Magnetic tracking in the operation room using the da Vinci(®) telemanipulator is feasible

Abstract

In recent years, robotic assistance for surgical procedures has grown on a worldwide scale, particularly for use in more complex operations. Such operations usually require meticulous handling of tissue, involve a narrow working space and limit the surgeon's sense of orientation in the human body. Improvement in both tissue handling and working within a narrow working space might be achieved through the use of robotic assistance. Soft tissue navigation might improve orientation by visualizing important target and risk structures intraoperatively, thereby possibly improving patient outcome. Prerequisites for navigation are its integration into the surgical workflow and accurate localization of both the instruments and patient. Magnetic tracking allows for good integration but is susceptible to distortion through metal or electro-magnetic interference, which may be caused by the operation table or a robotic system. We have investigated whether magnetic tracking can be used in combination with the da Vinci(®) (DV) telemanipulator in terms of stability and precision. We used a common magnetic tracking system (Aurora(®), NDI Inc.) with the DV in a typical operation setup. Magnetic field distortion was evaluated using a measuring facility, with the following reference system: without any metal (R), operation table alone (T), DV in standby (D) and DV in motion (Dm). The maximum error of the entire tracking volume for R, T, D and Dm was 9.9, 32.8, 37.9 and 37.2 mm, respectively. Limiting the tracking volume to 190 mm (from cranial to caudal) resulted in a maximum error of 4.0, 8.3, 8.5 and 8.9 mm, respectively. When used in the operation room, magnetic tracking shows high errors, mainly due to the operation table. The target area should be limited to increase accuracy, which is possible for most surgical applications. The use of the da Vinci(®) telemanipulator only slightly aggravates the distortion and can thus be used in combination with magnetic tracking systems.

Keywords: Electromagnetic tracking; Minimally invasive surgery; Navigation; Robotic surgery.

Fig. 1

Wooden metal-free measuring facility with 12 polyvinyl chloride (PVC) tubes, thus enabling laparoscopic instruments to be used between the tubes

Fig. 2

Realistic setup in the operating room with anesthesia console, laparoscopic turret and the da Vinci surgical system, as used in laparoscopic nissen fundoplication

Fig. 3

Operating table Alphamaquet 1150, with outlined ferromagnetic material (yellow). EMT Electromagnetic tracking system

Fig. 4

Left Static da Vinci—magnetic sensors were pulled through a PVC tube. Right da Vinci^® was constantly in motion using the da Vinci console

Fig. 5

Reference evaluation shows the virtual three-dimensional (3D) scene by MITK: interactively defined reference centerlines are red, and measured positions with the EMT system at corresponding centerline positions are yellow. The yellow and green lines should always stay close to the red line for high accuracy

Fig. 6

Results of the exemplary reference measurements for each separate tube showing the respective maximum distance from the centerline. The y-axis represents the extent of shift (of the tracked position); the x-axis represents the x-coordinate of the tracking volume

Fig. 7

Measurement without the da Vinci system for all tubes, with the measuring facility lifted 50 mm on the operation table

Fig. 8

Overview of the maximal error for all tubes (according to the setup in the x-axis), measured orthogonally to the reference lines