EM system (Northern Digital’s Aurora), and presents preliminary results demonstrating an improvement of approximately 2.6 : 1 positional accuracy and 1.6 : 1 for orientation even when the sensors are moved through arbitrary orientation changes. This work represents one step in a larger effort to understand the field distortions associated with these systems and to develop effective and predictable calibration and registration strategies for their use in stereotactic image-guided interventions.

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