基于4DCBCT定位和引导评估中下叶肺癌放疗内靶区ITV的投照准确性  

4D cone beam CT based radiotherapy target accuracy in stereotactic body radiotherapy for lung tumor in the middle or lower lobe

作　　者：李毅[1] 吴文婧[2] 惠蓓娜[1] 张月美 王尧 张晓智[1] LI Yi;WU Wenjing;HUI Beina;ZHANG Yuemei;WANG Yao;ZHANG Xiaozhi(Department of Radiation Oncology, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an 710061;Xi’an Center for Disease Control and Prevention, Xi’an 710054, China)

机构地区：[1]西安交通大学第一附属医院肿瘤放疗科,陕西西安710061 [2]西安市疾病预防控制中心,陕西西安710054

出　　处：《西安交通大学学报（医学版）》2021年第3期438-442,共5页Journal of Xi’an Jiaotong University（Medical Sciences）

基　　金：西安交通大学第一附属医院面上项目(No.XJTU1 AF-CRF-2018MS-25)。

摘　　要：目的通过四维锥形束CT(four-dimensional cone beam computed tomography,4DCBCT)在线校正肺中下叶肿瘤立体定向放射治疗(stereotactic body radiation therapy,SBRT)放疗靶区摆位差和呼吸运动偏差,利用校正后的摆位和呼吸运动残余误差确定肿瘤内靶区体积(internal target volume,ITV)外放边界大小。方法回顾性分析20例肺中下叶肿瘤SBRT治疗患者,热塑体膜固定体位,4DCBCT定位确定治疗位置ITV。每次治疗前扫描4DCBCT,共76次扫描图像,根据4DCBCT与定位CT的配准结果,校正摆位误差和呼吸运动误差,获取校正后的分次间摆位残差和呼吸运动残差,确定ITV外放边界大小。结果4DCBCT校正后,放疗靶区摆位误差和呼吸运动误差明显减小。放疗靶区摆位残差在左右、上下、前后3个方向上分别为(0.07±0.12)cm、(0.03±0.29)cm和(0.04±0.14)cm,放疗靶区呼吸运动残差在3个方向上分别为(-0.06±0.07)cm、(0.02±0.26)cm和(0.02±0.11)cm。经过4DCBCT校正,利用VanHerk公式计算的PTV外放边界在3个方向上由1.13、2.15、0.90 cm减小到0.50、0.59、0.56 cm。结论对于肺中下叶肿瘤的SBRT治疗,4DCBCT校正后的放疗靶区摆位残差和呼吸运动残差不可忽略。由4DCBCT确定治疗位置的ITV需均匀外放0.6 cm,保证放疗靶区准确投照的同时,减少正常组织受照的体积。Objective To investigate setup and respiratory movement residual error with the guidance of online four-dimensional cone beam computed tomography(4DCBCT)and the impact on margins required to internal target volume(ITV)margin during stereotactic body radiotherapy(SBRT)of lung tumor in the middle or lower lobe.Methods Twenty SBRT treatment patients with lung tumor in the middle or lower lobe were enrolled for treatment residual error retrospective analysis.Thermoplastic masks were used as immobilization devices during SBRT treatment.ITV was determined by 4DCBCT simulation.A total of 764DCBCT scans before the treatment were recorded to determine the setup and respiratory residual error for ITV margins.Results The setup and respiratory movement error were significantly reduced with the guidance of online 4DCBCT during radiotherapy.The setup residual errors were respectively(0.07±0.12)cm,(0.03±0.29)cm and(0.04±0.14)cm in right-left(RL),superior-inferior(SI)directions and anterior-posterior(AP)directions.The respiratory movement residual errors were respectively(-0.06±0.07)cm,(0.02±0.26)cm and(0.02±0.11)cm in RL,AP,and SI directions.Based on setup and respiratory movement residual errors,the PTV margins of NSCLC were reduced from 1.13 cm,2.15 cm and 0.90 cm to 0.50 cm,0.59 cm and 0.56 cm in RL,AP and SI directions,respectively,calculated with recipe by VanHerk.Conclusion With the guidance of online 4DCBCT,the setup and respiratory movement residual error cannot be ignored during SBRT of lung tumor in the middle or lower lobe.The ITV margin requiredafter online 4DCBCT correction for the patients enrolled in the study would be approximatively 0.6 cm around to ensure an accurate dose to the target tumor and reduce the dose to normal tissues.

关 键 词：肺中下叶肿瘤 SBRT 4DCBCT ITV外放边界 

分 类 号：R734.2[医药卫生—肿瘤] R815[医药卫生—临床医学]