Original Article
Analysis of inter-fraction setup error of nasopharyngeal carcinoma treated with tomotherapy with mugavoltage computed tomography
Wang Fangzheng, Jiang Chuner, Ye Zhimin, Hu Fujun, Wang Lei, Yang Shuangyan, Yu Huanhuan, Xu Min, Shi Jianfang, Fu Zhenfu
Published 2017-06-20
Cite as , 2017,19(06): 883-888. DOI: 10.3760/cma.j.issn.1008-1372.2017.06.023
Abstract
ObjectiveTo 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.
MethodsThirty-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 .7б (∑: systematic error; б: random error).
ResultsThe 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.
ConclusionsTomotherapy irradiation technology personalized MPTV should be adopted for the design of tomotherapy plan. Displacement increased as a function of time.
Key words:
Tomography, X-ray computed; Nasopharyngeal neoplasms/RA; Radiotherapy, intensity-modulated
Contributor Information
Wang Fangzheng
Department of Radiation Oncology of Zhejiang Cancer Hospital, Zhejiang Key Laboratory of Radiation Oncology, Hangzhou 310022, China
Jiang Chuner
Department of Breast Surgery, Zhejiang Cancer Hospital, Hangzhou 310022, China
Ye Zhimin
Department of Radiation Oncology of Zhejiang Cancer Hospital, Zhejiang Key Laboratory of Radiation Oncology, Hangzhou 310022, China
Hu Fujun
Department of Radiation Oncology of Zhejiang Cancer Hospital, Zhejiang Key Laboratory of Radiation Oncology, Hangzhou 310022, China
Wang Lei
Department of Radiation Oncology of Zhejiang Cancer Hospital, Zhejiang Key Laboratory of Radiation Oncology, Hangzhou 310022, China
Yang Shuangyan
Department of Physics, Zhejiang Cancer Hospital, Hangzhou 310022, China
Yu Huanhuan
Department of Physics, Zhejiang Cancer Hospital, Hangzhou 310022, China
Xu Min
Department of Physics, Zhejiang Cancer Hospital, Hangzhou 310022, China
Shi Jianfang
Department of Physics, Zhejiang Cancer Hospital, Hangzhou 310022, China
Fu Zhenfu
Department of Radiation Oncology of Zhejiang Cancer Hospital, Zhejiang Key Laboratory of Radiation Oncology, Hangzhou 310022, China
