Multiparameter data analysis of stereotactic body radiotherapy based on helical tomotherapy
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《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2019年第3期
- Page:
- 259-264
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Multiparameter data analysis of stereotactic body radiotherapy based on helical tomotherapy
- Author(s):
- CHENG Xiaolong; LIU Jiping; YANG Shuangyan; SHI Jianfang
- Department of Radiation Physics, Zhejiang Cancer Hospital, Hangzhou 310022, China
- Keywords:
- ; Keywords: helical tomotherapy; stereotactic body radiotherapy; dose verification; setup error
- PACS:
- R812
- DOI:
- DOI:10.3969/j.issn.1005-202X.2019.03.003
- Abstract:
- Abstract: Objective To discuss the methods for stereotactic body radiotherapy (SBRT) plan design and dose verification based on helical tomography, and to determine the margin value of target areas according to setup errors. Methods Forty-five cases of SBRT treated with helical tomography in the last 3 years were enrolled in this study. The process of radiotherapy plan design was analyzed, and the setting rules of various parameters were clarified. Then the absolute dose deviation and Gamma (3 mm/3%) passing rate was analyzed. Finally, the ITV-PTV margin values were calculated based on 285 setup errors. Results The pitch setting method was determined; the empirical formula was given; and the comparison table of fractional dose and pitch was made according to the optimal gantry period. The mean value of absolute dose deviation and Gamma passing rate of SBRT were -0.71%±1.32% and 98.1%±1.1%, respectively. The mean setup errors of X, Y, Z and Roll in thermoplastic body membrane group were (1.71±1.62) mm, (1.21±1.28) mm, (1.18±1.41) mm and 0.55°±1.02°, respectively, and the corresponding ITV-PTV margin values in X, Y and Z directions were 5.41, 3.92 and 3.94 mm, respectively. The mean setup errors of X, Y, Z and Roll in vacuum negative pressure pad group were (1.68±1.71) mm, (1.23±1.57) mm, (1.22±1.31) mm and 0.73°±1.21°, respectively, and the corresponding ITV-PTV margin values in X, Y and Z directions were 5.40, 4.13 and 3.97 mm. Conclusion The parameter setting and plan execution time are critical in SBRT plan design. The passing rate of SBRT dose verification is high, therefore, the evaluation standard could be improved appropriately, such as absolute dose < ±3% and Gamma (3mm/3%) <1 passing rate >95%. The setup error is related to the radiotherapy equipment, fixed technology, registration method, patients themselves and the operation of radiologist. It is necessary to determine the reliable margin value according to the actual condition, so as to provide technical supports in clinic.
Last Update: 2019-03-25