| Abstract: | The early effects of an irradiation on the intestinal epithelium have been evaluated, at the tissular level, by LD50 after single and multifraction irradiation, and, at the cellular level, by numeration of the regenerated intestinal crypts (Withers technique) after a single fraction irradiation. From the set of informations provided by both criteria, one derived the values of the parameters defining the survival curve of the intestinal clonogenic crypt cells after irradiation by gamma-rays (two component model): D0 = 1.5 Gy, 1D0 = 4.5 Gy, nD0 = 2.25 Gy and n = 20. In other respects, the p(65) + Be neutrons RBE (ref. 60-Cobalt) after a single fraction irradiation is equal to 1.75 +/- 0.2 and 1.64 +/- 0.25 for the LD50 at the 5th day and for the regeneration of 50 crypts after 3.5 days respectively. |
