Evaluation of a miniature electromagnetic position tracker
Evaluation of a miniature electromagnetic position tracker
复制标题
DOI：
10.1118/1.1508377
复制
发表时间：
2002-10-01
期刊：
影响因子：
3.8
通讯作者：
Birkfellner, W
中科院分区：
文献类型：
--
作者：
Hummel, J;Figl, M;Birkfellner, W
小型化电磁数字化仪的出现为使用柔性仪器的计算机辅助干预开辟了各种潜在的临床应用;内窥镜或导管可以很容易地在体内跟踪。关于新的应用，系统的失真引起的各种材料，如封闭的金属环，导丝，导管，和超声扫描头在本文中系统地评估了一个新的商业跟踪系统。我们使用电磁跟踪系统Aurora（TM）（Mednetix/CH，NDI/Can）;使用运行SuSE Linux 7.1（SuSE，Nurnberg）的PC的串行端口获取数据。引入数字化仪体积的物体包括不同直径的线环、导丝、光学跟踪工具、超声（US）扫描头、带有径向超声扫描头的内窥镜以及手术室和介入室中使用的各种其他物体。除此之外，我们还确定了C形臂透视装置的影响。为了量化系统的可靠性，将小型化传感器安装在非金属测量架上，同时将发射器固定在数字化仪范围内的三个不同距离处。跟踪器被证明对靠近发射器的材料引起的失真更敏感（距离发射器100 mm和200 mm之间的金属丝环的平均失真误差为13.6 mm +/- 16.6 mm）。传感器附近的材料（距离小于100 mm）引起的变形很小（典型误差为2.2 mm +/- 1.9 mm）。C形臂透视装置造成相当大的失真，并限制了跟踪器的可靠性（失真误差18.6 mm +/- 24.9 mm）。由US扫描头产生的失真在距发射器小于约100圈的距离处很高。当扫描头水平放置并靠近传感器时，失真也会增加（当扫描头放置在距离传感器100 mm的距离内时，平均误差为4.1 mm +/-1.5 mm）。当超音波机器被开启时，失真会稍高。我们也评估了常用医疗仪器对距离测量的影响。对于这些测量，与已知距离200 mm的平均偏差为3.0 mm +/- 1.5 mm（未失真距离测量值为1.5 mm +/- 0.3 mm）。偏差还取决于发射器和传感器之间的相对取向。结果表明，微型跟踪系统开辟了新的前景，在手术中的应用，一个灵活的仪器是在体内进行跟踪。由金属物体引起的显著失真仅在最坏的情况下发生，例如，在靠近发射器的封闭的、unisolated线环或C形臂荧光单元存在的情况下，并且可以通过适当的使用来避免。(C)2002年美国医学物理学家协会。
The advent of miniaturized electromagnetic digitizers opens a variety of potential clinical applications for computer aided interventions using flexible instruments; endoscopes or catheters can easily be tracked within the body. With respect to the new applications, the systematic distortions induced by various materials such as closed metallic loops, wire guides, catheters, and ultrasound scan heads were systematically evaluated in this paper for a new commercial tracking system. We employed the electromagnetic tracking system Aurora(TM) (Mednetix/CH, NDI/Can); data were acquired using the serial port of a PC running SuSE Linux 7.1 (SuSE, Gmbh, Nurnberg). Objects introduced into the digitizer volume included wire loops of different diameters, wire guides, optical tracking tools, an ultrasonic (US) scan head, an endoscope with radial ultrasound scan head and various other objects used in operating rooms and interventional suites. Beyond this, we determined the influence of a C-arm fluoroscopy unit. To quantify the reliability of the system, the miniaturized sensor was mounted on a nonmetallic measurement rack while the transmitter was fixed at three different distances within the digitizer range. The tracker was shown to be more sensitive to distortions caused by materials close to the emitter (average distortion error 13.6 mm +/- 16.6 mm for wire loops positioned at a distance between 100 mm. and 200 mm from the emitter). Distortions caused by materials near the sensor (distances smaller than 100 mm) are small (typical error 2.2 mm +/- 1.9 mm). The C-arm fluoroscopy unit caused considerable distortions and limits the reliability of the tracker (distortion error 18.6 mm +/- 24.9 mm). Distortions resulting from the US scan head are high at distances smaller than about 100 turn from the emitter. The distortions also increase when the scan head is positioned horizontally and close to the sensor (average error 4.1 mm +/- 1.5 mm when the scan head is positioned within a distance of 100 mm from the sensor). The distortions are slightly higher when the ultrasound machine is switched on. We also evaluated the influence of common medical instruments on distance measurements. For these measurements the average deviation from the known distance of 200 mm amounted to 3.0 mm +/- 1.5 mm(undistorted distance measurement 1.5 mm +/- 0.3 mm). The deviations also depend on the relative orientation between emitter and sensor. The results demonstrate that the miniature tracking system opens up new perspectives with regard to surgery applications where a flexible instrument is to be tracked within the body. Significant distortions caused by metallic objects only occur in the worst cases, for example, in the presence of a closed, unisiolated wire loop or a C-arm fluorescence unit close to the emitter and which can be avoided by suitable usage. (C) 2002 American Association of Physicists in Medicine.