Hayashi Naoki, Obata Yasunori, Uchiyama Yukio, Mori Yoshimasa, Hashizume Chisa, Kobayashi Tatsuya
Nagoya Radiosurgery Center, Nagoya Kyoritsu Hospital, Nagoya, Japan.
Int J Radiat Oncol Biol Phys. 2009 Oct 1;75(2):549-57. doi: 10.1016/j.ijrobp.2009.02.080.
The purpose of this study was to evaluate the accuracy of a new version of the ExacTrac X-ray (ETX) system with statistical analysis retrospectively in order to determine the tolerance of systematic components of spatial uncertainties with the Novalis system.
Three factors of geometrical accuracy related to the ETX system were evaluated by phantom studies. First, location dependency of the detection ability of the infrared system was evaluated. Second, accuracy of the automated calculation by the image fusion algorithm in the patient registration software was evaluated. Third, deviation of the coordinate scale between the ETX isocenter and the mechanical isocenter was evaluated. From the values of these examinations and clinical experiences, the total spatial uncertainty with the Novalis system was evaluated.
As to the location dependency of the detection ability of the infrared system, the detection errors between the actual position and the detected position were 1% in translation shift and 0.1 degrees in rotational angle, respectively. As to the accuracy of patient verification software, the repeatability and the coincidence of the calculation value by image fusion were good when the contrast of the X-ray image was high. The deviation of coordinates between the ETX isocenter and the mechanical isocenter was 0.313 +/- 0.024 mm, in a suitable procedure.
The spatial uncertainty will be less than 2 mm when suitable treatment planning, optimal patient setup, and daily quality assurance for the Novalis system are achieved in the routine workload.
本研究的目的是通过回顾性统计分析评估新版ExacTrac X射线（ETX）系统的准确性，以确定Novalis系统空间不确定性系统组件的容差。
通过体模研究评估了与ETX系统相关的几何精度的三个因素。首先，评估了红外系统检测能力的位置依赖性。其次，评估了患者配准软件中图像融合算法自动计算的准确性。第三，评估了ETX等中心与机械等中心之间坐标比例的偏差。根据这些检查的值和临床经验，评估了Novalis系统的总空间不确定性。
关于红外系统检测能力的位置依赖性，实际位置与检测位置之间的检测误差在平移偏移中为1%，在旋转角度中为0.1度。关于患者验证软件的准确性，当X射线图像的对比度较高时，图像融合计算值的重复性和一致性良好。在适当的程序中，ETX等中心与机械等中心之间的坐标偏差为0.313 +/- 0.024 mm。
在常规工作量中，当实现Novalis系统的适当治疗计划、最佳患者设置和每日质量保证时，空间不确定性将小于2 mm。
