Dosimetric superiority of flattening filter free beams for single-fraction stereotactic radiosurgery in single brain metastasis

Lai, Youqun; Chen, Shanyu; Che, Xu; Shi, Lei; Fu, Lirong; Ha, Huiming; Qi, Lin; Zhang, Zhen

doi:10.18632/oncotarget.13085

Cited by 16 publications

(15 citation statements)

References 25 publications

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“…This study aimed to build on the work by Lai et al 11 , Rieber et al 10 and Laoui et al 15 by evaluating 10 MV FFF alongside 6 MV FFF for single fraction intracranial SRS specifically using non-coplanar dynamic conformal arcs compared to a 6 MV flattened beam. The FFF option on modern linacs is appealing to use for high dose single fraction treatments due to the increased dose rate which can reduce treatment times.…”

Section: Discussionmentioning

confidence: 99%

“…9 Several authors have investigated the use of 6 MV FFF for SRS treatments mostly using volumetric arc therapy (VMAT) and have shown that a significant reduction in beam-ontime (BOT) and improved dose gradients are achievable with comparable conformity. [10][11][12] Abacioglu et al have compared 10 MV FFF non-coplanar VMAT for a Varian TrueBeam linac to GammaKnife treatments for 12 patients with either vestibular schwannoma or cavernous sinus meningioma. The results showed that 10 MV FFF VMAT was comparable in terms of coverage, homogeneity and organ at risk (OAR) sparing with some gains in treatment efficiency.…”

Section: Introductionmentioning

confidence: 99%

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Flattening filter free Stereotactic radiosurgery for brain metastases using dynamic conformal arcs: 6 MV or 10 MV?

et al. 2021

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Introduction: Stereotactic radiosurgery (SRS) has proven itself as an effective tool in the treatment of intracranial lesions. Image-guided high dose single fraction treatments have the potential to deliver ablative doses to tumours; however, treatment times can be long. Flattening filter free (FFF) beams are available on most modern linacs and offer a higher dose rate compared to conventional flattened beams which should reduce treatment times. This study aimed to compare 6 MV FFF and 10 MV FFF to a 6 MV flattened beam for single fraction dynamic conformal arc SRS for a Varian Truebeam linac. Materials and methods: In total, 21 individual clinical treatment plans for 21 brain metastases treated with 6 MV were retrospectively replanned using both 6 MV FFF and 10 MV FFF. Plan quality and efficiency metrics were evaluated by analysing dose coverage, dose conformity, dose gradients, dose to normal brain, beam-on-time (BOT), treatment time and monitor units. Results: FFF resulted in a significant reduction in median BOT for both 6 MV FFF (57·9%; p < 0·001) and 10 MV FFF (76·3%; p < 0·001) which led to reductions in treatment times of 16·8 and 21·5% respectively. However, 6 MV FFF showed superior normal brain dose sparing (p < 0·001) and dose gradient (p < 0·001) compared to 10 MV FFF. No differences were observed for conformity. Conclusion: 6 MV FFF offers a significant reduction in average treatment time compared to 6 MV (3·7 minutes; p = 0·002) while maintaining plan quality.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Flattening filter free Stereotactic radiosurgery for brain metastases using dynamic conformal arcs: 6 MV or 10 MV?

et al. 2021

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“…There are many treatment techniques for multiple brain metastases, each with its own characteristics . In this study, we compared six plans including CK, IMRT, VMAT, NC1, NC3 and NC5.…”

Section: Discussionmentioning

confidence: 99%

Dosimetric quality and delivery efficiency of robotic radiosurgery for brain metastases: Comparison with C‐arm linear accelerator based plans

