胸段食管癌动态调强IGRT分次摆位误差对剂量学的影响  

Effect of Fractional Setup Error of Image-Guided Radiotherapy Dynamic Intensity Modulation on Dosimetry in Thoracic Esophageal Carcinoma

作　　者：徐晓捷 雷亚楠 张瑞英[1] 贾雪丽 侯鹏 李敬霞[1] XU Xiao-jie;LEI Ya-nan;ZHANG Rui-ying;JIA Xue-li;HOU Peng;LI Jing-xia(The First Affiliated Hospital,and College of Clinical Medicine of Henan University of Science and Technology,Luoyang,China,471003)

机构地区：[1]河南科技大学临床医学院,河南科技大学第一附属医院,中国洛阳471003

出　　处：《食管疾病》2021年第2期85-88,共4页Journal of Esophageal Diseases

摘　　要：目的用CBCT测量胸段食管癌动态调强放疗中的分次摆位误差,评价摆位误差对靶区和危及器官剂量的影响。方法应用CBCT采集31例胸段食管癌患者的摆位误差,获取518组修正前的摆位误差。根据每例患者误差值模拟出治疗计划2,与原始计划1进行比较,分析摆位误差对靶区和周围正常器官受照剂量的影响。结果胸段食管癌动态调强IGRT分次间的摆位误差在左右(x轴)方向、上下(y轴)方向、前后(z轴)方向的摆位误差分别为(1.98±1.80)、(4.62±4.02)和(1.52±1.16)mm。摆位误差对肿瘤区GTV的剂量分布影响不大,但使PTV的最小剂量(D min)减少918 cGy且有统计学差异(t=3.28,P<0.05),PTV的平均剂量(D mean)减少了149 cGy;摆位误差对PTV的适形度指数CI、均匀性指数HI,以及肺、心脏等周围正常器官受照剂量影响不大;模拟计划中脊髓的最大剂量(D max)的平均值高了284 cGy,其中10例脊髓受量超过4500 cGy,有1例最大值达到5307.60 cGy。结论图像引导的分次间的摆位误差对靶区和危及器官剂量分布有一定影响,分次摆位误差可能会导致脊髓的受照剂量超过最大耐受值。Objective To measure the setup errors in thoracic esophageal carcinoma treated with dynamic intensity modulated radiotherapy using cone-beam CT(CBCT)and to evaluate the effect of setup errors on the dose distributions in tumor target volume and the surrounding normal tissues.Methods The setup errors of 31 patients with thoracic esophageal carcinoma were collected by CBCT and 518 setup errors of these patients were acquired before treatment.The treatment plan was simulated according to the error value of each patient.Compared with the original plan,the influence of setup error on the radiation dose of target area and surrounding normal organs was analyzed.Results The setup errors of dynamic intensity modulation IGRT for thoracic esophageal cancer were(1.98±1.80)(x-axis),(4.62±4.02)(y-axis),and(1.52±1.16)(z-axis),respectively.The dose distribution of gross tumor volume(GTV)in tumor area was not affected by setup errors.However,the minimal dose(D min)of PTV decreased by 918 cGy(t=3.28,P<0.05),and the mean dose(D mean)of PTV decreased by 149 cGy.The setup errors have little influence on the conformity index(CI)and homogeneity index(HI)for PTV.No statistical significance was observed in the dose differences in normal surrounding organs such as left lung,right lung and heart.The mean maximum dose(D max)of the spinal cord in the simulation plan increased 284 cGy.For 10 patients,the maximum dose of the spinal cord exceeded 4500 cGy in the simulation plan,and even reached 5307.60 cGy in one case.Conclusion The dose distribution of the target volume and organs at risk were influenced by setup errors of IGRT in part,especially for the spinal cord.The setup errors may lead the radiation dose of spinal cord to exceed the maximum tolerance value for some patients.

关 键 词：食管癌 CBCT 摆位误差 剂量学 

分 类 号：R735.1[医药卫生—肿瘤]