Department of Radiation Oncology and Image-Applied Therapy, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, Kyoto, 606-8507, Japan.
Division of Clinical Radiology Service, Kyoto University Hospital, Kyoto, Japan.
Radiat Oncol. 2021 Mar 6;16(1):49. doi: 10.1186/s13014-021-01777-7.
This study aimed to quantify errors by using a cine electronic portal imaging device (cine EPID) during deep inspiration breath-hold (DIBH) for left-sided breast cancer and to estimate the planning target volume (PTV) by variance component analysis.
This study included 25 consecutive left-sided breast cancer patients treated with whole-breast irradiation (WBI) using DIBH. Breath-holding was performed while monitoring abdominal anterior-posterior (AP) motion using the Real-time Position Management (RPM) system. Cine EPID was used to evaluate the chest wall displacements in patients. Cine EPID images of the patients (309,609 frames) were analyzed to detect the edges of the chest wall using a Canny filter. The errors that occurred during DIBH included differences between the chest wall position detected by digitally reconstructed radiographs and that of all cine EPID images. The inter-patient, inter-fraction, and intra-fractional standard deviations (SDs) in the DIBH were calculated, and the PTV margin was estimated by variance component analysis.
The median patient age was 55 (35-79) years, and the mean irradiation time was 20.4 ± 1.7 s. The abdominal AP motion was 1.36 ± 0.94 (0.14-5.28) mm. The overall mean of the errors was 0.30 mm (95% confidence interval: - 0.05-0.65). The inter-patient, inter-fraction, and intra-fractional SDs in the DIBH were 0.82 mm, 1.19 mm, and 1.63 mm, respectively, and the PTV margin was calculated as 3.59 mm.
Errors during DIBH for breast radiotherapy were monitored using EPID images and appropriate PTV margins were estimated by variance component analysis.
本研究旨在通过使用电影式电子射野影像装置（cine EPID）量化深吸气屏气（DIBH）左侧乳腺癌过程中的误差，并通过方差分量分析估算计划靶区（PTV）。
本研究纳入了 25 例接受 DIBH 全乳照射（WBI）的左侧乳腺癌连续患者。通过实时位置管理（RPM）系统监测腹部前后（AP）运动进行屏气。cine EPID 用于评估患者的胸壁位移。分析患者的 cine EPID 图像（309609 帧），使用 Canny 滤波器检测胸壁边缘。DIBH 期间发生的误差包括数字重建射线照相术检测到的胸壁位置与所有 cine EPID 图像之间的差异。计算了 DIBH 中的患者间、分次间和分次内标准差（SD），并通过方差分量分析估算了 PTV 边界。
患者的中位年龄为 55 岁（35-79 岁），平均照射时间为 20.4±1.7s。腹部 AP 运动为 1.36±0.94（0.14-5.28）mm。误差的总体平均值为 0.30mm（95%置信区间：-0.05-0.65）。DIBH 中的患者间、分次间和分次内 SD 分别为 0.82mm、1.19mm 和 1.63mm，PTV 边界计算为 3.59mm。
通过 EPID 图像监测了乳腺癌放疗期间 DIBH 的误差，并通过方差分量分析估算了适当的 PTV 边界。
