中国癌症杂志2025，Vol.35Issue(8)：752-760,9.DOI:10.19401/j.cnki.1007-3639.2025.08.003
基于每日CBCT的乳腺癌术后单周超大分割全乳放疗的位置误差及外扩边界研究
Set-up error and CTV margin in one-week ultra-hypofractionated whole breast irradiation after breast-conserving surgery based on daily CBCT
摘要
Abstract
Background and purpose:Single-week ultra-hypofractionated whole breast irradiation(WBI)after breast-conserving surgery could shorten the treatment duration while ensuring efficacy and safety,making it a viable option for WBI.However,ultra-hypofractionated WBI requires daily image-guided radiotherapy(IGRT),and its impact on setup errors remains unclear.This study aimed to identify factors associated with set-up errors in ultra-hypofractionated WBI guided with daily cone-beam computed tomography(CBCT)and calculate margin expanded from clinical target volume(CTV)to planning target volume(PTV).Methods:This study included patients enrolled in a prospective trial that explored the safety of single-week ultra-hypofractionated WBI(NCT04926766)in Shanghai Ruijin Hospital,which was approved by Shanghai Ruijin Hospital Ethics Committee(No.2020-352).All patients received CBCT1 after positioning.After correcting errors,patients received CBCT2.CBCT3 was conducted after radiotherapy was completed.The translational errors between CBCT1,CBCT2,and plan CT were initial and residual inter-fractional errors.The translational error between CBCT2 and CBCT3 was an intra-fractional error.The PTV margin was calculated according to the van Herk formula.Results:A total of 34 patients were enrolled in this study,and 510 CBCT images were collected.Daily CBCT significantly reduced set-up error in anterior-posterior(AP),superior-inferior(SI)and right-left(RL)directions(initial inter-fractional error vs residual inter-fractional error:AP,2.8 mm vs 0.4 mm;SI,1.6 mm vs 0.5 mm;RL,1.8 mm vs 0.3 mm,all P＜0.001).Higher CTV volume(＞402.5 cm3 vs≤402.5 cm3)was associated with larger residual inter-fractional error(0.5 mm vs 0.3 mm,P=0.023)and intra-fractional error(0.5 mm vs 0.2 mm,P=0.001)in AP direction.Higher CTV volume was also associated with larger residual inter-fractional error in the SI direction(0.6 mm vs 0.5 mm,P=0.037).Higher BMI(＞23.2 kg/m2 vs≤23.2 kg/m2)and larger weight(＞60.0 kg vs≤60.0 kg)were associated with larger intra-fractional error in AP direction:0.7 mm vs 0.2 mm(P＜0.001)and 0.5 mm vs 0.2 mm(P=0.033),respectively.Under guidance with daily CBCT,the recommended margins were 2.3 mm in AP direction,2.8 mm in SI direction,and 2.0 mm in RL direction.However,in patients with CTV volume＞402.5 cm3 and BMI＞23.2 kg/m2,a larger margin was recommended in SI direction:3.1 mm and 3.4 mm,respectively.Conclusion:The 3 mm margin was feasible under guidance with daily CBCT.The CTV to PTV margin should be larger in patients with higher BMI or CTV volume.关键词
乳腺癌/单周超大分割放疗/全乳放疗/位置误差/外扩边界Key words
Breast cancer/Ultra-hypofractionated radiotherapy/Whole breast irradiation/Set-up error/Margin分类
医药卫生引用本文复制引用
王孟潇,樊文栋,曹菁璟,陈佳艺,蔡钢,曹璐..基于每日CBCT的乳腺癌术后单周超大分割全乳放疗的位置误差及外扩边界研究[J].中国癌症杂志,2025,35(8):752-760,9.基金项目
上海市卫生健康委员会卫生行业临床研究专项(20224Y0025),国家科技四大慢病重大专项(2023ZD0502200,2023ZD0502206). Shanghai Municipal Health Commission's Special Program for Clinical Research in the Health Sector(20224Y0025), National Science and Technology Major Project for the Four Major Chronic Diseases (2023ZD0502200,2023ZD0502206). （20224Y0025）
