Assessment of position repeatability of surgical EM tracking systems employing magnetic field model

Position repeatability is a very important issue in navigation systems, especially in medical applications, where the precision of about 1-2 mm is required in many procedures. This paper proposes an effective procedure for assessing the position repeatability error of electromagnetic tracking systems (EMTSs) for surgical navigation, by using a model of the magnetic field based on magnetic dipole approximation of the transmitting coils. The proposed method allows to obtain quite accurate estimation of position repeatability errors even if the system parameters are affected by uncertainty. The new approach is applied on a novel EMTS prototype, developed to improve the state-of-the-art of current commercial systems. The obtained results are compared with the ones obtained in previous experimental tests without using magnetic field model and with the need to have more measurement data. Finally, the accuracy of the proposed method is evaluated for different orientations of the sensor.