Intrafraction imaging‐based motion management systems for external beam radiotherapy can rely on internal surrogate structures when the target is not easily visualized. This work evaluated the validity of using liver vessels as internal surrogates for the estimation of liver tumor motion. Vessel and tumor motion were assessed using ten two‐dimensional sagittal MR cine datasets collected on the ViewRay MRIdian. For each case, a liver tumor and at least one vessel were tracked for 175 s. A tracking approach utilizing block matching and multiple simultaneous templates was applied. Accuracy of the tracked motion was calculated from the error between the tracked centroid position and manually defined ground truth annotations. The patient’s abdomen surface and diaphragm were manually annotated in all frames. The Pearson correlation coefficient (CC) was used to compare the motion of the features and tumor in the anterior–posterior (AP) and superior–inferior (SI) directions. The distance between the centroids of the features and the tumors was calculated to assess if feature proximity affects relative correlation, and the tumor range of motion was determined. Intra‐ and interfraction motion amplitude variabilities were evaluated to further assess the relationship between tumor and feature motion. The mean CC between the motion of the vessel and the tumor were 0.85 ± 0.11 (AP) and 0.92 ± 0.04 (SI), 0.83 ± 0.11 (AP) and −0.89 ± 0.06 (SI) for the surface and tumor, and 0.80 ± 0.17 (AP) and 0.94 ± 0.03 (SI) for the diaphragm and tumor. For intrafraction analysis, the average amplitude variability was 2.47 ± 0.77 mm (AP) and 3.14 ± 1.49 mm (SI) for the vessels, 2.70 ± 1.08 mm (AP) and 3.43 ± 1.73 mm (SI) for the surface, and 2.76 ± 1.41 mm (AP) and 2.91 ± 1.38 mm (SI) for the diaphragm. No relationship between distance and motion correlation was observed. The motion of liver tumors and liver vessels was well correlated, making vessels a suitable surrogate for tumor motion in the liver.

中文翻译：

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肝脏中肿瘤与血管运动相关性的研究。

当目标不容易观察到时，用于外部束放射治疗的基于内部成像的运动管理系统可以依靠内部替代结构。这项工作评估了使用肝脏血管作为内部替代物评估肝肿瘤运动的有效性。使用在ViewRay MRIdian上收集的十个二维矢状MR电影数据集评估血管和肿瘤运动。对于每种情况，追踪肝肿瘤和至少一个血管持续175 s。采用了利用块匹配和多个同时模板的跟踪方法。根据跟踪的质心位置和手动定义的地面真实情况注释之间的误差，计算跟踪的运动的准确性。在所有框架中手动注释患者的腹部表面和surface肌。皮尔逊相关系数（CC）用于比较特征和肿瘤在前后（AP）和上下（SI）方向上的运动。计算特征质心与肿瘤之间的距离，以评估特征邻近度是否影响相对相关性，并确定肿瘤的运动范围。评估了术中和术中运动幅度变异性，以进一步评估肿瘤与特征运动之间的关系。血管运动与肿瘤之间的平均CC为0.85±0.11（AP）和0.92±0.04（SI），表面和肿瘤的0.83±0.11（AP）和-0.89±0.06（SI）和0.80± the肌和肿瘤为0.17（AP）和0.94±0.03（SI）。对于分数内分析，平均幅度变化为2.47±0.77 mm（AP）和3.14±1。容器为49毫米（SI），表面为2.70±1.08毫米（AP）和3.43±1.73毫米（SI），隔膜为2.76±1.41毫米（AP）和2.91±1.38毫米（SI）。没有观察到距离和运动相关性之间的关系。肝肿瘤的运动与肝血管的相关性很好，使血管成为肝肿瘤运动的合适替代物。