Powers B E, McChesney S L, Gillette E L
Department of Radiology and Radiation Biology, Colorado State University, Fort Collins 80523.
Int J Radiat Oncol Biol Phys. 1987 Nov;13(11):1673-80. doi: 10.1016/0360-3016(87)90164-7.
Seventy-two dogs were given 36 to 74 Gy to the trachea in either 2, 3, or 4 Gy per fraction. Tracheal sections were histologically and morphometrically evaluated 6 months after irradiation to determine the relative percentage of goblet cells, submucosal glands, connective tissue and blood vessels. The percent of each tissue component was plotted against total dose, regression lines calculated and isoeffective doses obtained for construction of isoeffect curves. Probit analysis for probability of surface ulceration also was done. Another group of 32 dogs received either 36, 44, or 52 Gy in 4 Gy fractions and tracheas were similarly analyzed at 1, 3, and 12 months after irradiation. Goblet cells and submucosal glands decreased with increasing total dose in each of the dose per fraction groups while connective tissue increased. Lower doses per fraction had more shallow dose response curves and higher total doses were required to produce an isoeffect. The alpha/beta ratios for tissues at 6 months after irradiation were 3.5 Gy for decrease in goblet cells, 4.7 Gy for probability for surface ulceration, 4.5 Gy for decrease in submucosal glands and 1.8 Gy for increase in connective tissue. Goblet cells and submucosal gland numbers decreased within 1 month and remained significantly decreased at higher doses at 12 months. Although there was no dose response for vasculature volume at 6 months, significant perivascular and intimal fibrosis was observed. This study revealed significant damage to the trachea at high total doses and large doses per fraction. The relatively low alpha/beta ratios obtained indicates that these adverse effects are late effects. Significant sparing of the adverse late effects was present at lower doses per fraction. These results indicate that coarser fractionation schemes that include the trachea in the treatment volume could be potentially dangerous.
72只犬接受了36至74 Gy的气管照射，每次分割剂量为2、3或4 Gy。照射6个月后，对气管切片进行组织学和形态计量学评估，以确定杯状细胞、黏膜下腺、结缔组织和血管的相对百分比。将每个组织成分的百分比与总剂量作图，计算回归线并获得等效应剂量以构建等效应曲线。还进行了表面溃疡概率的概率单位分析。另一组32只犬接受了每次分割剂量为4 Gy、总剂量为36、44或52 Gy的照射，并在照射后1、3和12个月对气管进行了类似分析。在每个分割剂量组中，杯状细胞和黏膜下腺随总剂量增加而减少，而结缔组织增加。较低的分割剂量具有更浅的剂量反应曲线，产生等效应需要更高的总剂量。照射后6个月时，组织的α/β比值分别为：杯状细胞减少为3.5 Gy，表面溃疡概率为4.7 Gy，黏膜下腺减少为4.5 Gy，结缔组织增加为1.8 Gy。杯状细胞和黏膜下腺数量在1个月内减少，在12个月时较高剂量下仍显著减少。虽然6个月时血管体积没有剂量反应，但观察到明显的血管周围和内膜纤维化。这项研究表明，高总剂量和大分割剂量对气管有显著损伤。获得的相对较低的α/β比值表明这些不良反应是晚期效应。在较低的分割剂量下，晚期不良反应有明显的 sparing 现象。这些结果表明，将气管纳入治疗体积的较粗分割方案可能具有潜在危险性。
