Author of

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  P3.16 - Treatment of Early Stage/Localized Disease (Not CME Accredited Session) (ID 982)

  • Event: WCLC 2018
  • Type: Poster Viewing in the Exhibit Hall
  • Track:
  • Presentations: 1
  • Moderators:
  • Coordinates: 9/26/2018, 12:00 - 13:30, Exhibit Hall

  • 27755

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    P3.16-15 - Kinetic Energy Distribution for Gated Technique at Lung Ablative Body Radiotherapy (SABR) (ID 14375)

    12:00 - 13:30  |  Presenting Author(s): Kaile Li
    • Abstract
    • Slides

    Background
    

    Gated technique could be applied for lowering the dose spillage of motion target stereotactic body radiotherapy. There are three clinical steps in gated therapy. The first is the target delineation with 4DCT, the second is the localization for region of interested based on selected gated window and CBCT images, and the third is the gated delivery. At current clinical scale, radiation and target formed six combinations, which were determined by motion and static state of both radiation and target at the condition of with and without gated approach. In this study, the kinetic energy distribution for phased targets were evaluated based on gated radiotherapy procedure.

    a9ded1e5ce5d75814730bb4caaf49419 Method
    

    A Patient with tumor adjoined to the heart was selected to simulate a gated lung SBRT case with 9 co-plane beams. The prescription was 50Gy in 5 fractions. The internal target volume (ITV) based on window size was selected to be 20% to 60% of breathing cycle phase. And this fixed radiation beam aperture was determined by the sum of target from phases at 20%, 30%, 40%, 50% and 60%. The dosimetric characteristics of these individual targets, their sum, and overlap region were described with coverage level, conformity index, homogeneity index, and kinetic energy distribution was defined to be the product of mean dose and prescribed target volumes (PTVs) at different phase window sizes. The ranges of these energy distributions were compared with static target with static radiation beam.

    4c3880bb027f159e801041b1021e88e8 Result
    

    For image sets at phase 20%, 30%, 40%, 50%, 60%, sum of these phase and overlap region, the ITVs were 12.8cc, 14.2cc, 14.4cc, 16.2cc, 13.7cc, 25cc and 6.5cc; their corresponding prescription dose coverage were 96.6%, 98.2%, 96.1%, 96.3%, 97.9%, 95% and 99.3%; their corresponding conformity indexes were 1.88, 1.55, 1.67, 1.56, 1.73, 1.11, and 2.94; their homogeneity indices were equal to 1.64; and the integral energy were 4.69KGycc, 5.69KGycc, 5.31KGycc, 5.59KGycc, 4.97KGycc, 7.77KGycc and 3.04KGycc.

    8eea62084ca7e541d918e823422bd82e Conclusion
    

    In this static beam with motion target simulation, the overlap region received about 1.9 times of kinetic energy density to that of single phase target. The spillage level to adjoined critical structure could be lower with smaller gated window. The relationship between kinetic energy distribution and clinical dosimetry sufficiency could be further investigated in different physical scale levels.

    6f8b794f3246b0c1e1780bb4d4d5dc53

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