Dosimetric comparison between non-coplanar volumetric modulated arc therapy using flattening filter and flattening filter-free beams during stereotactic radiosurgery for brain tumors
10.3760/cma.j.issn.1004-4221.2020.01.009
- VernacularTitle: 脑肿瘤立体定向放射外科中有无均整器模式剂量学比较
- Author:
Dingjie LI
1
;
Ru LIU
1
;
Chengliang YANG
1
;
Jinhu CHEN
2
;
Tai AN
3
;
Hong GE
1
Author Information
1. Department of Radiation Oncology, Affiliated Cancer Hospital of Zhengzhou University, Zhengzhou 450008, China
2. Department of Radiation Physics, Shandong Cancer Hospital Affiliated to Shandong University, Ji′nan 250117, China
3. Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee WI 53226, USA
- Publication Type:Journal Article
- Keywords:
Brain neoplasm/stereotactic radiosurgery;
Flattening filter-free beam;
Dosimetry
- From:
Chinese Journal of Radiation Oncology
2020;29(1):39-42
- CountryChina
- Language:Chinese
-
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).
Conclusions: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.
