Rojas A, Joiner M C
Gray Laboratory, Mount Vernon Hospital, Northwood, Middlesex, U.K.
Radiother Oncol. 1989 Apr;14(4):329-36. doi: 10.1016/0167-8140(89)90145-x.
The use of multiple fractions per day (MFD) in radiotherapy requires information about the rate of repair of radiation injury. It is important to know the minimum interval between fractions necessary for maximum sparing of normal tissue damage, whether rate of repair is dependent on the size of dose per fraction and if it is different in early and late responding tissues and in tumours. To address these questions, the rate of repair between radiation dose fractions was measured in mouse skin (acute damage), mouse kidney (late damage) and a mouse tumour (carcinoma NT). Skin and kidney measurements were made using multiple split doses of X-rays, followed by a neutron top-up. For skin, faster recovery was obtained with 4.4 Gy fractions (t1/2 = 1.29 +/- 0.35 h, 95% CL) than with 10.5 Gy fractions (t1/2 = 3.46 +/- 0.88 h). In contrast, kidney showed slower recovery at a low dose per fraction of 2 Gy (t1/2 = 1.69 +/- 0.39 h) than at a higher dose of 7 Gy per fraction (t1/2 = 0.92 +/- 0.1 h). These data show that repair rate is dependent on the size of dose per fraction, but not in a simple way. T1/2 values now available for many different tissues generally lie in the range of 1-2 h, and are not correlated with proliferation status or early versus late response to treatment. At the doses used currently in clinical MFD treatments, these data indicate that damage in almost all normal tissues would increase if interfraction intervals less than 6 h were used.(ABSTRACT TRUNCATED AT 250 WORDS)
放射治疗中每天使用多个分割剂量（MFD）需要了解辐射损伤的修复速率。了解正常组织损伤最大程度 sparing 所需的分割之间的最小间隔很重要，修复速率是否取决于每分割剂量的大小，以及在早期和晚期反应组织及肿瘤中是否不同。为解决这些问题，在小鼠皮肤（急性损伤）、小鼠肾脏（晚期损伤）和小鼠肿瘤（NT 癌）中测量了辐射剂量分割之间的修复速率。皮肤和肾脏测量使用多次分割的 X 射线剂量，随后进行中子补充。对于皮肤，4.4 Gy 分割（t1/2 = 1.29 ± 0.35 h，95%置信区间）比 10.5 Gy 分割（t1/2 = 3.46 ± 0.88 h）恢复更快。相比之下，肾脏在每分割低剂量 2 Gy（t1/2 = 1.69 ± 0.39 h）时比每分割高剂量 7 Gy（t1/2 = 0.92 ± 0.1 h）时恢复更慢。这些数据表明修复速率取决于每分割剂量的大小，但并非简单的关系。目前许多不同组织的 T1/2 值通常在 1 - 2 小时范围内，与增殖状态或对治疗的早期与晚期反应无关。在当前临床 MFD 治疗中使用的剂量下，这些数据表明，如果分割间隔小于 6 小时，几乎所有正常组织的损伤都会增加。（摘要截断于 250 字）
