Lack of differential sparing of late ischaemic atrophy and early epidermal healing, after dose fractionation of mouse tails down to 2.6 Gy per fraction.

Abstract

Long-term atrophy of irradiated mouse tails began after about 5 months, and the incidence rose steadily to the end of the lifespan. The major associated histological change was atherosclerosis in the single tail artery. The incidence of the ischaemic atrophy was dependent on the size of the irradiated volume. The probability of ischaemic atrophy assessed at 3 years after irradiation was little dependent on the dose. The fractionation effect was described by alpha/beta congruent to 30 Gy, which was not lower than the range of values applicable for healing of the early epidermal reactions on the tail. Hence the general finding of a sparing of late effects in tissues using low doses per fraction was not observed in these experiments using dose fractions down to 2.6 Gy and the present endpoints.