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脑肿瘤立体定向放射外科中有无均整器模式剂量学比较
李定杰1, 刘如1, 杨成梁1, 陈进琥2, An Tai3, 葛红1
1郑州大学附属肿瘤医院放疗科 450008 2山东省肿瘤防治研究院(山东省肿瘤医院), 山东第一医科大学(山东省医学科学院), 济南 250117 3威斯康星医学院放疗学部, 密尔沃基 WI 53226
Dosimetric comparison between non-coplanar volumetric modulated arc therapy using flattening filter and flattening filter-free beams during stereotactic radiosurgery for brain tumors
Li Dingjie1, Liu Ru1, Yang Chengliang1, Chen Jinhu2, An Tai3, Ge Hong1
1Department of Radiation Oncology, Affiliated Cancer Hospital of Zhengzhou University, Zhengzhou 450008, China 2Department of Radiation Physics, Shandong Cancer Hospital Affiliated to Shandong University, Ji′nan 250117, China 3Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee WI 53226, USA
Abstract：Objective To compare relevant dosimetric parameters of non-coplanar volumetric modulated arc therapy (VMAT) in treating brain tumors in conventional flattening filter (FF) or flattening filter-free (FFF) delivery mode, aiming to explore the appropriate evaluation method of accelerator for stereotactic radiosurgery (SRS). Methods Clinical data of 10 patients with single cranial tumor were retrospectively analyzed. All patients received non-coplanar VMAT at a prescription dose of 25 Gy in 1 fraction. Dosimetric parameters including conformity index (CI),heterogeneity index (HI),gradient index (GI50,GI25),gradient,volume of the brain tissue receiving larger than 10 Gy and 12 Gy(V10 and V12) and beam-on time were statistically compared between two treatment plans by paired sample t-test. Results When FFF-VMAT was compared with FF-VMAT in SRS for intracranial tumors, Paddick gradient index GI50 was 2.91±0.34 vs.3.07±0.35, 6.91±0.28 vs.7.35±0.27 for GI25,(0.57±0.07) cm vs.(0.61±0.08) cm for gradient, respectively (all P<0.05), whereas CI did not significantly differ (P>0.05). For the normal brain tissues, the average dose was (160.64±43.64) cGy vs.(174.27±53.98) cGy,(45.35±30.32)% vs.(48.37±30.88)% for V10 and (36.69±25.15)% vs.(39.48±25.37)% for V12,respectively (all P<0.05). Conclusion s Non-coplanar VMAT in FFF delivery mode can improve dose distribution and normal brain tissue sparing in the treatment of intracranial single tumors. Meanwhile, supplement of GI index and gradient index can implement comprehensive evaluation of the SRS planning.
Li Dingjie,Liu Ru,Yang Chengliang et al. Dosimetric comparison between non-coplanar volumetric modulated arc therapy using flattening filter and flattening filter-free beams during stereotactic radiosurgery for brain tumors[J]. Chinese Journal of Radiation Oncology, 2020, 29(1): 39-42.
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2020, Vol. 29 
