High-precision evaluation of electromagnetic tracking

PurposeNavigation in high-precision minimally invasive surgery (HP-MIS) demands high tracking accuracy in the absence of line of sight (LOS). Currently, no tracking technology can satisfy this requirement. Electromagnetic tracking (EMT) is the best tracking paradigm in the absence of LOS despite limited accuracy and robustness. Novel evaluation protocols are needed to ensure high-precision and robust EMT for navigation in HP-MIS.MethodsWe introduce a novel protocol for EMT measurement evaluation featuring a high-accuracy phantom based on LEGO (R), which is calibrated by a coordinate measuring machine to ensure accuracy. Our protocol includes relative sequential positions and an uncertainty estimation of positioning. We show effects on distortion compensation using a learned interpolation model.ResultsOur high-precision protocol clarifies properties of errors and uncertainties of EMT for high-precision use cases. For EMT errors reaching clinically relevant 0.2mm, our design is 5-10 times more accurate than previous protocols with 95% confidence margins of 0.02mm. This high-precision protocol ensures the performance improvement in compensated EMT by 0.05mm.ConclusionOur protocol improves the reliability of EMT evaluations because of significantly lower protocol-inherent uncertainties. To reduce patient risk in HP-MIS and to evaluate magnetic field distortion compensation, more high-accuracy protocols such as the one proposed here are required.