脑胶质瘤患者术后放疗期间的瘤床体积变化及摆位误差的研究

摘要

Objective To observe and analyze factors that influence changes of the tumor bed volumes during the postoperative radi-ation therapy in patients with brain gliomas,and record set-up errors.Methods Eighteen patients with brain gliomas received postoperative radiation therapy at our institution,We delineated the boundaries of tumor bed (GTV-tb)in the planning CT and recorded the tumor bed vol-umes.Then,eighteen patients were divided into two groups to compare according to the different diameter of the tumor bed and edema.Cone-beam scan was performed weekly before treatment,the set-up errors were recorded from three directions:left-right,anterior-posterior,cranio-caudal.Results We received 18 sets of data on the changes of the tumor bed volumes,significant changes of the tumor bed volumes were ob-served in patients with larger tumor bed (measurable longest diameter>4 cm)and/or severe edema (required daily dehydration treatment). 108 sets of cone-beam CT images were obtained from the patients,The frequency of set-up errors more than 3 mm,4 mm,5 mm were 22,15 and 6,respectively.Conclusion Significant changes of tumor bed volumes were found in patients with larger tumor bed and/or severe ede-ma.The set-up errors in 98.1% patients were controlled within 5 mm,and we found the maximum set-up errors were in cranio-caudal direc-tion.%目的：观察分析脑胶质瘤患者术后放疗期间瘤床体积变化及其影响因素，并记录放疗期间的摆位误差。方法在18例脑胶质瘤患者术后放疗的计划CT中勾画出瘤床边界（GTV-tb）并记录瘤床体积，根据首次计划CT中可测量的瘤床最长径及水肿程度分组进行对比。每周行1次锥形束CT（CBCT）扫描，并记录摆位误差：左右方向（X1），上下方向（Y1），头脚方向（Z1）。结果共获得18组瘤床体积变化的数据，瘤床较大（可测量的最长径＞4 cm）和/或水肿程度较重（需日常脱水治疗）的患者的瘤床体积变化幅度比瘤床较小（最长径≤4 cm）且水肿较轻的患者大。CBCT扫描获得的108组共324个数据中，≤3 mm 281次，3 mm＜摆位误差≤4 mm 22次，4 mm＜摆位误差≤5 mm 15次，＞5 mm 6次。结论瘤床较大和/或水肿较重的患者的瘤床体积变化幅度较大，绝大部分脑胶质瘤术后放疗期间最大的摆位误差＜5 mm，其中头脚方向的摆位误差最大。