Comparing position and orientation accuracy of different electromagnetic sensors for tracking during interventions.

Abstract

To compare the position and orientation accuracy between using one 6-degree of freedom (DOF) electromagnetic (EM) sensor, or the position information of three 5DOF sensors within the scope of tumor tracking. The position accuracy of Northern Digital Inc Aurora 5DOF and 6DOF sensors was determined for a table-top field generator (TTFG) up to a distance of 52cm. For each sensor 716 positions were measured for 10s at 15Hz. Orientation accuracy was determined for each of the orthogonal axis at the TTFG distances of 17, 27, 37 and 47cm. For the 6DOF sensors, orientation was determined for sensors in-line with the orientation axis, and perpendicular. 5DOF orientation accuracy was determined for a theoretical 4cm tumor. An optical tracking system was used as reference. Position RMSE and jitter were comparable between the sensors and increasing with distance. Jitter was within 0.1cm SD within 45cm distance to the TTFG. Position RMSE was approximately 0.1cm up to 32cm distance, increasing to 0.4cm at 52cm distance. Orientation accuracy of the 6DOF sensor was within 1[Formula: see text], except when the sensor was in-line with the rotation axis perpendicular to the TTFG plane (4[Formula: see text] errors at 47cm). Orientation accuracy using 5DOF positions was within 1[Formula: see text] up to 37cm and 2[Formula: see text] at 47cm. The position and orientation accuracy of a 6DOF sensor was comparable with a sensor configuration consisting of three 5DOF sensors. To achieve tracking accuracy within 1mm and 1[Formula: see text], the distance to the TTFG should be limited to approximately 30cm.