title: Planning study of flattening filter free beams for volumetric modulated arc therapy in squamous cell carcinoma of the scalp.
abstract: OBJECTIVE
  Flattening filter free (FFF) beams show the potential for a higher dose rate and lower peripheral dose. We investigated the planning study of FFF beams with their role for volumetric modulated arc therapy (VMAT) in squamous cell carcinoma of the scalp.
  
  
  METHODS
  One patient with squamous cell carcinoma which had involvement of entire scalp was subjected to VMAT using TrueBeam linear accelerator. As it was a rare skin malignancy, CT data of 7 patients with brain tumors were also included in this study, and their entire scalps were outlined as target volumes. Three VMAT plans were employed with RapidArc form: two half-field full-arcs VMAT using 6 MV standard beams (HFF-VMAT-FF), eight half-field quarter-arcs VMAT using 6 MV standard beams (HFQ-VMAT-FF), and HFQ-VMAT using FFF beams (HFQ-VMAT-FFF). Prescribed dose was 25 × 2 Gy (50 Gy). Plan quality and efficiency were assessed for all plans.
  
  
  RESULTS
  There were no statistically significant differences among the three VMAT plans in target volume coverage, conformity, and homogeneity. For HFQ-VMAT-FF plans, there was a significant decrease by 12.6% in the mean dose to the brain compared with HFF-VMAT-FF. By the use of FFF beams, the mean dose to brain in HFQ-VMAT-FFF plans was further decreased by 7.4% compared with HFQ-VMAT-FF. Beam delivery times were similar for each technique.
  
  
  CONCLUSIONS
  The HFQ-VMAT-FF plans showed the superiority in dose distributions compared with HFF-VMAT-FF. HFQ-VMAT-FFF plans might provide further normal tissue sparing, particularly in the brain, showing their potential for radiation therapy in squamous cell carcinoma of the scalp.
authors.affiliation: Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, PR China.
authors.forename: Youqun
authors.initials: Y
authors.lastname: Lai
authors.affiliation: Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, PR China.
authors.forename: Liwan
authors.initials: L
authors.lastname: Shi
authors.affiliation: Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, PR China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Lin
authors.affiliation: Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, PR China.
authors.forename: Lirong
authors.initials: L
authors.lastname: Fu
authors.affiliation: Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, PR China.
authors.forename: Huiming
authors.initials: H
authors.lastname: Ha
mesh_terms: D001932:Brain Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D002294:Carcinoma, Squamous Cell / Q000473:pathology* / Q000532:radiotherapy*; D006801:Humans; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated; D012535:Scalp / Q000473:pathology* / Q000528:radiation effects; D012878:Skin Neoplasms / Q000473:pathology / Q000532:radiotherapy*