gms | German Medical Science

58. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e. V. (DGNC)

Deutsche Gesellschaft für Neurochirurgie (DGNC) e. V.

26. bis 29.04.2007, Leipzig

Freehand calibration of intraoperative 3D ultrasound navigation

Freihandkalibrierung des intraoperativen 3D-Ultraschalls in der Neuronavigation

Meeting Abstract

  • corresponding author R. Haase - ICCAS Leipzig
  • D. Lindner - Klinik für Neurochirurgie, Universität Leipzig
  • C. Trantakis - Klinik für Neurochirurgie, Universität Leipzig
  • S. Arnold - Localite, Bonn
  • S. Bohn - ICCAS Leipzig
  • W. Korb - ICCAS Leipzig
  • J. Meixensberger - Klinik für Neurochirurgie, Universität Leipzig

Deutsche Gesellschaft für Neurochirurgie. 58. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC). Leipzig, 26.-29.04.2007. Düsseldorf: German Medical Science GMS Publishing House; 2007. DocP 028

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/dgnc2007/07dgnc283.shtml

Veröffentlicht: 11. April 2007

© 2007 Haase et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielf&aauml;ltigt, verbreitet und &oauml;ffentlich zug&aauml;nglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Objective: Tracked 3D ultrasound is an efficient tool for validity control of pre-operative planning, recognition of brain shift during the intervention, adjusting the operational path due to situational changes in an iterative technique, and finally, controlling of tumor removal. So far these systems are dedicated for one special application and are mostly developed as stand-alone devices. The aim of our study was the development of a simple calibration method for application of arbitrary ultrasound probes. Expenditure of time for a new calibration should less than 2 minutes. And the tool should work automatically in high accuracy and stability.

Methods: For calculating the transformation from the 2D ultrasound image to the 3D ultrasound slice we developed a CUBE calibration phantom. The calibration CUBE is a passive tracked plexiglas box with twisted nylon wires. The CUBE was digitized using a Faro Arm. Therefore the positions of the nylon wires in relation to the passive tracker markers are known. The wires were arranged in a special m-structure. Thus, the correct position of the segmented points in the 2D ultrasound image to the corresponding 3D points in the phantom can be calculated. The overall calibration transformation can be calculated. The new developed CALIBRATION software automatically segments the ultrasound points within the 2D US image in real-time. The program grabs the ultrasound image from an S-VHS connection, measures the ultrasound tracker coordinates as well as the phantom tracker coordinates and orientation, using an S-PACS interface client, for the tracking camera. The final transformation is calculated using a least square fitting algorithm based on 500 points.

Results: For accuracy validation a box with different pattern of wires was unsed. Then a scan of these cross wires and the corresponding transformation was performed using the calibrated 3D US navigation system. The accuracy was tested in different depths from 8 -12 cm using an 7.5 MHz ultrasound probe. The mean deviation was under 0.8±0.3 mm in all depths with a higher accuracy in 11 and 12 cm. The calibration process works stable and we had no influence on accuracy by different users.

Conclusions: The study demonstrates that the proposed method for calibration of different ultrasound probes yield in sufficient accuracy. Further, the man-machine interface is simple enough for routinely work. New calibration results within 2 minutes. This allows easy re-calibration in the OR to address changes of parameters or US probes.