Author of

• 10692

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  P1.08 - Poster Session 1 - Radiotherapy (ID 195)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Radiation Oncology + Radiotherapy
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/28/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

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    P1.08-024 - Functional imaging for normal lung avoidance with proton radiotherapy (ID 2918)

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

    Background
    Preservation of lung function is critical for patients undergoing radiotherapy for thoracic malignancies, especially in patients with compromised lung function at diagnosis. Physical properties of proton radiotherapy may permit selection of beam pathways that avoid functional lung while providing adequate tumor coverage. We demonstrate the potential for proton radiotherapy avoidance of functional lung volumes defined on SPECT/CT perfusion and ventilation imaging.

    Methods
    SPECT/CT imaging was performed with [99m]Tc-MAA for lung perfusion and [99m]Tc-DTPA for lung ventilation assessment. SPECT/CT images were co-registered to treatment planning CT images and avoidance structures representing perfused or ventilated lung regions were defined using a gradient search algorithm in MIM 6.0. Photon and proton radiotherapy plans were calculated to spare lung avoidance structures in Pinnacle 9.0 and XiO 4.8, respectively, and dose-volume parameters in total lung and functional lung avoidance structures were compared.

    Results
    A representative thoracic cancer patient with compromised and spatially heterogeneous lung function is reported on (Fig. 1). Relative to the photon plan, the proton plan provided superior total lung dose sparing (V~5~=9% vs. 25%, mean dose = 1.6 Gy vs 4.5 Gy; Fig. 2) while achieving similar tumor coverage. Additionally, superior sparing of functional lung was achieved by protons in perfused regions (V~5~<1% vs. 22%, mean dose = 0.1 Gy vs 3.1 Gy) and ventilated regions (V~5~=1% vs. 33%, mean dose = 0.1 Gy vs 4.5 Gy). Figure 1 Figure 2

    Conclusion
    Functional avoidance treatment planning for thoracic patients receiving radiotherapy has been demonstrated with SPECT/CT imaging. In particular, proton radiotherapy may provide strong advantages in this paradigm. Future investigation will focus on regional dose-response modeling and radiotherapy targeting strategies for functional avoidance.