EXACTRAC x-ray and beam isocenters-What's the difference?
EXACTRAC x-ray and beam isocenters-What's the difference?
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DOI：
10.1118/1.3685581
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发表时间：
2012-03-01
期刊：
影响因子：
3.8
通讯作者：
Carl, Jesper
中科院分区：
文献类型：
--
作者：
Tideman Arp, Dennis;Carl, Jesper
目的：旨在评价在BRAINLAB的EXACTRAC系统中实现的图像引导系统的等中心点相对于直线加速器辐射等中心点的几何精度。随后纠正的X射线等中心的EXACTRAC系统的任何几何差异之间的两个isocents.Methods：五个瓦里安直线加速器都配备了电子成像设备和EXACTRAC与机器人从BRAINLAB进行了评估。该装置使用市售Winston-Lutz体模和自制可调底座。使用直线加速器的电子射野成像设备在不同机架角度采集MV图像。使用EXACTRAC系统采集X射线图像的立体对。使用EXACTRAC系统的商业软件评价外部激光等中心点和EXACTRAC等中心点位置之间的偏差。使用内部生产的软件分析MV图像并评价外部激光等中心点与直线加速器辐射等中心点之间的偏差。随后，计算辐射等中心与EXACTRAC系统的等中心之间的偏差。一种新的方法来校准的EXACTRAC系统的等中心，以减少辐射等中心和EXACTRAC等中心之间的偏差。结果：为了评估几何精度的三维偏差矢量计算每个相对等中心位置。外部激光等中心点和EXACTRAC系统的等中心点之间的3D偏差在0.21至0.42 mm之间变化。外部激光等中心点和直线加速器辐射等中心点之间的3D偏差在0.37至0.83 mm之间变化。辐射等中心点和EXACTRAC系统的等中心点之间的3D偏差在0.31至1.07 mm之间变化。EXACTRAC等中心校准方法的一个直线加速器的三维偏差从0.90到0.23毫米减少。结果是复杂的，由于日常维护的直线加速器，包括激光校准。有必要重复测量，以执行EXACTRAC等中心点的校准。结论：直线加速器辐射等中心点和EXACTRAC等中心点之间的偏差的顺序，可能有临床意义。应用了一种校准EXACTRAC系统等中心点的替代方法，并减少了两个等中心点之间的偏差。VC 2012年美国医学物理学家协会。[DOI：10.1118/1.3685581]
Purpose: To evaluate the geometric accuracy of the isocenter of an image- guidance system, as implemented in the EXACTRAC system from BRAINLAB, relative to the linear accelerator radiation isocenter. Subsequently to correct the x-ray isocenter of the EXACTRAC system for any geometric discrepancies between the two isocenters.Methods: Five Varian linear accelerators all equipped with electronic imaging devices and EXACTRAC with robotics from BRAINLAB were evaluated. A commercially available Winston-Lutz phantom and an in-house made adjustable base were used in the setup. The electronic portal imaging device of the linear accelerators was used to acquire MV-images at various gantry angles. Stereoscopic pairs of x-ray images were acquired using the EXACTRAC system. The deviation between the position of the external laser isocenter and the EXACTRAC isocenter was evaluated using the commercial software of the EXACTRAC system. In-house produced software was used to analyze the MV-images and evaluate the deviation between the external laser isocenter and the radiation isocenter of the linear accelerator. Subsequently, the deviation between the radiation isocenter and the isocenter of the EXACTRAC system was calculated. A new method of calibrating the isocenter of the EXACTRAC system was applied to reduce the deviations between the radiation isocenter and the EXACTRAC isocenter.Results: To evaluate the geometric accuracy a 3D deviation vector was calculated for each relative isocenter position. The 3D deviation between the external laser isocenter and the isocenter of the EXACTRAC system varied from 0.21 to 0.42 mm. The 3D deviation between the external laser isocenter and the linac radiation isocenter ranged from 0.37 to 0.83 mm. The 3D deviation between the radiation isocenter and the isocenter of the EXACTRAC system ranged from 0.31 to 1.07 mm. Using the new method of calibrating the EXACTRAC isocenter the 3D deviation of one linac was reduced from 0.90 to 0.23 mm. The results were complicated due to routine maintenance of the linac, including laser calibration. It was necessary to repeat the measurements in order to perform the calibration of the EXACTRAC isocenter.Conclusions: The deviations between the linac radiation isocenter and the EXACTRAC isocenter were of an order that may have clinical relevance. An alternative method of calibrating the isocenter of the EXACTRAC system was applied and reduced the deviations between the two isocenters. VC 2012 American Association of Physicists in Medicine. [DOI: 10.1118/1.3685581]