Tanimoto Yuki, Sugimoto Kohei, Koshi Kazunobu, Hiroshige Akira, Yoshida Shohei, Fujita Yoshiki, Nakahira Atsuki, Nakanishi Daiki, Honda Hirofumi, Oita Masataka
Department of Radiology, NHO Kure Medical Center and Chugoku Cancer Center, Kure, Hiroshima, Japan.
Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, Kurashiki, Okayama, Japan.
J Appl Clin Med Phys. 2025 Jun;26(6):e70119. doi: 10.1002/acm2.70119. Epub 2025 May 19.
Accurate beam data acquisition using three-dimensional (3D) water tanks is essential for beam commissioning and quality control (QC) in clinical radiation therapy. This study introduces a novel method for quantitative QC of the system, utilizing MV images and webcam videos. The stability of the motor drive speed and the positional accuracy of the fixture were evaluated under two measurement modes: "continuous mode" and "step-by-step mode."
A TRUFIX mounting system (PTW Freiburg Inc., Germany) was used to attach the center of the steel ball to its top, ensuring alignment with the water surface of the tank. To assess deviations from the radiation isocenter, MV images were acquired and compared with digitally reconstructed radiographs (DRRs). These evaluations were performed at different speed settings (slow, medium, and fast) using ET CT Body Marker (BRAINLAB Inc., USA) mounted on the drive unit. A webcam was utilized to capture the images, and custom-developed tracking software was employed to analyze deviations in driving speed and positional errors.
The mean error of the radiation isocenter was 0.37 ± 0.09 mm. As the motor drive speed increased, the discrepancy between the set speed and the actual speed observed in the analysis also became larger. In "continuous mode," the deviation from the displayed value was greater than that observed in "step-by-step mode."
It is demonstrated that the proposed analysis method can quantitatively evaluate radiation isocenter misalignment, tank setup position deviation, and both the indicated drive speed values and their stability. At higher drive speeds, the "step-by-step mode" showed smaller deviations from the indicated values.
在临床放射治疗中，使用三维（3D）水箱进行精确的射束数据采集对于射束调试和质量控制（QC）至关重要。本研究引入了一种利用兆伏（MV）图像和网络摄像头视频对系统进行定量质量控制的新方法。在“连续模式”和“逐步模式”两种测量模式下，评估了电机驱动速度的稳定性和夹具的位置精度。
使用TRUFIX安装系统（德国PTW弗莱堡公司）将钢球中心连接到其顶部，确保与水箱水面对齐。为了评估与放射等中心的偏差，采集了MV图像并与数字重建射线照片（DRR）进行比较。使用安装在驱动单元上的ET CT身体标记物（美国BRAINLAB公司）在不同速度设置（慢、中、快）下进行这些评估。利用网络摄像头捕获图像，并使用定制开发的跟踪软件分析驱动速度偏差和位置误差。
放射等中心的平均误差为0.37±0.09毫米。随着电机驱动速度的增加，分析中观察到的设定速度与实际速度之间的差异也变得更大。在“连续模式”下，与显示值的偏差大于“逐步模式”下观察到的偏差。
结果表明，所提出的分析方法可以定量评估放射等中心的对准误差、水箱设置位置偏差以及指示的驱动速度值及其稳定性。在较高驱动速度下，“逐步模式”与指示值的偏差较小。
