Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
Department of Radiation Oncology, Northwell Health Cancer Institute, New Hyde Park, NY 11042, USA.
Phys Med. 2024 Sep;125:104495. doi: 10.1016/j.ejmp.2024.104495. Epub 2024 Aug 3.
Surface-guided imaging (SGI) is increasingly utilized to monitor patient motion during deep inspiration breath hold (DIBH) in radiotherapy. Understanding the association between surface and internal motion is crucial for effective monitoring.
To investigate the relation between motion detected by SGI using surface-guided radiotherapy (SGRT) and internal motion measured through diaphragm tracking on kV projections acquired with DIBH for online CBCT.
Both SGI and kV were simultaneously acquired for ten patients over a total of 200 breath holds (BH). Diaphragm tracking was performed using second-degree polynomial curve fitting on the derivative images for each kV projection and high-pass filtering at 1/30 Hz to remove rotational effects. The superior-inferior (SI) and anterior-posterior (AP) motions of SGI were then compared to kV tracking using various statistical measures.
The correlation (individuals' median: -0.07 to 0.73) was a suboptimal metric for the BH data. The median and 95th percentile absolute differences between SGI-SI and kV were 0.73 mm and 3.46 mm, respectively, during DIBH. For SGI-AP, the corresponding values were 0.55 mm and 2.80 mm. For inter-BH measurements, the contingency table based on a 3 mm threshold indicated surface/diaphragm motion agreement for SGI-SI/kV and SGI-AP/kV was 61 % and 56 %, respectively.
Both intra- and inter-BH measurements indicated a limited association between surface and diaphragm motion, with certain constraints noted due to kV tracking and DIBH data. These findings warrant further investigation into the association between surface and internal motion.
表面引导成像（SGI）越来越多地用于在放射治疗中的深吸气屏气（DIBH）期间监测患者的运动。了解表面运动与内部运动之间的关联对于有效的监测至关重要。
研究使用表面引导放疗（SGRT）的 SGI 检测到的运动与通过 DIBH 获取的千伏投影上的膈肌跟踪测量到的内部运动之间的关系，以进行在线 CBCT。
对十名患者总共 200 次屏气（BH）进行了同时采集 SGI 和千伏。使用二次多项式曲线拟合对每个千伏投影的导数图像进行膈肌跟踪，并使用 1/30 Hz 的高通滤波器去除旋转效应。然后使用各种统计措施将 SGI 的上下（SI）和前后（AP）运动与千伏跟踪进行比较。
BH 数据的相关系数（个体中位数：-0.07 至 0.73）是一个次优的指标。在 DIBH 期间，SGI-SI 和 kV 之间的中位数和 95%百分位绝对差值分别为 0.73 毫米和 3.46 毫米。对于 SGI-AP，相应的值分别为 0.55 毫米和 2.80 毫米。对于 BH 之间的测量，基于 3 毫米阈值的列联表表明，SGI-SI/kV 和 SGI-AP/kV 的表面/膈肌运动一致性分别为 61%和 56%。
BH 内和 BH 之间的测量均表明表面和膈肌运动之间的关联有限，由于 kV 跟踪和 DIBH 数据存在某些限制。这些发现需要进一步研究表面运动与内部运动之间的关系。
