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目的：研究高剂量率（ＨＤＲ）腔内近距离辐射正常食管的组织学改变及与食管上皮细胞ＤＮＡ含量变化的关系，探讨其临床价值。方法：选用家兔４９只，分１０Ｇｙ组、１５Ｇｙ组和对照组，分别于接受照射后不同时间检查组织病理学改变及食管上皮ＤＮＡ含量变化。结果：１０Ｇｙ组仅有粘膜和粘膜下层充血和浅溃疡，７ｄ炎症明显，２周即可见上皮修复表现。１５Ｇｙ组在７～１４ｄ出现了严重的上皮及肌层损伤，持续６周以上，损伤后的修复均有明显的纤维增生。未发现受照射后食管上皮ＤＮＡ倍性（ＤＩ）的改变，Ｓ期细胞比例（ＳＰＦ）改变与组织病理学改变相一致，急性炎症期ＳＰＦ减少，恢复期ＳＰＦ回升并增高。结论：为保证正常食管免受过量照射，ＨＤＲ近距离治疗食管癌时单次剂量应在１０Ｇｙ以下。ＨＤＲ辐射对正常食管上皮的ＤＮＡ含量无明显改变，放射损伤及修复中上皮细胞周期中ＳＰＦ变化与组织病理学改变一致。
Objective: To study the relationship between the high dose rate (HDR) intraluminal normal radiation esophageal histology and the changes of DNA content in esophageal epithelial cells, and to explore its clinical value. METHODS: Fifty-nine rabbits were selected and divided into 10Gy group, 15Gy group and control group. Histopathological changes and DNA content in esophageal epithelium were examined at different times after irradiation. RESULTS: In the 10Gy group, there was only mucosal and submucosal hyperemia and superficial ulceration, and inflammation was evident at 7 days. Epithelial repair was seen at 2 weeks. In the 15Gy group, severe epithelial and muscular injury occurred in 7 to 14 days, and it persisted for more than 6 weeks. All the repairs after injury had obvious fibroplasia. No changes in DNA ploidy (DI) were observed in irradiated esophageal epithelium. Changes in S phase cell ratio (SPF) were consistent with histopathological changes. SPF decreased in acute inflammatory phase and SPF increased and increased in recovery phase. Conclusion: In order to ensure that the normal esophagus is protected from excessive exposure, the single dose of HDR in the treatment of esophageal cancer should be less than 10Gy. HDR radiation had no significant changes in the DNA content of normal esophageal epithelium, and changes in SPF during epithelial cell cycle during radiation injury and repair were consistent with histopathological changes.