Ruan Junjie, Huang Xiaotong, Wang Tong, Mai Xiuying, Lin Chuyan, Li Fanghua, Li Yunfeng, Chi Feng, Li Bin
State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China.
J Appl Clin Med Phys. 2025 Mar;26(3):e14573. doi: 10.1002/acm2.14573. Epub 2024 Nov 29.
The objective of this study is to evaluate the impact of different belly board and daily changes in patient's body-mass factor (BMF) on setup displacement in radiotherapy for rectal cancer.
Twenty-five patients were immobilized using the thermoplastic mask with belly board (TM-BB), and 30 used the vacuum bag cushion with belly board (VBC-BB), performing daily cone-beam computed tomography (CBCT) scans 625 times and 750 times, respectively. Daily pretreatment CBCT scans were registered to the planned CT images for BMF change determination and setup displacement measurement. Independent t-tests compared setup displacement between the two groups in left-right (LR), superior-inferior (SI), and anterior-posterior (AP) directions, as well as the BMF changes. The impact of daily BMF changes on setup displacement was evaluated using multivariate logistic regression and 10-fold cross-validation.
The setup displacement for TM-BB in the LR, SI, and AP directions were 0.31 ± 0.25, 0.58 ± 0.40, and 0.19 ± 0.18 cm, respectively, while VBC-BB showed 0.19 ± 0.15, 0.26 ± 0.22, and 0.36 ± 0.29 cm in the corresponding directions, respectively. Margins of planning target volume (PTV) for TM-BB were 8, 10, and 6 mm in LR, SI, and AP directions, while VBC-BB showed margins of 5,7, and 8 mm, respectively. The daily BMF changes for both groups were ranked in descending order as follows: sacral rotation angle (RS), hip lateral diameter (HLD), and hip anterior-posterior diameter (HAPD). HAPD was the main factor affecting setup displacement in both the AP and SI directions in TM-BB, while RS was the primary factor for setup displacement in the AP direction in VBC-BB.
Compared with TM-BB, VBC-BB had a larger AP displacement but smaller in LR and SI displacement. Daily changes in BMF have distinct effects on setup displacement in different immobilization devices. Image-guided radiation therapy (IGRT) is highly recommended and BMF changes should be given consideration during radiotherapy.
本研究旨在评估不同的腹托以及患者身体质量因子（BMF）的每日变化对直肠癌放疗中摆位位移的影响。
25例患者使用带有腹托的热塑性面罩（TM-BB）进行固定，30例患者使用带有腹托的真空袋垫（VBC-BB）进行固定，分别进行了625次和750次每日锥形束计算机断层扫描（CBCT）。将每日治疗前的CBCT扫描图像与计划CT图像配准，以确定BMF变化并测量摆位位移。采用独立t检验比较两组在左右（LR）、上下（SI）和前后（AP）方向上的摆位位移以及BMF变化。使用多变量逻辑回归和10折交叉验证评估每日BMF变化对摆位位移的影响。
TM-BB在LR、SI和AP方向上的摆位位移分别为0.31±0.25、0.58±0.40和0.19±0.18 cm，而VBC-BB在相应方向上分别为0.19±0.15、0.26±0.22和0.36±0.29 cm。TM-BB的计划靶区（PTV）在LR、SI和AP方向上的边界分别为8、10和6 mm，而VBC-BB的边界分别为5、7和8 mm。两组的每日BMF变化按降序排列如下：骶骨旋转角度（RS）、髋部外侧直径（HLD）和髋部前后直径（HAPD）。HAPD是影响TM-BB在AP和SI方向上摆位位移的主要因素，而RS是VBC-BB在AP方向上摆位位移的主要因素。
与TM-BB相比，VBC-BB的AP位移较大，但LR和SI位移较小。BMF的每日变化对不同固定装置中的摆位位移有不同影响。强烈建议采用图像引导放射治疗（IGRT），并且在放疗期间应考虑BMF变化。
