人恶性肿瘤细胞对 射线的分次照射效应

     【摘要】  目的  观察分次照射对三种体外培养的来源于人体不同组织的具有高辐射抗性的恶性肿瘤细胞系细胞存活分数的影响，考察它们的亚致死损伤修复的情况。方法  以三种体外培养的来源于人体不同组织的具有高辐射抗性的恶性肿瘤细胞为实验对象，单次及分次接受60Coγ射线0～6Gy内不同剂量点照射。以克隆形成率作为标准检测细胞的存活率。结果  在0～6Gy的小剂量范围内，6h分次照射的细胞存活率明显高于单次照射。结论  在6h之内，三种组织来源的肿瘤细胞都存在亚致死损伤修复。这与理论相符合，同时也与这三种肿瘤细胞在临床上对放疗的高抗性表现一致。本实验可从细胞水平上为临床治疗这三种组织来源的肿瘤细胞的放疗方案的制定提供理论依据和参考。

    【关键词】  亚致死损伤修复；肿瘤细胞；分次照射

    The effect of fractional irradiation on malignant human tumor cells irradiated with γ-rays

　　    【Abstract】  Objective  To observe the high irradiation influence of the three kinds of malignant human tumor cell lines which derived from different tissues and had low radiosensitivity. Methods  After irradiated with 60Co γ-rays， The survival fractions of single irradiation and fractional irradiation were studied by colony-formation assays. Result  That the survival fractions of fractional irradiation were higher than that of single irradiation for all of the three kinds of cells and it indicated that in 6 hours all of the three kinds of cells had high repair ability to sublethal damage. Conclusion The result was consist with the theory and the low radiosensitivity of the three kinds of cells. This assay can be considered as reference data for clinical therapy.

【Key words】  sublethal damage repair；tumor cells；fractional irradiation

    临床治疗肿瘤时，总是把剂量分成许多分次，使每个分次照射时受到的损伤有可能得到部分修复，从而对那些能积累和有效地修复损伤的细胞给予相应的保护，总治疗时间的延长让存活细胞能繁殖，并且对增殖快的组织有利。在细胞修复和再群体化之外，分次和延长时间还能有益于乏氧细胞的再氧合和导致处于细胞周期的细胞分布的改变，这些都影响照射最终的生物学效应［1］。

    分次照射的生物效应依赖于剂量分布和时间以及分次的关系。临床把照射的次数叫作分次数（fractionation)，每分次的剂量叫作分次量(frac

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