Author of

• 15343

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  P3.03 - Poster Session/ Treatment of Locoregional Disease – NSCLC (ID 214)

  • Event: WCLC 2015
  • Type: Poster
  • Track: Treatment of Locoregional Disease – NSCLC
  • Presentations: 1
  • Moderators:
  • Coordinates: 9/09/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)

  • 15370

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    P3.03-027 - Lung Cancer: Doses to Mediastinal Structures Can Be Reduced with Volumetric Modulated Arc Therapy and Deep Inspiration Breath-Hold Radiotherapy (ID 2888)

    09:30 - 09:30  |  Author(s): M.C. Aznar
    • Abstract

    Background:
    When thoracic radiotherapy (RT) doses are escalated, toxicity from mediastinal structures are a limiting factor (Cannon et al. JCO 2013). In this study we examined, if deep inspiration breath-hold (DIBH) combined with volumetric modulated arc therapy (VMAT) can decrease the dose to lungs, heart, central bronchi and esophagus compared to free breathing (FB) RT.
    
    Methods:
    17 patients with stage III NSCLC were CT scanned in both FB (4DCT) and visually guided voluntary DIBH before radical RT. Lungs, heart, central bronchi, trachea, esophagus and heart subvolumes (coronary arteries and valves) were contoured. Three dimensional conformal (3DC) and VMAT plans were computed on FB and DIBH images. VMAT plans were optimized using constraints for target and lungs. DIBH plans were compared to FB plans. Friedman signed rank test with post-hoc Nemenyi test was applied.
    
    Results:
    GTV sizes were slightly smaller in DIBH (mean 119 vs. 132 ml, p=0.01). Lung volume increased in DIBH by median 60% (range 35-108%, p<0.0001) compared to FB. Median and range of dose parameters are listed in the table together with Friedman signed rank test p-values. Mean lung dose was in DIBH reduced with a median 3.2 Gy (p=0.002) with 3DC and 3.5 Gy (p<0.001) with VMAT. DIBH alone did not significantly alter heart, esophagus and trachea-bronchial dose parameters, but VMAT did. The largest differences were found between FB 3DC and DIBH VMAT. Mean doses to coronary arteries, tricuspid and pulmonary valves were significantly reduced with DIBH VMAT compared to FB 3DC (P=0.002-0.04). No differences were found for aortic and mitral valves. Figure 1
    
    
    
    Conclusion:
    DIBH VMAT decreased the estimated mean doses to heart, lungs, esophagus and bronchii compared to FB 3DC. Possibly, the dose to these structures could be further reduced, had the mediastinal structures been included in the VMAT optimization process. Combining DIBH and VMAT may facilitate dose escalation to target volumes or subvolumes, without decreasing mediastinal toxicity compared to current standard, FB RT.