title: Modified Volumetric Modulated Arc Therapy in Left Sided Breast Cancer After Radical Mastectomy With Flattening Filter Free Versus Flattened Beams.
abstract: Conventional volumetric modulated arc therapy (C-VMAT) for breast cancer after radical mastectomy had its limitation that resulted in larger volumes of normal tissue receiving low doses. We explored whether there was a way to deal with this disadvantage and determined the potential benefit of flattening filter-free (FFF) beams.Twenty patients with breast cancer after radical mastectomy were subjected to 3D conformal radiotherapy (3DCRT) and VMAT treatment planning. For VMAT plans, 3 different designs were employed with RapidArc form: conventional-VMAT plan (C-VMAT), modified-VMAT plan (M-VMAT), and modified-VMAT plan using FFF beams (M-VMAT-F). Plan quality and efficiency were assessed for all plans.For each technique in homogeneity, there were no statistically significant differences. VMAT plans showed superiority compared with 3DCRT in conformity. C-VMAT plans were obviously not only superior to 3DCRT in the medium to high-dose regions (about 15-50 Gy) but also resulted in larger volumes in low-dose regions (about 0-10 Gy). M-VMAT plans were similar to M-VMAT-F. Both of them might significantly reduce the regions of low dose compared with C-VMAT (V5lung: ∼ 11.5%; V5heart: ∼ 23.8%, P < 0.05), even less than 3DCRT in heart irradiation (V2.5heart, 9.4%, P < 0.05). For liver, contralateral breast, and lung irradiation, M-VMAT-F plans were slightly superior to M-VMAT with a reduction of ∼0.08, 0.2, and 0.24 Gy in the respective mean doses (P < 0.05).C-VMAT plans showed superiority compared with 3DCRT, while also resulted in larger volumes of normal tissue receiving low doses. M-VMAT and M-VMAT-F plans might not only reduce the region in the medium to high doses but also have lower volumes in low-dose regions. M-VMAT-F plans were slightly superior compared with M-VMAT due to further contralateral organs sparing.
authors.affiliation: From the Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University (YL, SW, LS, LF, HH, QL), and Xiagang Community Health Service Centers, The First Affiliated Hospital of Xiamen University (YC), Xiamen, PR China.
authors.forename: Youqun
authors.initials: Y
authors.lastname: Lai
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Chen
authors.forename: Sangang
authors.initials: S
authors.lastname: Wu
authors.forename: Liwan
authors.initials: L
authors.lastname: Shi
authors.forename: Lirong
authors.initials: L
authors.lastname: Fu
authors.forename: Huiming
authors.initials: H
authors.lastname: Ha
authors.forename: Qin
authors.initials: Q
authors.lastname: Lin
mesh_terms: D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D015409:Mastectomy, Radical; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D000069584:Unilateral Breast Neoplasms / Q000532:radiotherapy* / Q000601:surgery