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  P3.17 - Treatment of Locoregional Disease - NSCLC (Not CME Accredited Session) (ID 983)

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

  • 27798

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    P3.17-06 - Impact of Integrating PET-CT in Radiotherapy Planning of Non Small Cell Carcinoma Lung: Dosimetric and Radiobiological Comparison (ID 12262)

    12:00 - 13:30  |  Presenting Author(s): Rakesh Kapoor
    • Abstract
    • Slides

    Background
    

    For conformal radiotherapy planning of NSCLC ,CT scan has been the commonly used imaging modality.The integration of PET and CT scans allows the simultaneous use of biologic and anatomic imaging data for better delineating tumor and sparing normal critical structures. The impact of this integration of two modalities in conformal radiotherapy planning has been studied in this article.The aim is to assess the impact on target volume delineation using CTvs PETCT based plans, and to determine the radiobiological effect on tumor & normal tissue by comparing Tumor control probability & normal tissue complication probability of CT & PET-CT based plans.

    a9ded1e5ce5d75814730bb4caaf49419 Method
    

    15 patients of inoperable NSCLC planned for radical radiotherapy, underwent a planning CT scan of the thorax. Target volumes were contoured ICRU 50 recommendations. Later a planning PET-CT scan was taken and the PETCT images with the auto contoured MTV (Metabolic target volume) images, were then fused with the planning CT images using rigid bony registration. Margins were given to PETMTV for the generation of PET CTV and PET PTV. Organ at risk were contoured. 3 Dimensional conformal radiotherapy (3DCRT) plans were initially made on the planning CT images keeping in mind the tolerance of various organs, mainly the normal lungs and spinal cord. Following which similar treatment plans were made on the planning PETCT images. These PETCT plans were then compared with the 3D-CRT plans generated using CT images both dosimetrically from data obtained from Dose volume histograms (DVH) and radiobiologically from mathematical models like TCP and NTCP.

    4c3880bb027f159e801041b1021e88e8 Result
    

    PET-CT resulted in a statistical significant (p = 0.01) decrease in PETCT generated MTV (103cc) versus GTV delineated on CT (157cc,statistically significant (p=0.05) higher lymph nodal volume detection (26cc) than that detected using CT scan (15cc). The PETCT CTV (334cc) and PTV (800cc) were significantly less than the CT CTV (432cc) and PTV (949cc). PETCT resulted in a statistical significant decrease in the volume of the normal lung irradiated in terms of V40 (p=0.027) and the MLD (p=0.017) but the decrease in other parameters like the V5, V10, V20 did not reach statistical significance. TCP for PETCT based plans was slightly higher than that with CT based plans, PETCT planning showed statistically significant decrease in the NTCP for lung and spinal cord.

    8eea62084ca7e541d918e823422bd82e Conclusion
    

    Incorporation of PETCT into radiotherapy planning of NSCLC is technically feasible and dosimetrically appealing but requires matched clinical correlation in terms of local tumor control and normal tissue complications.

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