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. Author manuscript; available in PMC: 2012 Mar 12.
Published in final edited form as: Med Image Comput Comput Assist Interv. 2007;10(Pt 2):59–67. doi: 10.1007/978-3-540-75759-7_8

Fig. 2.

Fig. 2

Left: Photograph of manipulator during initial registration. An attachment is placed concentrically over the needle channel. The tube contains two tubular markers. Two additional markers are placed into the main axis of the manipulator. Right: Example of two binary reformatted MR images axial to a fiducial marker. The segmentation algorithm finds the best fitting circle center indicated by a big cross on both images. The algorithm is able to find the center, even when air bubbles in the marker on the left contaminate the image. Small crosses indicate the border of the marker.