Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas.
Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas.
Pract Radiat Oncol. 2011 Apr-Jun;1(2):97-104. doi: 10.1016/j.prro.2010.10.003. Epub 2011 Apr 8.
Consistency in defining and contouring target structures in radiation therapy (RT) is critical for highly conformal RT, for evaluating treatment plans, and for quality assurance in multi-institutional RT trials. The Radiation Therapy Oncology Group (RTOG) has published consensus guidelines for contouring targets for postmastectomy RT. To aid in contouring such structures, we evaluated the potential use of an automated contouring technique, known as deformable image registration-based breast segmentation (DEF-SEG).
The RTOG definitions were used to contour the chest wall (CW); levels I, II, and III axillary nodes (Ax1, Ax2, Ax3); supraclavicular (SCV) nodes; internal mammary (IM) nodes; and the heart. Left-sided and right-sided templates were created. The DEF-SEG was then used to generate auto-segmented contours from the appropriate template to computed tomographic scans of 20 test cases (10 left, 10 right). To assess the accuracy of this method, those contours were manually modified as necessary to match the RTOG definitions, and the extent of the overlap was compared. The dosimetric impact of the difference in contours was then evaluated by comparing dose-volume histograms for modified and unmodified contours.
Mean volume-overlap ratios between the unmodified DEF-SEG-generated contours and modified contours were as follows: CW, 0.91; Ax1, 0.68; Ax2, 0.64; Ax3, 0.68; SCV node, 0.66; IM node, 0.32, and the heart, 0.93. Mean differences in volume receiving 45 Gy (V45) for the modified versus unmodified contours were as follows: CW, 2.1%; SCV node, 4.8%; Ax1, 5.1%; Ax2, 5.6%; Ax3, 3.0%; and IM node, 10.1%. Mean differences in V10 between the modified heart and the unmodified heart were 0.4% for right-sided treatment and 0.5% for left-sided treatment.
The DEF-SEG can be helpful for delineating structures according to the RTOG consensus guidelines, particularly for the CW and the heart. No clinically significant dosimetric differences were found between the modified and unmodified contours. The DEF-SEG may be useful for evaluating treatment plans for postmastectomy RT in multi-institutional trials.
在高度适形放疗、评估治疗计划和多机构放疗试验的质量保证中，放射治疗（RT）中靶结构的定义和勾画的一致性至关重要。放射治疗肿瘤学组（RTOG）已经发布了用于勾画乳腺癌根治术后放疗靶区的共识指南。为了帮助勾画这些结构，我们评估了一种自动勾画技术的潜在用途，即基于变形图像配准的乳房分割（DEF-SEG）。
使用 RTOG 定义来勾画胸壁（CW）；Ⅰ、Ⅱ和Ⅲ腋窝淋巴结（Ax1、Ax2、Ax3）；锁骨上（SCV）淋巴结；内乳淋巴结（IM）；和心脏。创建了左侧和右侧模板。然后，将 DEF-SEG 用于从适当的模板生成自动分割轮廓，以匹配 20 个测试病例的计算机断层扫描（10 个左侧，10 个右侧）。为了评估该方法的准确性，必要时手动修改这些轮廓以匹配 RTOG 定义，并比较重叠的程度。然后通过比较修改和未修改轮廓的剂量-体积直方图来评估轮廓差异的剂量学影响。
未修改的 DEF-SEG 生成的轮廓与修改后的轮廓之间的平均体积重叠比如下：CW，0.91；Ax1，0.68；Ax2，0.64；Ax3，0.68；SCV 节点，0.66；IM 节点，0.32，和心脏，0.93。修改后的轮廓与未修改的轮廓相比，体积接受 45 Gy（V45）的平均差异如下：CW，2.1%；SCV 节点，4.8%；Ax1，5.1%；Ax2，5.6%；Ax3，3.0%；和 IM 节点，10.1%。修改后的心脏与未修改的心脏之间 V10 的平均差异分别为右侧治疗的 0.4%和左侧治疗的 0.5%。
DEF-SEG 可有助于根据 RTOG 共识指南勾画结构，特别是对于 CW 和心脏。在修改后的轮廓和未修改的轮廓之间未发现临床意义上的剂量学差异。DEF-SEG 可用于评估多机构乳腺癌根治术后放疗试验的治疗计划。
