Yamakawa M, Niibe H, Honjo J, Akimoto T, Furuta M, Hasegawa M, Kawaharada U
Dept. of Radiology, Gunma Univ. School of Med.
Gan No Rinsho. 1988 Oct;34(13):1764-7.
Effects of twice daily fractionations (B.I.D.) at smaller doses per fraction than 2 Gy on mammary carcinoma of C3H/He mouse (alpha/beta ratio = 15-20 Gy) were studied. Sixty percent doses of conventional fractionations (Q.D.) were irradiated twice daily with 4 hours interval. Though B.I.D. at 120 R, 150 R were less effective than Q.D. at 200 R, 250 R, B.I.D. at 180 R were more effective than Q.D. at 300 R, equivalent to the increments of the total doses. B.I.D. at smaller doses than "flexure dose" (not equal to 0.1 x alpha/beta) seemed to be less effective for tumors. Human tumors transplanted to nude mice might be useful to study therapeutic gain ratio.
研究了每天两次分割照射（B.I.D.），每次分割剂量小于2 Gy对C3H/He小鼠乳腺癌（α/β比值 = 15 - 20 Gy）的影响。以常规分割照射（Q.D.）60%的剂量，每天两次间隔4小时进行照射。虽然120 R、150 R的B.I.D.照射效果不如200 R、250 R的Q.D.照射，但180 R的B.I.D.照射效果比300 R的Q.D.照射更有效，相当于总剂量的增加。小于“转折剂量”（不等于0.1×α/β）的较小剂量B.I.D.照射对肿瘤的效果似乎较差。移植到裸鼠身上的人类肿瘤可能有助于研究治疗增益比。
