Abstract:

 Objective  To analyze the relationship between low-dose radiation dosimetry parameters and occurrence of radiation-induced lung injury in patients with non-small cell lung cancer（NSCLC）. Methods  Medical records were retrospectively analyzed for 103 patients with NSCLC who received radiation therapy. Single-factor analysis was used to explore correlations of dosimetric parameters and occurrence of grade 2 or higher radiation-induced lung injury. Parameters that significantly predicted injury were assessed for their predictive ability by examining the area under the receiver operating characteristic curve（AUC）. Results  Of the 103 patients，27（26.2%）experienced radiation-induced lung injury of grade 2 or higher. Dosimetric parameters showed the following AUCs for predicting such injury: double lung V₅，0.714；double lung MLD，0.673；ipsilateral lung V₅，0.690；ipsilateral lung V₁₀，0.693；and healthy contralateral lung V₅，0.737. Incidence of radiation-induced lung injury was significantly higher in patients with double lung V₅ ≥52.22%，double lung MLD≥1 486.75 cGy，ipsilateral lung V₅ ≥62.03%，healthy contralateral lung V₅ ≥43.60%，or ipsilateral lung V10 ≥55.67%. Conclusion Radical radiotherapy planning should take into account the influence of low-dose radiation on risk of radiation-induced lung injury.Except common parameters，such as V₂₀，V₃₀ and MLD，V₅ should also be considered.

Key words: Lung neoplasm, Radiotherapy, Lung low-dose radioactive zone volume, Radiation-induced lung injury, Predictors