To compare the severity of radiation-induced lung injury (RILI) after the right lung of SD rats received interstitial brachytherapy and stereotactic radiotherapy (SBRT). RILI rat model was established using interstitial brachytherapy and SBRT methods, respectively. CT scan was performed to analyze the lung volume and the CT value difference between the left and right lungs in rats. Then the lung tissues were analyzed through H&E staining, peripheral blood was extracted to detect the expression levels of serum inflammatory cytokines, pro-fibrotic cytokines, and fibrotic-inhibiting cytokines by ELISA. The difference between right and left lung CT values was significantly elevated in the SBRT group when compared with the control group and the interstitial brachytherapy group (P < 0.05). The IFN-γ expression in the interstitial brachytherapy group was significantly different from that in the SBRT group at week 1, 4, 8 and 16. Besides, the expressions of IL-2, IL-6 and IL-10 in SBRT group were significantly higher than that of interstitial brachytherapy group (P < 0.05). The TGF-β expression in interstitial brachytherapy group reached its peak with the increase of time from week 1 to week 16, and it was significantly lower than SBRT group (P < 0.05). The mortality rate in the SBRT group was 16.7%, which was significantly higher than that in the interstitial brachytherapy group. The treatment method of interstitial brachytherapy is considered as an effective and safe tool by reducing the side effects of radiotherapy and increasing the radiation dose of radiotherapy.

中文翻译：

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SD大鼠间质近距离放射治疗和立体定向放射治疗后放射性肺损伤的发生和发展

比较SD大鼠右肺接受间质近距离放射治疗和立体定向放射治疗(SBRT)后放射性肺损伤(RILI)的严重程度。分别采用间质近距离放射治疗和SBRT方法建立RILI大鼠模型。通过CT扫描分析大鼠肺体积及左右肺CT值差异。然后对肺组织进行H&E染色分析，抽取外周血，采用ELISA法检测血清炎性细胞因子、促纤维化细胞因子、纤维化抑制细胞因子的表达水平。与对照组和间质近距离放射治疗组相比，SBRT组左右肺CT值差异显着升高（P < 0.05）。间质近距离放射治疗组第1周、第4周、第8周、第16周时IFN-γ表达量与SBRT组有显着性差异;SBRT组IL-2、IL-6、IL-10表达量显着高于SBRT组。高于间质近距离放射治疗组（P < 0.05）。间质近距离放射治疗组TGF-β表达量在第1周至第16周随着时间的延长达到高峰，且显着低于SBRT组（P < 0.05）。SBRT组的死亡率为16.7%，明显高于间质近距离放射治疗组。间质近距离放射治疗的治疗方法通过减少放射治疗的副作用和增加放射治疗的辐射剂量被认为是一种有效且安全的工具。