Evaluation of Position RMS Error from Magnetic Field Gradient for Surgical EM Tracking Systems

Electromagnetic tracking systems (EMTSs) are widely used in surgical operations, supporting the surgeon for the localization of tools during intervention. In this paper we describe a novel EMTS prototype for surgical navigation, based on a magnetic field generator (FG) composed of five transmitting coils, to advance the state-of-the-art of current commercial systems.The root mean square error (or mean radial spherical error) of position estimation for the tracking system is characterized through propagation of the voltage measurement error of the magnetic sensor, for different orientations and positions, and taking into account magnetic field gradient. This method does not require a magnetic field model, resulting useful for fast and not expensive assessment of different EMTSs with different transmitting coils’ arrangement. In this paper a measurement volume of 400 mm x 500 mm x 400 mm has been considered.The results show good performance with a standard deviation of position lower than 1 mm in almost the entire measurement volume.