Author of

• 17783

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  P2.05 - Poster Session with Presenters Present (ID 463)

  • Event: WCLC 2016
  • Type: Poster Presenters Present
  • Track: Radiotherapy
  • Presentations: 1
  • Moderators:
  • Coordinates: 12/06/2016, 14:30 - 15:45, Hall B (Poster Area)

  • 17821

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    P2.05-038 - Initial Clinical Experience of VMAT-SBRT with Flattening-Filter-Free Techniques in the University of Tokyo Hospital (ID 4524)

    14:30 - 14:30  |  Author(s): K. Nawa
    • Abstract

    Background:
    Stereotactic body therapy (SBRT) has been widely used as a safe and effective treatment method for primary or metastatic lung tumors. Among new techniques for SBRT, utilization of flattening-filter-free (FFF) beams allows more rapid delivery of treatment doses and may enable to improve clinical stability and comfort. FFF techniques have been adopted to our volumetric modulated arc therapy (VMAT)-SBRT system since 2013.We evaluated the safety and availability of VMAT-SBRT using FFF techniques in a clinical field of treatment of primary and metastatic lung tumors.
    
    Methods:
    A total of 62 lung VMAT-SBRT cases treated at our institution using an Elekta-synergy system from 11/2013 to 11/2015 were reviewed. SBRT plans using VMAT with single partial arc (220 degree) were optimized in the pinnacle[3] treatment planning system with inhomogeneity correction. We targeted at 48 cases with 1) one or two targets; 2) tumor diameter<40mm; 3) dose prescription= 55Gy/4Fr for peripheral lesions or 56Gy/7Fr for central lesions (PTV-D95); 4) image diagnostic approaches performed after treatment. In each prescription dose, We compared between two groups (flattening filter; FF vs. FFF) in total monitor units (MUs), treatment time, dose for tumors (ITV-D5, D50, D98, etc.), dose for lungs (V5,V20,MLD etc.), local recurrence, radiation pneumonitis, the other adverse events.
    
    Results:
    Before November 2014, 24 patients (peripheral: central=19:5) were treated with conventional FF VMAT, and remaining 24 patients (peripheral: central=18:6) with FFF VMAT. There were T1 primary lung tumors in 29 patients (FF:FFF= 14:15) including 8 GGOs, T2- in 10 patients (5:5), and metastatic tumors in 9 patients (5:4). In the both prescription dose, significant differences were found in the average treatment times; FF: FFF=3.65:1.45(sec) for 55Gy/4Fr, 2.28:1.26(sec) for 56Gy/7Fr respectively, while no significant difference in the mean total MUs; FF:FFF respectively, while no significant difference in the mean total MU values; FF:FFF= 2128(range, 1099-2817):2100(range, 1505-2343). The dose for tumors and lungs did not show significant differences between two groups.Local recurrence occurred in 3 patients (FF: FFF=1:2), Grade2 radiation pneumonitis occurred in 5 cases (FF: FFF=3:2), and the other adverse events were within an allowance compared with past reports.
    
    Conclusion:
    The VMAT-SBRT using FFF techniques could shorten the treatment time of lungSBRT keeping the high local control rate and the low toxicity in the clinical field.