title: Re-irradiation of rat tails to necrosis at six months after treatment with a "tolerance" dose of x rays or neutrons.
abstract: Rat tails were re-irradiated to necrosis levels at about six months after various fractionated treatments with 290 kV X rays or 14 MeV neutrons. The X ray dose required to produce necrosis in half of a group of tails (ND50), which had been heavily X-irradiated six months before, was 91+/-4% of the ND50 for aged controls. After prior neutron-irradiation, however, this value was 87+/-4% (neutrons in second treatment) or 75+/-5% (X rays in second course). The "effective" oxygenation of mouse tails at this time after X-irradiation was similar to that of controls; thus these percentage dose values indicate the remarkable tolerance of this organized tissue to a second course of X-irradiation, and the presence of more residual injury in neutron-irradiated tissues.
mesh_terms: D000818:Animals; D005260:Female; D051379:Mice; D009336:Necrosis; D009502:Neutrons; D011829:Radiation Dosage; D011833:Radiation Injuries, Experimental; D011836:Radiation Tolerance; D051381:Rats; D013623:Tail / Q000473:pathology / Q000528:radiation effects*; D013997:Time Factors; D014965:X-Rays