Author of

• 12418

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  P3.05 - Poster Session 3 - Preclinical Models of Therapeutics/Imaging (ID 159)

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

  • 12435

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    P3.05-018 - Does elongation of treatment time in respiratory gated radiotherapy alter cell survivals? (ID 3023)

    09:30 - 09:30  |  Author(s): S. Song
    • Abstract

    Background
    Respiratory gated radiotherapy (RGRT) is a modern radiotherapy technique, which is increasingly used technique to take account of respiratory motion. One potential risk of RGRT is the possibility of sublethal repair during treatment leading more tumor cell survival. This study assessd the influence of elongation of treatment time in respiratory gated radiotherapy by measuring cell survival in vitro.

    Methods
    Human lung cancer cell lines, H460 and H1299, were irradiated with 6MV photons using Varian 21EX linear accelerator in two different delivery models. Cells of conventional model irradiated continuously while the other cells irradiated with gated delivery. Doses of 2 Gy, 4 Gy and 8 Gy were studied. In conventional model, treatment times were 0.5 min for 2 Gy and 3min for 8 Gy including latency for multiple field. In gated delivery model, treatment times were 2.5 min for 2 Gy and 11 min for 8 Gy with 20% gating efficacy.

    Results
    H1299 cells were radioresistant than H460 cells (P<0.001). Elongation of treatment time caused significant increase in survival fraction in H1299 cell line (p=0.046). In H460 cell line survival fractions also increased but differences were not statistically significant (p=0.107). Relative differences between two delivery models in log scale survival fraction were not increased in higher dose.

    Conclusion
    The biologic effects of protracted delivery with gated technique were different between cell lines, suggesting influence of diversity of sublethal damage repair. More radioresistant cell lines were affected by elongation of treatment time. These results suggest that potential risk of sparing tumor in prolonged delivery time with gated radiotherapy should be considered in resistant tumor at the clinic.