Department of Radiotherapy, Division of Radiation Physics, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, P.R. China.
Radiology Department, West China Hospital, Sichuan University, Chengdu 610041, P.R. China.
J Radiat Res. 2020 Nov 16;61(6):985-992. doi: 10.1093/jrr/rraa066.
To design a new breast vacuum bag to reduce global and local setup errors in post-mastectomy radiation therapy (PMRT). A total of 24 PMRT patients were immobilized with an old vacuum bag and 26 PMRT patients were immobilized with a new vacuum bag. The registration results were analysed using four regions of interest (ROI): the global ROI [including the whole region of the planning target volume (PTV), GROI], the supraclavicular area (SROI), the ipsilateral chest wall region (CROI) and the ipsilateral arm region (AROI). The global and local setup errors of the two groups were compared. The global setup errors of the new vacuum group were significantly smaller than those in the old vacuum group with the exception of yaw axes (P < 0.05). The systematic error (Σ) and random error (σ) ranged from 1.21 to 2.13 mm. In the new vacuum group, the local setup errors in the medial-lateral (ML) direction and roll axes for CROI (the Σ and σ ranged from 0.65 to 1.35 mm), and the local setup errors in ML and superior-inferior (SI) directions for SROI were significantly smaller than those in the old vacuum group. The total required PTV margins for the chest wall in ML, SI, and anterior-posterior (AP) were 4.40, 3.12 and 3.77 mm respectively. The new vacuum bag can significantly reduce the global setup errors and local setup errors in PMRT. The respiratory motion of the chest wall was negligible, and the 5 mm PTV margin could cover the local setup errors in PMRT using the new vacuum bag with cone beam CT (CBCT) correction.
为了设计一种新的乳房真空袋，以减少乳腺癌根治术后放射治疗（PMRT）中的全局和局部摆位误差。共有 24 名 PMRT 患者使用旧真空袋进行固定，26 名 PMRT 患者使用新真空袋进行固定。使用四个感兴趣区域（ROI）分析配准结果：全局 ROI（包括整个计划靶区（PTV）区域，GROI）、锁骨上区域（SROI）、同侧胸壁区域（CROI）和同侧手臂区域（AROI）。比较两组的全局和局部摆位误差。新真空组的全局摆位误差明显小于旧真空组，除了偏航轴（P < 0.05）。系统误差（Σ）和随机误差（σ）范围为 1.21 至 2.13 毫米。在新真空组中，CROI 的 ML 方向和滚转轴的局部摆位误差（Σ和σ范围为 0.65 至 1.35 毫米），以及 SROI 的 ML 和上下方向的局部摆位误差明显小于旧真空组。胸壁在 ML、SI 和 AP 方向的总 PTV 边缘要求分别为 4.40、3.12 和 3.77 毫米。新真空袋可显著降低 PMRT 的全局和局部摆位误差。胸壁的呼吸运动可以忽略不计，使用新真空袋和锥形束 CT（CBCT）校正，5 毫米的 PTV 边缘可以覆盖 PMRT 的局部摆位误差。
