肿瘤预防与治疗2024，Vol.37Issue(10)：898-903,6.DOI:10.3969/j.issn.1674-0904.2024.10.009
中下肺肿瘤SBRT放疗中分次内误差影响因素以及PTV外扩边界分析
Analysis of PTV Margins and Influencing Factors of Intra-fraction Errors in SBRT for Middle and Lower Lung Tumors
摘要
Abstract
Objective:To explore the influencing factors of intra-fraction errors in SBRT radiotherapy for middle and lower lung tumors and calculate the PTV margins(PM).Methods:We collected 21 patients who underwent stereotactic body ra-diotherapy(SBRT)for middle and lower lung tumors in the Oncology Department of Deyang People's Hospital from February 2022 to June 2023.They were in a supine position with both hands raising to hold the grab bar,and their heads,necks and chests were fixed with thermoplastic membrane.Three dimensional computed tomography(3D-CT)and four-dimensional cone beam computed tomography(4D-CBCT)were used to locate the tumors and determine internal target volume(ITV),with the total dose in fractionation mode of 48～60 Gy and a single fraction of6～12 Gy(a total of4～10 fractions).Patients were scanned with three dimensional cone beam computed tomography(3D-CBCT)before treatment,the couch was moved to correct the positioning errors before starting treatment.After that,another 3D-CBCT scan was performed and the errors were recorded as the intra-fraction errors.The vector dis-tance of the intra-fraction error was calculated and analyzed its correlation to treatment time,body mass index(BM1)and pa-tient age were analyzed.The errors in two times of 3D-CBCT were recorded,and the PM required for inter-fraction and intra-fraction errors were calculated using the PM formula.Statistical analysis was performed using SPSS 26.0.Results:The mean vector distance of intra-fraction errors in three-dimensional directions was(0.17±0.16)cm,significantly correlated to treatment time(r=0.38,P＜0.01);not correlated to patient age(r=-0.09,P=0.33);and not correlated to BMI(r=0.18,P=0.06).The inter-fraction and intra-fraction errors in left-right(LR)direction were(-0.08±0.26)cm and(-0.01±0.10)cm,those in superior-inferior(SI)direction were(-0.1±0.36)cm and(-0.01±0.15)cm,and those in anterior-posterior(AP)direction(-0.05±0.17)cm and(0.02±0.14)cm,respectively.The PM required for inter-fraction and intra-fraction errors in LR,SI and AP directions were 0.54 cm vs 0.11 cm,0.78 cm vs 0.16 cm,and 0.31 cm vs 0.14 cm,respectively.Conclusion:Intra-fraction errors in SBRT radiotherapy for middle and lower lung cancer were correlated to treatment time,but correlated to neither age nor BMI of patients.In the treatment of middle and lower lung cancer by SBRT,0.5 cm PM can compensate for the position changes caused by intra-fraction errors after using 4D-CBCT-assisted ITV delineation.关键词
3D-CBCT/分次内误差/SBRT/中下肺肿瘤/BMI/PTV-marginKey words
3D-CBCT/Intra-fraction error/SBRT/Middle and lower lung cancer/BMI/PTV margin分类
医药卫生引用本文复制引用
曾伟,叶程伟,刘莉,袁建军,罗志尧,刘江,刘娜,何淼..中下肺肿瘤SBRT放疗中分次内误差影响因素以及PTV外扩边界分析[J].肿瘤预防与治疗,2024,37(10):898-903,6.基金项目
德阳市科技局重点研发项目(编号:2021SZ008) （编号:2021SZ008）
四川省护理职业学院自然科学课题(编号:2023ZRY27) This study was supported by grants from Deyang Science and Technology Bureau(No.2021SZ008)and Sichuan Nursing Vocational College(No.2023ZRY27). （编号:2023ZRY27）
