The late effects on bone marrows in mice after total body irradiation by p(35) be fast neutrons and γ rays

Purpose: To understand the late effects on bone marrow after widefield or total body irrdiation with various types of radiation. Materials and Methods: Total body irradiation with single dose of P(35) Be fast Neutrons and γ rays respectively have been used in this study. Kunming strain mice were irradiated by fast neutrons produced by bombardment of beryllium target with 35MeV protons and the dose rate was 0.12 to 0.14 Gy/min. Nine dose levels were used in fast neutrons irradiation from 0.20 to 3.50Gy. The dose rate of 68 Co γ rays was 0.60Gy/min and irradiation was in the range of 0.25 to 9.00Gy. Sixteen dose points were studied. All animals without anesthesia were irradiated whole body with single doses by fast neutrons and γ rays respectively. One group without irradiation was regarded as control group, 90 days after irradiation all animals were sacrificed. The nucleated cells of bone marrow and the peripheral blood cells including WBC and lymphocytes were counted. Results: Our study shows that the number of nucleated cells of bone marrow in both fast neutrons and y ray groups decreased with increase of the doses. There are significant differences between irradiated groups and zero line (control group) and the slopes are −1.41±0.55 (p=0.038) and −0.98±0. 24(p=0.0015) for fast neutrons and y rays respectively. There is no significant difference between the two kinds of radiation (P>0.05). The late effects on peripheral blood cells (WBC and lymphocytes) in mice after irradiation with single doses of neutrons and y rays were significantly lower than unirradiated group ( P <0.05). However, the dependence of the values of peripheral blood cells on doses is not found and there are no significant differences between neutrons and y rays groups. Conclusions: Total body irradiation with neutrons or y rays can suppress marrow in mice in the long-term, and is more obvious with increase of doses. There is no significant difference between neutrons and y rays for the late effects studied.