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M. Lizondo
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P3.14 - Radiotherapy (ID 730)
- Event: WCLC 2017
- Type: Poster Session with Presenters Present
- Track: Radiotherapy
- Presentations: 1
- Moderators:
- Coordinates: 10/18/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)
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P3.14-017 - Dosimetric Evaluation of Lung SBRT Treatment (ID 10204)
09:30 - 09:30 | Author(s): M. Lizondo
- Abstract
Background:
To analyse the relation between clinical outcomes and dosimetric indices for SBRT lung treatments.
Method:
96 lung lesions were treated with SBRT(6MV photons 3DCRT). Planning CT included whole lung. 4DCT of tumor area was used to obtain a MIP-based ITV, with three risk-adapted fractionation schemes [3x18Gy, 5x11Gy, 8x7.5Gy(BED>100Gy)]. In treatment delivery the tumor was centered online using CBCT and its movement validated by fluoroscopy adjusting the gating limits to the breathing amplitude. Toxicity and dosimetric indices for PTV and OAR were evaluated and correlated with the clinical outcomes 6 months after radiotherapy
Result:
Table1 shows the dose constraints as well as the results of the dosimetric indices. It was found that 95%/75% of the patients developed G=0 acute/late toxicity, 3%/0% G=2 acute lung/skin toxicity, 3% G=2 late lung toxicity and no patients developed G>2 toxicities. Figure 1 displays the correlation between V~100~, V~90~, CI and the clinical outcomes after 6 months of radiotherapy. Only the CI was statistically significant(t-test p=0.017) as an indicator of the ratio between complete/partial responses(mean CI=1.1/1.05) Figure 1 Figure 2
Conclusion:
The lung SBRT technique is safe(no G> 2 toxicity has been reported) even for cases with OAR compromise. The CI has been statistically significant as a predictor of complete tumor remission at 6 months.
