应用扇形束兆伏级CT研究鼻咽癌断层调强放射治疗的摆位误差  

Analysis of inter-fraction setup error of nasopharyngeal carcinoma treated with tomotherapy with mugavoltage computed tomography

作　　者：王方正[1] 蒋春儿[2] 叶智敏[1] 胡福军[1] 王磊[1] 杨双燕[3] 郁欢欢 徐敏[3] 时建芳 傅真富[1] Wang Fangzheng Jiang Chuner Ye Zhimin Hu Fujun Wang Lei Yang Shuangyan Yu Huanhuan Xu Min Shi Jianfang Fu Zhenfu(Department of Radiation Oncology of Zhejiang Cancer Hospital, Zhejiang Key Laboratory of Radiation Oncology, Hangzhou 310022, China Department of Breast Surgery, Zhefiang Cancer Hospital, Hangzhou 310022, China Department of Physics, Zhejiang Cancer Hospital, Hangzhou 310022, China)

机构地区：[1]浙江省肿瘤医院放疗科,浙江省放射肿瘤重点实验室,杭州310022 [2]浙江省肿瘤医院乳腺外科,杭州310022 [3]浙江省肿瘤医院物理室,杭州310022

出　　处：《中国医师杂志》2017年第6期883-888,共6页Journal of Chinese Physician

摘　　要：目的应用扇形束兆伏级电子计算机断层扫描（MVCT）研究鼻咽癌断层调强放射治疗分次间的摆位误差，探讨影响摆位误差的因素，为制定临床靶区外的计划靶区边界提供依据。方法将2015年2月至2015年9月37例在本院接受断层调强放射治疗的鼻咽癌患者纳入研究。所有患者分别于每日常规摆位后、断层调强放射治疗前行MVCT，并与计划CT匹配，纠正摆位，获取每次摆位误差。通过MPTV：2．5∑＋0．76[MPTV：计划靶区（肼V）外放边界；∑：系统误差；6：随机误差]计算MPTV。结果37例鼻咽癌患者在三维方向的体位校正前各方向和旋转角度的误差绝对值均值分别为左右方向（2．102±0．0406）mm；头尾方向（1．490±0．0348）mm；前后方向（1．306±0．335）mm和旋转（1．392±0．0384）°，分次间三维方向位移随时间逐渐增加且有统计学意义（P〈0．05）。摆位误差调整前各方向MPTV为左右方向3．4675mm，头尾方向2．9795mm，前后方向2．8885mm，单因素分析显示影响摆位误差的因素有体重下降、肿瘤退缩。结论鼻咽癌断层调强放疗计划设计时应采用断层照射技术相关的MPTV，摆位误差随治疗时间逐渐增大，纠正摆位误差保证了断层调强放疗的精确实施。Objective To evaluate the inter-fraction setup error during the treatment with megavoltage computed tomography （MVCT） and provide theoretical basis for clinical target volume-planning target volume （CTV-PTV） margins for nasopharyngeal carcinoma （NPC） patients treated with tomotherapy. Methods Thirty-seven consecutive NPC patients treated with tomotherapy were prospectively enrolled for the study between February 2015 and September 2015. For each patient, one MVCT scan was obtained after conventional positioning, online correction and tomotherapy delivery daily, and the scan was registered to the planning CT to determine inter-fraction setup error. The expanding margin for PTV （MPTV） was calculated with the recipe： MPTV = 2 . 5° ＋ 0 . 76 （∑ ： systematic error; 6： random error）. Results The average absolute errors of the inter-fraction were （2. 102±0. 040 6）mm, （ 1. 490±0. 034 8 ） mm, （ 1. 306±0. 335） mm and （ 1. 392±0. 038 4）° in the three dimensions. Gradual increases in both inter-fraction three-dimensional displacement were observed with time and treatment （P 〈 0. 05 ）. The total MPTV accounting for inter-error were 3. 467 5 mm,2. 979 5 mm and 2. 888 5 mm. Conclusions Tomotherapy irradiation technology personalized MPTV should be adopted for the design of tomotherapy plan. Displacement increased as a function of time.

关 键 词：体层摄影术 x线计算机 鼻咽肿瘤/放射摄影术 放射疗法 调强适形 

分 类 号：R730.55[医药卫生—肿瘤] R739.63[医药卫生—临床医学]