Arterial wall damage by X-rays and fast neutrons

Radiation-induced atheromatosis has been studied for 200 kVp X-rays and 15 MeV neutrons. From the results of two earlier experiments, a r.b.e. < 1 was expected for neutrons. (1) Irradiation of blood-vessels caused depolymerization of the mucopolysaccharides in the vessel wall, resulting in atheromatosis, and (2) in two other mucopolysaccharide systems a r.b.e. < 1 was observed for fast neutrons. Irradiation of the carotid arteries of a total number of 120 hypercholesterolaemic rabbits, divided over several groups, with 500 and 1000 rad of X-rays or neutrons resulted, however, in atheromatous plaques which were more pronounced for neutrons than for X-rays at the 500 rad dose-level; for a dose of 1000 rad the effect of neutrons was less extensive than the effect of X-rays. These results led to the assumption that the origin of the atheromatosis seems not only to be the mucopolysaccharide depolymerization, but that radiation induced damage at the cellular level must be taken into account. (author)