Dosimetric superiority of flattening filter free beams for single-fraction stereotactic radiosurgery in single brain metastasis.
For single-fraction stereotactic radiosurgery (SRS) using linac in brain metastases, more accurate treatment delivery with higher tumor absorbed doses and lower absorbed doses to normal tissues remains an enormous challenge. The purpose of this study was to investigate the dosimetric superiority in flattening filter free beams (FFF) for volumetric modulated arc therapy (VMAT) in single brain metastasis. 68 patients with single brain metastasis were included in this study. Every patient was subjected to VMAT treatment plans using 6 MV standard flattened (FF) beams (VMAT_FF) and 6 MV FFF beams (VMAT_FFF) with single fraction doses of 20 Gy. Dosimetric evaluation was performed by analysis of target coverage, dose gradients, beam-on time (BOT), gantry speed and number of monitor units (MU). There were no differences between VMAT_FF and VMAT_FFF plans in conformity and MU. VMAT_FFF plans showed obvious superiority in homogeneity, dose gradients and efficiency. For the mean BOT, VMAT_FFF plans provided a significant decrease by 42.8% compared with VMAT_FF. By the use of FFF beams, brain irradiation was minimized with about 2% reductions in low-dose regions (about 5-10 Gy). FFF beams not only resulted in more efficiency by reducing treatment time, but also provided further brain sparing compared to traditional techniques for SRS in single brain metastasis.
Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, PR China.
Youqun
Y
Lai
Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, PR China.
Shanyu
S
Chen
Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, PR China.
Changdong
C
Xu
Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, PR China.
Liwan
L
Shi
Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, PR China.
Lirong
L
Fu
Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, PR China.
Huiming
H
Ha
Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, PR China.
Qin
Q
Lin
Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, PR China.
Zhen
Z
Zhang
D001932:Brain Neoplasms / Q000532:radiotherapy* / Q000556:secondary*; D006801:Humans; D016634:Radiosurgery; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated; D014057:Tomography, X-Ray Computed
brain metastases; flattenig filter free; stereotactic radiosurgery; volumetric modulated arc therapy