Author of

• 35916

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  P53 - Tumor Biology and Systems Biology - Basic and Translational Science - Misc. Topics (ID 213)

  • Event: WCLC 2020
  • Type: Posters
  • Track: Tumor Biology and Systems Biology - Basic and Translational Science
  • Presentations: 1
  • Moderators:
  • Coordinates: 1/28/2021, 00:00 - 00:00, ePoster Hall

  • 35922

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    P53.05 - Evaluation of IGRT-Induced Imaging Doses and Secondary Cancer risk for SBRT Early Lung Cancer Patients in Silico Study (ID 2937)

    00:00 - 00:00  |  Presenting Author(s): YanHua Duan
    • Abstract
    • Slides

    Introduction
    

    The imaging dose produced by Image guided radiotherapy (IGRT) will increase the secondary cancer risk.This study performed dosimetry studies and secondary cancer risk assessments on using electronic portal imaging device (EPID) and cone beam computed tomography (CBCT) as image guided tools for the early lung cancer patients treated with SBRT.

    Methods
    

    This study retrospectively analyzed the treatment plans of sixty-one early lung cancer patients treated with SBRT. The imaging doses from MV-EPID and kV-CBCT of the Edge accelerator were added to treatment plans. The MV-EPID imaging dose (6MV Photon beam) was calculated in Pinnacle TPS, and the kV-CBCT imaging dose was simulated and calculated by modeling of the kV energy beam in TPS using Pinnacle automatic modeling program. Three types of plans, namely Plan_EPID, Plan_CBCT and Plan_origin, were generated with incorporating doses of EPID, CBCT and no imaging, respectively, for analysis. The effects of imaging doses on dose-volume-histogram (DVH) criteria and plan quality were analyzed, and the excess absolute risk (EAR) of secondary cancer for ipsilateral lung was evaluated.

    Results
    

    The regions that received less than 50cGy were significantly impacted by the imaging doses, while the isodose lines greater than 1000cGy were barely changed. The DVH values of ipsilateral lung increased the most in Plan_EPID, followed by Plan_CBCT. Compared to Plan_origin on the average, the estimated EAR of ipsilateral lung in Plan_EPID increased by 3.43%, while the corresponding EAR increase in Plan_CBCT was much smaller (about 0.4%). Considering only the contribution of the imaging dose, the EAR values for the ipsilateral lung due to the MV-EPID dose in 5 years,10 years and 15 years were 1.49 cases, 2.09 cases and 2.88 cases per 10⁴PY respectively, and those due to the kV-CBCT dose were about 9 times lower, correspondingly.

    Conclusion
    

    The imaging doses produced by MV-EPID and kV-CBCT had little effects on the target dose coverage. The secondary cancer risk caused by MV-EPID dose is more than 8.5 times that of kV-CBCT.

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