Turesson I, Notter G, Wickström I, Johansson K A, Eklund S
Radiother Oncol. 1984 Oct;2(3):235-45. doi: 10.1016/s0167-8140(84)80064-x.
A comparison of the radiation effect of altering the treatment time per session in fractionated radiotherapy was performed on human skin with 12 MeV electrons. Four fractions of 7.2 Gy were given within 22 days, once a week. The dose per fraction was administered in 4 min and 32 min, respectively. The dose rate was about 2 Gy/min and the prolonged treatment time was achieved by dividing each dose fraction into three equal subfractions with intervals of 14-15 min. Prolongation of the treatment time resulted in a significant reduction of the skin erythema (p less than 0.001), pigmentation (p less than 0.05) and the degree of telangiectasia at 5 years (p less than 0.001). The relative biological effectiveness (RBE) for the prolonged (32 min), in relation to that of the short (4 min) treatment time, RBE4 min/32 min, was 1.09-1.10 for erythema and 1.07-1.12 for telangiectasia. These findings indicate that prolongation of the treatment time per session has to be adjusted for in clinical radiation oncology.
利用12兆电子伏电子束，对分次放射治疗中改变每次治疗时间的放射效应进行了人体皮肤比较研究。在22天内每周一次给予4次7.2戈瑞的剂量。每次剂量分别在4分钟和32分钟内给予。剂量率约为2戈瑞/分钟，延长治疗时间是通过将每个剂量分割成三个相等的子部分，间隔14 - 15分钟来实现的。治疗时间的延长导致皮肤红斑（p<0.001）、色素沉着（p<0.05）以及5年后毛细血管扩张程度（p<0.001）显著降低。与短治疗时间（4分钟）相比，延长治疗时间（32分钟）的相对生物效应（RBE），红斑的RBE4分钟/32分钟为1.09 - 1.10，毛细血管扩张的RBE为1.07 - 1.12。这些发现表明，在临床放射肿瘤学中必须对每次治疗时间的延长进行调整。
