Feuerstein Marco, Reichl Tobias, Vogel Jakob, Traub Joerg, Navab Nassir
Department of Media Science, Graduate School of Information Science, Nagoya University, Nagoya 464-8603, Japan.
IEEE Trans Med Imaging. 2009 Jun;28(6):951-67. doi: 10.1109/TMI.2008.2008954. Epub 2009 Feb 10.
Electromagnetic tracking is currently one of the most promising means of localizing flexible endoscopic instruments such as flexible laparoscopic ultrasound transducers. However, electromagnetic tracking is also susceptible to interference from ferromagnetic material, which distorts the magnetic field and leads to tracking errors. This paper presents new methods for real-time online detection and reduction of dynamic electromagnetic tracking errors when localizing a flexible laparoscopic ultrasound transducer. We use a hybrid tracking setup to combine optical tracking of the transducer shaft and electromagnetic tracking of the flexible transducer tip. A novel approach of modeling the poses of the transducer tip in relation to the transducer shaft allows us to reliably detect and significantly reduce electromagnetic tracking errors. For detecting errors of more than 5 mm, we achieved a sensitivity and specificity of 91% and 93%, respectively. Initial 3-D rms error of 6.91 mm were reduced to 3.15 mm.
电磁跟踪目前是定位诸如柔性腹腔镜超声换能器等柔性内窥镜器械最有前景的手段之一。然而，电磁跟踪也容易受到铁磁材料的干扰，这会使磁场失真并导致跟踪误差。本文提出了在定位柔性腹腔镜超声换能器时实时在线检测和减少动态电磁跟踪误差的新方法。我们使用混合跟踪设置，将换能器轴的光学跟踪与柔性换能器尖端的电磁跟踪相结合。一种对换能器尖端相对于换能器轴的姿态进行建模的新颖方法使我们能够可靠地检测并显著减少电磁跟踪误差。对于检测大于5毫米的误差，我们分别实现了91%的灵敏度和93%的特异性。初始6.91毫米的三维均方根误差降低到了3.15毫米。
