Effects of flattening filter on dosimetry in fractionated stereotactic radiotherapy for brain metastases
10.13491/j.issn.1004-714X.2022.05.018
- VernacularTitle:均整器对颅脑分次立体定向放疗剂量学影响
- Author:
Zhijian ZHU
1
,
2
,
3
;
Xiaoye ZHANG
1
,
2
,
3
;
Yan ZHANG
1
,
2
,
3
;
Tingting SHI
1
,
2
,
3
;
Jun HONG
1
,
2
,
3
;
Dongcheng HE
1
,
2
,
3
;
Jihua HAN
1
,
2
,
3
Author Information
1. The Affiliated Huaian No.1 People'
2. s Hospital of Nanjing Medical University, Huai'
3. an 223300 China.
- Publication Type:Journal Article
- Keywords:
Brain metastasis;
Flattening filter;
Flattening filter free;
Fractionated stereotactic radiotherapy
- From:
Chinese Journal of Radiological Health
2022;31(5):615-619
- CountryChina
- Language:Chinese
-
Abstract:
Objective To investigate the dosimetric differences between volumetric modulated arc therapy (VMAT) with a flattening filter (FF) and flattening filter-free (FFF) VMAT in fractionated stereotactic radiotherapy for brain metastases. Methods Seventeen patients with brain metastases were divided into FF-VMAT group (VMAT plans with the FF mode) and FFF-VMAT group (VMAT plans with the FFF mode). The two groups were compared in terms of target volume dose parameters (D98%, D2% and Dmean), the conformal index (CI), the gradient index (GI), the gradient, normal brain tissue dose parameters (V5Gy, V10Gy, V12Gy and Dmean), monitor units, and beam-on time. Results Compared with the FF-VMAT group, the FFF-VMAT group had significantly lower GI (3.33 ± 0.37 vs 3.27 ± 0.35, P = 0.001), a significantly lower gradient [(0.85 ± 0.20) cm vs (0.84 ± 0.19) cm, P = 0.002], a significantly shorter beam-on time [(177.05 ± 62.68) s vs (142.71 ± 34.59) s, P = 0.001], and significantly higher D2% [(65.69 ± 2.15) Gy vs (66.99 ± 2.03) Gy, P = 0.001] and Dmean [(58.77 ± 1.60) Gy vs (59.95 ± 1.43) Gy, P <0.001]. There were no significant differences in the CI, the D98% of the target volume, the V5Gy, V10Gy, V12Gy and Dmean of the normal brain tissue, and monitor units between FFF-VMAT and FF-VMAT. Conclusion FFF-VMAT can better protect the normal tissue around the target volume, reduce the beam-on time, and improve treatment efficiency.
