Radiation-Induced Hemopoietic Death in Mice as a Function of Photon Energy and Dose Rate

• Published in: Radiation research 1986-03, Vol.105 (3), p.320-327
• Main Authors: Gengozian, N., Taylor, T., Jameson, H., Lee, Elisa T., Good, R. A., Epstein, R. B.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Biological effects of radiation; Bone marrow; Bones; Cobalt Radioisotopes; Dose-Response Relationship, Radiation; Dosimetry; Female; Fundamental and applied biological sciences. Psychology; Gamma Rays; Hematopoiesis - radiation effects; Ionizing radiations; Linear accelerators; Mice; Mortality; Particle Accelerators; Photons; Radiation dosage; Radiation Injuries, Experimental - mortality; Radiotherapy; Relative Biological Effectiveness; Solar X rays; Tissues, organs and organisms biophysics
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3576688

Radiation-induced hemopoietic death was measured in mice exposed to photons of four different energies: 250-kVp X rays, 60 Co γ rays (1.25 MeV), and 6- and 25-MV photons from a linear accelerator. For each radiation source, the lethal dose which killed 50% of the population in 30 days (${\rm LD}_{50/30}$) associated with the hemopoietic syndrome was determined in groups of mice exposed to graded doses from 600 to 1150 cGy at dose rates of 20, 40, and 80 cGy/min. The calculated ${\rm LD}_{50/30}$ values for 25 and 6 MV were significantly different from each other at all exposure rates while no difference was observed between 6 MV and 60 Co. Using 60 Co γ rays as the standard, the relative biologic effectiveness was as follows: $250\ {\rm kVp}>25\ {\rm MV}>6\ {\rm MV}={}^{60}{\rm Co}$. The data suggest that there may be a greater damage to tissue within the marrow cavities following exposure to very high megavoltage radiation, a factor which must be considered with the increasing utilization of linear accelerators in the clinic and laboratory.