SU-E-T-07: 4DCT Robust Optimization for Esophageal Cancer Using Intensity Modulated Proton Therapy

Authors

  • Liao L,

    1. Proton Therapy Center, UT MD Anderson Cancer Center, Houston, TX
    2. Department of Industrial Engineering, University of Houston, Houston, TX
    3. Varian Medical Systems, Houston, TX
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  • Yu J,

    1. Proton Therapy Center, UT MD Anderson Cancer Center, Houston, TX
    2. Department of Industrial Engineering, University of Houston, Houston, TX
    3. Varian Medical Systems, Houston, TX
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  • Li Y,

    1. Proton Therapy Center, UT MD Anderson Cancer Center, Houston, TX
    2. Department of Industrial Engineering, University of Houston, Houston, TX
    3. Varian Medical Systems, Houston, TX
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  • Zhu X,

    1. Proton Therapy Center, UT MD Anderson Cancer Center, Houston, TX
    2. Department of Industrial Engineering, University of Houston, Houston, TX
    3. Varian Medical Systems, Houston, TX
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  • Li H,

    1. Proton Therapy Center, UT MD Anderson Cancer Center, Houston, TX
    2. Department of Industrial Engineering, University of Houston, Houston, TX
    3. Varian Medical Systems, Houston, TX
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  • Lim G,

    1. Proton Therapy Center, UT MD Anderson Cancer Center, Houston, TX
    2. Department of Industrial Engineering, University of Houston, Houston, TX
    3. Varian Medical Systems, Houston, TX
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  • Zhang X

    1. Proton Therapy Center, UT MD Anderson Cancer Center, Houston, TX
    2. Department of Industrial Engineering, University of Houston, Houston, TX
    3. Varian Medical Systems, Houston, TX
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Abstract

Purpose:

To develop a 4DCT robust optimization method to reduce the dosimetric impact from respiratory motion in intensity modulated proton therapy (IMPT) for esophageal cancer.

Methods:

Four esophageal cancer patients were selected for this study. The different phases of CT from a set of 4DCT were incorporated into the worst-case dose distribution robust optimization algorithm. 4DCT robust treatment plans were designed and compared with the conventional non-robust plans. Result doses were calculated on the average and maximum inhale/exhale phases of 4DCT. Dose volume histogram (DVH) band graphic and ΔD95%, ΔD98%, ΔD5%, ΔD2% of CTV between different phases were used to evaluate the robustness of the plans.

Results:

Compare to the IMPT plans optimized using conventional methods, the 4DCT robust IMPT plans can achieve the same quality in nominal cases, while yield a better robustness to breathing motion. The mean ΔD95%, ΔD98%, ΔD5% and ΔD2% of CTV are 6%, 3.2%, 0.9% and 1% for the robustly optimized plans vs. 16.2%, 11.8%, 1.6% and 3.3% from the conventional non-robust plans.

Conclusion:

A 4DCT robust optimization method was proposed for esophageal cancer using IMPT. We demonstrate that the 4DCT robust optimization can mitigate the dose deviation caused by the diaphragm motion.

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