锥形束CT在鼻咽癌调强放疗中摆位误差情况及对靶区、邻近器官剂量的影响分析  

Setup Errors of Cone Beam CT in Intensity Modulated Radiotherapy for Nasopharyngeal Carcinoma and Its Influences on Target Volume and Adjacent Organ Dose

作　　者：冯凯华[1] 玉贵永 邹良群[1] FENG Kai-hua;YU Gui-yong;ZOU Liang-qun(Department of Radiotherapy,Affiliated Hospital of Guilin Medical College,Guilin 541001,Guangxi Zhuang Autonomous Region,China)

机构地区：[1]桂林医学院附属医院放疗科,广西桂林541001

出　　处：《中国CT和MRI杂志》2022年第5期7-9,共3页Chinese Journal of CT and MRI

摘　　要：目的 观察锥形束CT(CBCT)在鼻咽癌调强放疗中摆位误差情况及对靶区、邻近器官剂量的影响。方法 选取2017年6月至2020年6月在我院行调强放射治疗的鼻咽癌患者120例,采用CBCT系统获取CBCT图像,在摆位前、在线修正后及治疗结束后的获取CT实际图像,比较摆位前、在线修正后及治疗结束后的的摆位误差及偏差≤2mm的人数比例;比较各靶区实际剂量与计划剂量及放疗前、放疗中期原发肿瘤大体瘤体积(GTVnx)、转移淋巴结大体肿瘤体积(GTVnd)、原发灶临床靶体积(CTV1)剂量分布;统计各邻近器官剂量的实际剂量。结果 在线修正后及治疗结束后3个方向的摆位误差均小于摆位前,偏差≤2mm的人数比例高于摆位前(P<0.05);各靶区实际剂量均低于计划剂量,放疗中期、治疗结束后GTVnx、GTVnd、CTV1剂量分布对比无明显差异(P>0.05);脑干、脊髓及颌骨放疗中期、治疗结束后的平均剂量对比无明显差异(P>0.05),腮腺放疗中期的平均剂量高于治疗结束后(P<0.05)。结论 CBCT可有效减小摆位误差,降低邻近器官的辐射剂量,而靶区在线修正前后的剂量分布无明显差异。Objective To observe the setup errors of cone beam computed tomography(CBCT) in intensity modulated radiotherapy(IMRT) for nasopharyngeal carcinoma and its influences on target volume and adjacent organ dose. Methods A total of 120 patients with nasopharyngeal carcinoma who underwent IMRT in the hospital from June 2017 to June 2020 were enrolled. CBCT images were obtained by CBCT system. The actual CT images were obtained before setup, after online correction and at end of treatment. The setup errors and the proportion of patients with deviation not longer than 2mm before setup, after online correction and at end of treatment, actual dose and planned dose of each target volume, as well as dose distribution of gross tumor volume of primary tumor(GTVnx), the gross tumor volume of metastatic lymph nodes(GTVnd) and the clinical target volume 1(CTV1) before radiotherapy and during intermediate stage of radiotherapy were compared. The actual dose of each adjacent organ dose was statistically analyzed. Results After online correction and after treatment,the setup errors in the three directions were smaller than those before setup, while the proportion of patients with deviation not longer than 2mm was more than that before setup(P<0.05). The actual dose was fewer than planned dose in each target volume. There was no significant difference in the dose distribution of GTVnx, GTVnd and CTV1 during intermediate stage of radiotherapy and after treatment(P>0.05). There was no significant difference in the average dose of brainstem, spinal cord and jaw during intermediate stage of radiotherapy and after treatment(P>0.05). The average dose of parotid during intermediate stage of radiotherapy was more than that after treatment(P<0.05).Conclusion CBCT can effectively reduce the setup error and reduce the radiation dose of adjacent organs. There is no significant difference in the dose distribution before and after the online correction of target volume.

关 键 词：锥形束CT 鼻咽癌 调强放疗 摆位误差 放射剂量 

分 类 号：R445.3[医药卫生—影像医学与核医学] R739.6[医药卫生—诊断学]