Zhang

Yang

Wang

2019

J Applied Clin Med Phys

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The incidence of brain metastases is increasing and various treatment modalities exist for brain metastases. The aim of this study was to investigate the dosimetric quality and delivery efficiency of robotic radiosurgery (CyberKnife) for multiple brain metastases compared with C-arm linear accelerator (linac) based plans. C-arm linac based plans included intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT) and non-coplanar VMAT with 1, 3 and 5 non-coplanar arcs, respectively (NC1, NC3 and NC5). For 20 patients, six plans with a prescription dose of 30 Gy in three fractions were generated. The gradient index (GI), conformity index (CI), maximum dose (D max ) of organs at risk (OARs), normal brain tissue volume (V 3 Gy -V 24 Gy ), monitor units (MUs) and beam on time (BT) were evaluated. The GI of CyberKnife plans (3.60 ± 0.70) was lower than IMRT (6.21 ± 2.26, P < 0.05), VMAT (6.04 ± 1.93, P < 0.05), NC1 (5.16 ± 1.71, P < 0.05), NC3 (5.02 ± 1.59, P < 0.05) and NC5 (5.03 ± 1.72, P < 0.05). The CI of the VMAT plans (both coplanar and non-coplanar) was larger than IMRT and CK plans. The D max for most OARs of the CyberKnife plan was lower than the C-arm linac based plans, although some differences were not statistically significant. The normal brain tissue volume of CyberKnife plan was lower than the C-arm linac based plans, and the normal brain tissue volume of non-coplanar VMAT plans was lower than IMRT and VMAT plans at high-moderate dose level. However, the MUs and BT of CyberKnife plans was more than C-arm linac based plans. CyberKnife plan was better than C-arm linac based plans in protecting normal brain tissue and OARs for patients with multiple brain metastases. C-arm linac based plan with non-coplanar arc provided better protection of normal brain tissue than coplanar plan. However, the BT of CyberKnife plan was longer than C-arm linac based plans. K E Y W O R D SCyberKnife, dosimetry, IMRT, multiple brain metastases,

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“…Furthermore, a lower peripheral dose is a unique characteristic in FFF beams due to the decrease of photon head scatter, head leakage and leaf transmission [38]. It has been demonstrated that the dose gradients in FFF beams were superior to FF beams and that FFF provides further brain sparing compared to traditional techniques for SRS in single brain metastasis [39,40].…”

Section: Contouring and Treatment Planning Srsmentioning

confidence: 99%

LINAC based stereotactic radiosurgery for multiple brain metastases: guidance for clinical implementation

et al. 2019

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Introduction: Stereotactic radiosurgery (SRS) is a promising treatment option for patients with multiple brain metastases (BM). Recent technical advances have made LINAC based SRS a patient friendly technique, allowing for accurate patient positioning and a short treatment time. Since SRS is increasingly being used for patients with multiple BM, it remains essential that SRS be performed with the highest achievable quality in order to prevent unnecessary complications such as radionecrosis. The purpose of this article is to provide guidance for high-quality LINAC based SRS for patients with BM, with a focus on single isocenter non-coplanar volumetric modulated arc therapy (VMAT). Methods: The article is based on a consensus statement by the study coordinators and medical physicists of four trials which investigated whether patients with multiple BM are better palliated with SRS instead of whole brain radiotherapy (WBRT): A European trial (NCT02353000), two American trials and a Canadian CCTG lead intergroup trial (CE.7). This manuscript summarizes the quality assurance measures concerning imaging, planning and delivery. Results: To optimize the treatment, the interval between the planning-MRI (gadolinium contrastenhanced, maximum slice thickness of 1.5 mm) and treatment should be kept as short as possible (< two weeks). The BM are contoured based on the planning-MRI, fused with the planning-CT. GTV-PTV margins are minimized or even avoided when possible. To maximize efficiency, the preferable technique is single isocenter (non-)coplanar VMAT, which delivers high doses to the target with maximal sparing of the organs at risk. The use of flattening filter free photon beams ensures a lower peripheral dose and shortens the treatment time. To bench mark SRS treatment plan quality, it is advisable to compare treatment plans between hospitals. Conclusion: This paper provides guidance for quality assurance and optimization of treatment delivery for LINAC-based radiosurgery for patients with multiple BM.

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Dosimetric superiority of flattening filter free beams for single-fraction stereotactic radiosurgery in single brain metastasis

Cited by 16 publications

References 25 publications

Flattening filter free Stereotactic radiosurgery for brain metastases using dynamic conformal arcs: 6 MV or 10 MV?

Flattening filter free Stereotactic radiosurgery for brain metastases using dynamic conformal arcs: 6 MV or 10 MV?

Dosimetric quality and delivery efficiency of robotic radiosurgery for brain metastases: Comparison with C‐arm linear accelerator based plans

LINAC based stereotactic radiosurgery for multiple brain metastases: guidance for clinical implementation

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