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Journal Of Modern Oncology[ISSN:1672-4992/CN:61-1415/R]

Issue:

2021 06

Page:

1005-1008

Research Field:

Publishing date:

Info

Title:

Effects of collimator angle on stereotactic body radiation therapy-volumetric modulated arc therapy in lung cancer

Author(s):

WANG Xuemin¹; MAO Huihui²; CHANG Xiaobin¹; QU Ximei¹; ZHAO Qiang¹; YANG Di¹; WU Xiangyang¹

1.Department of Radiotherapy Hospital Unit Radiation Therapy,Shaanxi Provincial Cancer Hospital,Shaanxi Xi'an 710061,China;2.Life and Environment Science College,Guilin University of Electronic Technology,Guangxi Guilin 541000,China.

Keywords:

collimator angle; volumetric modulated arc therapy (VMAT); stereotactic body radiation therapy (SBRT); dosimetry

PACS:

R730.55

DOI:

10.3969/j.issn.1672-4992.2021.06.021

Abstract:

Objective:To evaluate the effects of collimator angle on the dosimetric results of volumetric modulated arc therapy (VMAT) plan for patients with central non-small cell lung cancer(NSCLC) undergoing stereotactic body radiation therapy (SBRT) treatment.Methods:VMAT plans for 10 patients with central NSCLC were analyzed.Optimization was performed in Varian Eclipse.6 MV X-ray non-flattened (6FFF) and maximum dose rate of 1 400 MU/min were used.We used two full coplanar arcs in all plans(CCW 179° ~ 181°,CW 181° ~179°) with collimator angle set to （0°，0°）,（10°，350°）,（20°，340°）,（30°，330°）,（40°，320°）,（50°，310°）,（60°，300°）,（70°，290°）,（80°，280°） and （90°，270°） in one arc and the counterangle for the other.Other constraints remained unchanged.D95%,V90%,conformal index (CI),gradient index (GI),MU for target PTV and D1 500 cm3,D1 000 cm3 for lung,D15 cm3 for heart,D1.2 cm3,D0.35 cm3 for spinal cord were analyzed.Wilcoxon signed rank test was performed using SPSS.A P-value<0.05 was regarded as statistical significance.Results:The best value of D95% and V90% for PTV was at 60° and 50° respectively.The best value for CI,GI and lung,heart,D1.2 cm3 for spinal cord were at 0°.There was no significant differences for D0.35 cm3 of spinal cord.Besides,all OAR doses were significantly smaller than clinical constraints.D1 500 cm3 of lung at 50° (P＜0.05) and D15 cm3 of heart at 60° (P＜0.05) were higher than the best value for 4.1% and 3.4% respectively.Conclusion:Collimator angle rotation significantly affects the dosimetric results.Choosing an appropriate collimator angle could dramatically increase the dose of target while the OAR doses meet the clinical requirements.However,the plan complexity may increase slightly.Therefore,collimator angle should be taken into consideration to obtain a more optimized treatment plan in our clinics.

References:

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Memo

Memo:

陕西省卫生健康科研基金项目（编号：2018A007）

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