Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, CO 80045, USA.
Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Curr Oncol. 2023 May 16;30(5):5054-5061. doi: 10.3390/curroncol30050382.
Fiducial markers are utilized for image guided radiotherapy (IGRT) alignment during the delivery of liver stereotactic body radiosurgery (SBRT). There are limited data demonstrating the impact of matching fiducials on the accuracy of liver SBRT. This study quantifies the benefit of fiducial-based alignment and improvements in inter-observer reliability. Nineteen patients with 24 liver lesions were treated with SBRT. Target localization was performed using fiducial markers on cone-beam computed tomography (CBCT). Each CBCT procedure was retrospectively realigned to match both the liver edge and fiducial markers. The shifts were recorded by seven independent observers. Inter-observer variability was analyzed by calculating the mean error and uncertainty for the set-up. The mean absolute Cartesian error observed from fiducial and liver edge-based alignment was 1.5 mm and 5.3 mm, respectively. The mean uncertainty from fiducial and liver edge-based alignment was 1.8 mm and 4.5 mm, respectively. An error of 5 mm or greater was observed 50% of the time when aligning to the liver surface versus 5% of the time when aligning to fiducial markers. Aligning to the liver edge significantly increased the error, resulting in increased shifts when compared to alignment to fiducials. Tumors of 3 cm or farther from the liver dome had higher mean errors when aligned without fiducials (4.8 cm vs. 4.4 cm, = 0.003). Our data support the use of fiducial markers for safer and more accurate liver SBRT.
基准标记用于在肝立体定向体部放射治疗 (SBRT) 中进行图像引导放射治疗 (IGRT) 对准。只有有限的数据表明匹配基准标记对肝 SBRT 准确性的影响。本研究量化了基于基准标记的对准的益处和观察者间可靠性的提高。19 例 24 个肝病变患者接受 SBRT 治疗。使用锥形束 CT (CBCT) 上的基准标记进行靶区定位。每个 CBCT 程序均进行回顾性重新对准，以匹配肝边缘和基准标记。记录了七个独立观察者的偏移量。通过计算设置的平均误差和不确定性来分析观察者间的可变性。基于基准标记和肝边缘的对准观察到的平均绝对笛卡尔误差分别为 1.5 毫米和 5.3 毫米。基于基准标记和肝边缘的对准的平均不确定性分别为 1.8 毫米和 4.5 毫米。当与肝表面对准时，观察到 50%的时间误差为 5 毫米或更大，而当与基准标记对准时，只有 5%的时间误差为 5 毫米或更大。与基准标记对准相比，与肝边缘对准会显著增加误差，从而导致更大的偏移。与无基准标记对准相比，距离肝顶 3 厘米或更远的肿瘤具有更高的平均误差（4.8 厘米对 4.4 厘米， = 0.003）。我们的数据支持使用基准标记进行更安全、更准确的肝 SBRT。
