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Radiobiological Demonstration of Dosimetric Predictors for Radiation Pneumonitis in Stereotactic Body Radiotherapy for Non-Small Cell Lung Cancer

JY Lu, BT Huang*, Cancer Hospital of Shantou University Medical College


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: Although stereotactic body radiation therapy (SBRT) for non-small cell lung cancer (NSCLC) has achieved encouraging outcomes by now, the dosimetric predictors for radiation pneumonitis (RP) is controversial. The study aims to identify the signi�cant dose-volume predictors associated with RP after SBRT for peripheral lung cancer using radiobiological analysis.

Methods: We analyzed 32 patients who underwent SBRT for peripheral lung cancer. The dose was prescribed with two frequently used dose regimes of 48 Gy in 4 fractions and 45 Gy in 3 fractions. The normal lung was defined as bilateral lung excluding gross target volume (GTV). The clinical parameters, including GTV, planning target volume (PTV), normal lung volume, PTV in the lung tissue (PTV_Lung), PTV to normal lung volume ratio (PTV/Lung) and PTV_Lung to normal lung volume ratio (PTV_Lung/Lung) were collected. The dose-volume parameters, including V5, V10, V20, V25, V30 and mean lung dose (MLD) of the normal lung were also recorded. The incidence of grade ≥ 2 RP was predicted using two radiobiological models. The association between the incidence of grade ≥ 2 RP and the clinical and dose-volume parameters were analyzed using Spearman's rank correlation coefficients.

Results: The same results were obtained in two dose regimes and two predicting models. Among the 12 clinical and dose-volume parameters, PTV_Lung/Lung, V10-30 and MLD were highly correlated with the incidence of grade ≥ 2 RP, with a correlation coef�cient higher than 0.90. Moreover, we found V20 and V25 were the most significant predictors, with a correlation coef�cient higher than 0.98. Our result was highly in accordance with the published literatures.

Conclusion: Radiobiological models are capable of screening the dose-volume predictors for grade ≥ 2 RP after SBRT and we demonstrate that V20 and V25 are the most correlative predictors.

Funding Support, Disclosures, and Conflict of Interest: This work was sponsored by National Natural Science Foundation of China (81602667), Medical Scientific Research Foundation of Guangdong Province (A2015534, B2016048) and the Creative and Facilitating Program of Shantou University


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