FRACTIONATED, LOW DOSE-RATE, IRRADIATION OF MICE WITH FISSION NEUTRONS AND Co$sup 60$ GAMMA-RAYS

Technical Report · Tue Jan 01 04:00:00 EST 1963

OSTI ID:4140996

Vogel, Jr, H H; Jordan, D L

Data on the comparative effects of fission neutrons and Co/sup 60/ gamma rays on lethality in CF No. 1 female mice are presented. All animals were exposed in the gammaneutron radiation chamber at the CP-5 reactor. Both radiations were delivered at a dose rate of approximately 1 rad/min. The mice exposed to gamma rays received 13 weekly doses of 300 rads, delivered in one, three, or six equal fractions per week. Under the conditions of exposure at CP- 5, fission neutrons have been found to be almost three times ss effective ss Co/ sup 60/ gamma rays for acute 30-day lethality in the mouse. An RBE value of 5 was arbitrarily chosen as a basis for the selection of the gamma dose. Thus, the total neutron weekly dose was 60 rads (total delivered in three fractionation patterns). The irradiations were continued for 13 consecutive weeks, hence the mice were exposed to almost 4000 rads of gamma rays. The mean survival tirnes of the gamma-irradiated mice are not significantly different whether they are exposed once or three times a week. There is an indication that daily exposure (six times a week) increases the mean survival time, but the numbers are small and the difference may not be significant. There is no such indication for the neutron-irradiated mice. It is clear from the data that the figure of 5 is too high for the neutron/gammaRBE under the conditions of this experiment. Data are given on the number of cases of thymic lymphomas observed at autopsy in the irradiated mice. It is evident that in the neutron-irradiated mice this reticular tumor of the thymus gland is the leading cause of death, whereas the incidence in the gamma -exposed mice is much lower. It is probable that this difference is largely and effect of the different times of mortality. (auth)

• Research Organization: Argonne National Lab., Ill.
• DOE Contract Number: W-31109-ENG-38
• NSA Number: NSA-18-003494
• OSTI ID: 4140996
• Report Number(s): TID-18386; UAC-7251
• Country of Publication: United States
• Language: English

Related Subjects

BIOLOGY AND MEDICINE
COBALT 60
DISTRIBUTION
DOSE FRACTIONATION
GAMMA RADIATION
LYMPH SYSTEM
LYMPHOMAS
MICE
NEUTRON BEAMS
RADIATION DOSES
RADIATION EFFECTS
RADIATION INJURIES
RBE
REACTORS
SEX
SURVIVAL TIME
THYMUS
TUMORS