Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan; Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, Higashihiroshima, Japan.
Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan; Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, Higashihiroshima, Japan.
Med Dosim. 2020;45(3):252-255. doi: 10.1016/j.meddos.2020.01.003. Epub 2020 Feb 13.
Tumor geometric reproducibility for lung stereotactic body radiotherapy (SBRT) is an important issue in the breath-hold (BH) technique. We investigated the inter-BH reproducibility of the tumor position in expiratory BH using our proposed vector volume histogram (VVH) method. Subjects comprising 14 patients with lung cancer who were treated with lung SBRT under expiratory BH conditions were monitored by the Abches system. Multiple computed tomography (CT) scans were performed to evaluate the inter-BH reproducibility of the tumor position at the expiratory BH in the simulation session. Gross tumor volume was delineated by a physician. Deformable image registration was used to deform the images from the 3 expiratory BH-CTs to the treatment planning expiratory BH-CT. To evaluate the inter-BH reproducibility of the tumor positions, we measured the largest motion extent within the organ of 3 dimensions (left-right, LR; anterior-posterior, AP; cranio-caudal, CC) and a 3D vector using the VVH method. The average and standard deviations of the inter-BH reproducibility of the tumor position in the LR, AP, and CC directions, and the 3D vector were 1.7 ± 0.5, 2.0 ± 0.7, 2.1 ± 0.7, and 2.7 ± 0.7 mm, respectively. Ten patients exhibited inter-BH displacements of the lung tumor >3 mm in the 3D vector. No displacement >5 mm was observed in any direction for all patients. Our study indicated that the inter-BH variation of the tumor position was small for lung cancer patients, using the Abches system and the VVH method.
对于肺部立体定向体放射治疗（SBRT）来说，肿瘤的几何可重复性是屏气（BH）技术中的一个重要问题。我们利用我们提出的矢量体积直方图（VVH）方法，研究了呼气 BH 中肿瘤位置的 BH 间可重复性。对 14 名接受肺部 SBRT 治疗的肺癌患者进行了监测，这些患者在呼气 BH 条件下接受治疗。在模拟阶段进行了多次计算机断层扫描（CT），以评估呼气 BH 中肿瘤位置的 BH 间可重复性。由医生勾画大体肿瘤体积。使用变形图像配准将 3 次呼气 BH-CT 图像变形到治疗计划呼气 BH-CT。为了评估肿瘤位置的 BH 间可重复性，我们使用 VVH 方法测量了 3 个维度（左右 LR；前后 AP；头脚 CC）和 3D 向量中器官内的最大运动幅度。肿瘤位置在 LR、AP 和 CC 方向以及 3D 向量中的 BH 间可重复性的平均值和标准差分别为 1.7 ± 0.5、2.0 ± 0.7、2.1 ± 0.7 和 2.7 ± 0.7mm。10 名患者的 3D 向量中肿瘤的 BH 间位移大于 3mm。所有患者在任何方向均未观察到大于 5mm 的位移。我们的研究表明，使用 Abches 系统和 VVH 方法，肺癌患者的肿瘤位置 BH 间变化较小。
