Reproducibility of the external surface position in left-breast DIBH radiotherapy with spirometer-based monitoring
Reproducibility of the external surface position in left-breast DIBH radiotherapy with spirometer-based monitoring
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DOI：
10.1120/jacmp.v15i1.4494
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发表时间：
2014-01-01
影响因子：
2.1
通讯作者：
Baroni, Guido
中科院分区：
文献类型：
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作者：
Fassi, Aurora;Ivaldi, Giovanni B.;Baroni, Guido
左侧乳腺癌放射治疗中的深吸气屏气 (DIBH) 可以减少心脏和肺部剂量，而不会影响目标覆盖范围。选择最合适的 DIBH 监测技术是一个至关重要的问题。我们通过评估单个 DIBH（DIBH 内）内以及同一治疗疗程（分次内）或不同疗程（间次）中执行的 DIBH 之间的外表面位置的变异性，评估了由肺活量测定装置控制的 DIBH 的稳定性和再现性。该研究包括 7 名接受基于肺活量计的 DIBH 放射治疗的左乳腺癌患者。在 6 到 8 个治疗疗程中进行 29-43 个 DIBH 期间，使用红外光学跟踪记录放置在患者胸腹部表面的 7 到 11 个被动标记的 3D 坐标。获得的结果显示，即使在恒定的吸气量下，不同会话之间的外表面沿单个方向的位移也高达 6.3 毫米。乳腺被动标记位置间变异的中位值在横向方向上为 2.9 毫米（范围 1.9-4.8 毫米），在前后方向上为 3.6 毫米（范围 2.2-4.6 毫米），在头尾方向上为 4.3 毫米（范围 2.8-6.2 毫米）。就治疗计划而言，目标和处于危险中的器官没有显着的剂量分布变化，证实了所应用的临床边缘（15毫米）足以补偿测量的设置不确定性。这项研究表明，基于肺活量计的控制并不能保证左乳 DIBH 放射治疗中外表面的稳定且可重复的位置，这表明当需要减少边缘和设置不确定性以改善正常组织保护并降低心肺毒性时，需要更强大的 DIBH 监测技术。
Deep inspiration breath hold (DIBH) in left-sided breast cancer radiotherapy treatments allows for a reduction in cardiac and pulmonary doses without compromising target coverage. The selection of the most appropriate technology for DIBH monitoring is a crucial issue. We evaluated the stability and reproducibility of DIBHs controlled by a spirometric device, by assessing the variability of the external surface position within a single DIBH (intra-DIBH) and between DIBHs performed in the same treatment session (intrafraction) or in different sessions (interfraction). The study included seven left-breast cancer patients treated with spirometer-based DIBH radiotherapy. Infrared optical tracking was used to record the 3D coordinates of seven to eleven passive markers placed on the patient's thoraco-abdominal surface during 29-43 DIBHs performed in six to eight treatment sessions. The obtained results showed displacements of the external surface between different sessions up to 6.3 mm along a single direction, even at constant inspired volumes. The median value of the interfraction variability in the position of breast passive markers was 2.9 mm (range 1.9-4.8 mm) in the latero-lateral direction, 3.6 mm (range 2.2-4.6 mm) in the antero-posterior direction, and 4.3 mm (range 2.8-6.2 mm) in the cranio-caudal direction. There were no significant dose distribution variations for target and organs at risk with respect to the treatment plan, confirming the adequacy of the applied clinical margins (15 mm) to compensate for the measured setup uncertainties. This study demonstrates that spirometer-based control does not guarantee a stable and reproducible position of the external surface in left-breast DIBH radiotherapy, suggesting the need for more robust DIBH monitoring techniques when reduced margins and setup uncertainties are required for improving normal tissue sparing and decreasing cardiac and pulmonary toxicity.