Giri P G, Kimler B F, Giri U P, Cox G G, Reddy E K
Int J Radiat Oncol Biol Phys. 1985 Mar;11(3):527-34. doi: 10.1016/0360-3016(85)90184-1.
The effect of fractionated thoracic irradiation on the development of normal tissue damage in rats was compared to that produced by single doses. Animals received a single dose of 15 Gy, 30 Gy in 10 daily fractions of 3 Gy each (fractionation), or 30 Gy in 30 fractions of 1 Gy each 3 times a day (hyperfractionation). The treatments produced minimal lethality since a total of only 6 animals died between days 273 and 475 after the initiation of treatment, with no difference in survival observed between the control and any of the 3 treated groups. Despite the lack of lethality, evidence of lung damage was obtained by histological examination. At times less than 180 days after treatment, the lungs of animals receiving a single dose of 15 Gy displayed more severe changes than did animals from either fractionation group. At longer times after treatment (days 261 and 475), the histological appearances within each group were changed, collagen deposits and fibrosis being the most significant observations. Animals that had received either single doses or fractionated doses had more of the pulmonary parenchyma involved than did animals that had received hyperfractionated doses. We conclude that, in the rat lung model, a total radiation dose of 30 Gy fractionated over 14 days produces no more acute lethality nor damage to lung tissue than does 15 Gy delivered as a single dose. However, long-term effects as evidenced by deposits of collagen and development of fibrosis are significantly reduced by hyperfractionation when compared to single doses and daily fractionation.
将分次胸部照射对大鼠正常组织损伤发展的影响与单次照射所产生的影响进行了比较。动物接受单次15 Gy剂量、30 Gy分10次每日给予每次3 Gy（分次照射），或30 Gy分30次每次1 Gy一天3次给予（超分割照射）。这些治疗产生的致死率极低，因为在治疗开始后的273天至475天之间总共只有6只动物死亡，对照组与3个治疗组中的任何一组之间在生存率上均未观察到差异。尽管没有致死情况，但通过组织学检查获得了肺部损伤的证据。在治疗后不到180天的时候，接受单次15 Gy剂量的动物肺部显示出比任何一个分次照射组的动物更严重的变化。在治疗后更长时间（261天和475天），每组的组织学表现都发生了变化，胶原沉积和纤维化是最显著的观察结果。接受单次剂量或分次剂量的动物比接受超分割剂量的动物有更多的肺实质受累。我们得出结论，在大鼠肺部模型中，在14天内分次给予30 Gy的总辐射剂量与单次给予15 Gy相比，不会产生更多的急性致死率，也不会对肺组织造成更多损伤。然而，与单次剂量和每日分次照射相比，超分割照射可显著降低由胶原沉积和纤维化发展所证明的长期影响。
