Department of Radiation Oncology, The Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands.
Int J Radiat Oncol Biol Phys. 2013 Feb 1;85(2):536-42. doi: 10.1016/j.ijrobp.2012.04.004. Epub 2012 May 30.
To investigate the applicability of 3-dimensional (3D) surface imaging for image guidance in deep-inspiration breath-hold radiation therapy (DIBH-RT) for patients with left-sided breast cancer. For this purpose, setup data based on captured 3D surfaces was compared with setup data based on cone beam computed tomography (CBCT).
Twenty patients treated with DIBH-RT after breast-conserving surgery (BCS) were included. Before the start of treatment, each patient underwent a breath-hold CT scan for planning purposes. During treatment, dose delivery was preceded by setup verification using CBCT of the left breast. 3D surfaces were captured by a surface imaging system concurrently with the CBCT scan. Retrospectively, surface registrations were performed for CBCT to CT and for a captured 3D surface to CT. The resulting setup errors were compared with linear regression analysis. For the differences between setup errors, group mean, systematic error, random error, and 95% limits of agreement were calculated. Furthermore, receiver operating characteristic (ROC) analysis was performed.
Good correlation between setup errors was found: R(2)=0.70, 0.90, 0.82 in left-right, craniocaudal, and anterior-posterior directions, respectively. Systematic errors were ≤0.17 cm in all directions. Random errors were ≤0.15 cm. The limits of agreement were -0.34-0.48, -0.42-0.39, and -0.52-0.23 cm in left-right, craniocaudal, and anterior-posterior directions, respectively. ROC analysis showed that a threshold between 0.4 and 0.8 cm corresponds to promising true positive rates (0.78-0.95) and false positive rates (0.12-0.28).
The results support the application of 3D surface imaging for image guidance in DIBH-RT after BCS.
研究 3 维（3D）表面成像在左侧乳腺癌深吸气屏气放疗（DIBH-RT）中的图像引导适用性。为此，将基于捕获的 3D 表面的设置数据与基于锥形束 CT（CBCT）的设置数据进行了比较。
共纳入 20 例接受保乳手术后 DIBH-RT 的患者。在开始治疗前，每位患者均进行屏气 CT 扫描以进行计划。在治疗过程中，在使用左乳 CBCT 进行设置验证后，开始进行剂量输送。同时使用表面成像系统对 CBCT 进行了 3D 表面捕获。回顾性地，对 CBCT 与 CT 以及捕获的 3D 表面与 CT 进行了表面配准。通过线性回归分析比较了由此产生的设置误差。对于设置误差的差异，计算了组平均值、系统误差、随机误差和 95%的一致性界限。此外，还进行了接收者操作特征（ROC）分析。
发现设置误差之间具有良好的相关性：左右、头脚和前后方向的 R2 值分别为 0.70、0.90 和 0.82。所有方向的系统误差均≤0.17cm。随机误差均≤0.15cm。左右、头脚和前后方向的一致性界限分别为-0.34-0.48、-0.42-0.39 和-0.52-0.23cm。ROC 分析表明，阈值在 0.4 到 0.8cm 之间对应于有希望的真阳性率（0.78-0.95）和假阳性率（0.12-0.28）。
结果支持在 BCS 后 DIBH-RT 中使用 3D 表面成像进行图像引导。
