发泡胶固定的乳腺癌放疗摆位误差和计划靶区体积范围  

Setup error and planning target volume boundary in foam-immobilized radiotherapy for breast cancer

作　　者：成媛 李政欢 陈宥霖 李素玉[2] CHENG Yuan;LI Zhenghuan;CHEN Youlin;LI Suyu(Fuzhou No.1 Hospital Affiliated with Fujian Medical University,Fuzhou 350000,China;Fujian Maternity and Child Health Hospital,Fuzhou 350005,China;The Third Affiliated Hospital of Sun Yat-sen University,Guangzhou 510630,China)

机构地区：[1]福建医科大学附属福州市第一医院,福州350000 [2]福建省妇幼保健院,福州350005 [3]中山大学附属第三医院,广州510630

出　　处：《辐射研究与辐射工艺学报》2022年第5期32-40,共9页Journal of Radiation Research and Radiation Processing

基　　金：福建省中青年骨干人才培养项目(2019-ZQN-23)。

摘　　要：乳腺癌放疗误差主要由摆位误差和呼吸运动组成,通过准确测量摆位误差为乳腺癌计划靶区体积(PTV)外扩范围提供临床参考依据,提高治疗精度。测量2021年6月至10月采用发泡胶固定的31例乳腺癌患者的摆位误差。每一例患者在治疗前三次以及治疗后的每周进行一次锥形束CT(CBCT)扫描,将获取的CBCT图像与治疗计划CT进行骨性配准,并记录配准结果得到摆位误差值,分析摆位误差,并据此计算PTV外放边界的大小。结果显示:31例患者共行131次CBCT扫描,X(左右)、Y(头脚)和Z(腹背)方向的系统误差和随机误差的标准差分别是1.40 mm和0.67 mm、1.89 mm和0.56 mm、1.68 mm和1.16 mm;摆位误差的绝对值最大分别为4.9 mm、6.4 mm、8.7 mm;5.0 mm内误差在X、Y、Z方向分别占100%、98.47%、93.89%;X、Y、Z方向摆位误差小于3 mm的发生率分别为88.55%、79.39%、75.57%。经公式计算,得到本科室治疗乳腺癌临床靶区体积(CTV)到PTV外扩理论边界三个方向分别为3.98 mm、5.11 mm、5.02 mm。结果提示:发泡胶固定的乳腺癌调强放疗中,基于经验PTV外放边界的大小不能准确反映实际的摆位误差,需要基于CBCT测量和分析摆位误差、计算PTV外扩边界、指导临床靶区勾画范围具有实际的临床意义。Radiotherapy error in breast cancer mainly comprises setup error and respiratory breast motion.An accurate measurement of the setup error can provide a clinical reference for breast cancer planning target volume(PTV)expansion and improve treatment accuracy.Setup error rates were measured in 31 patients with breast cancer who underwent im-age-guided radiotherapy between June and October 2021.Cone beam computed tomography(CBCT)was performed for each patient first three times of treatment,and then once a week until the end of treatment.Bone registration was performed between the CBCT images and the CT images of the treatment plan.Record the registration results and obtain the setup errors.Calculated the external boundary of the PTV according to the setup error.A total of 131 CBCT scans were obtained for 31 patients.The standard deviation of systematic error and random error on the X(left and right),Y(the head and foot),and Z(the abdomen and back)axes were 1.40 and0.67 mm,1.89 and 0.56 mm,and 1.68 and 1.16 mm,respectively.The maximum absolute values of the setup errors were 4.9 mm,6.4 mm,and 8.7 mm,respectively.The errors within 5.0 mm accounted for 100%,98.47%,and93.89%,respectively.The incidence of setup errors<3 mm on the X,Y,and Z axes were 88.55%,79.39%,and75.57%,respectively.Based on the outward expansion of the clinical target volume,the PTV theoretical boundaries of breast cancer were 3.98 mm,5.11 mm,and 5.02 mm,respectively.In foam-immobilized radiotherapy for breast cancer,the actual setup error cannot be accurately reflected considering the empirical PTV external boundary.It is clinically significant to measure and analyze the setup error using CBCT to calculate the PTV external boundary and guide clinical target area delineation.

关 键 词：乳腺癌 发泡胶 调强放射治疗 摆位误差 外扩边界 

分 类 号：R815[医药卫生—放射医学]