Dose-rate effects in mammalian cells
Repairable and nonrepairable components of ..gamma..-ray damage leading to cell reproductive death were determined by measuring the range over which dose rate influenced the response of noncycling C3H 10T1/2 mouse cells. Cell proliferation and cell cycle redistribution were eliminated as factors influencing the dose-rate effect in the system by irradiating confluent monolayers of contact inhibited cells. The radiosensitivity of the cells did not change, and no selective loss of damaged cells occurred over the extended treatment times. A pronounced dose-rate effect was observed over the range between 55.6 and 0.29 Gy/hr, but a limit to the repair-dependent dose-rate effect was reached at 0.29 Gy/hr since no further reduction in effect per unit dose was observed when the dose rate was reduced to 0.17 or 0.06 Gy/hr. The survival curves, which were simple exponential functions of dose at dose rates of 0.29 Gy/hr and below, have a common D/sub 0/ of 7.32 Gy and represent an accurate measurement of the nonrepairable component of damage. Log-phase cultures showed remarkably different responses over the range of dose rates, due in large part to cell cycle redistribution and in some cases, cell proliferation during exposures. The results of these studies were compared with time-dose relationships used in clinical brachy-therapy. Comparison of our data with in vivo isoeffect curves of total dose vs dose per fraction for ''early'' and ''late'' tissue responses indicate that cell cycle redistribution should not be ignored as a factor influencing time-dose relationships in radiotherapy.
- Research Organization:
- Colorado State Univ., Fort Collins, CO
- OSTI ID:
- 5348782
- Journal Information:
- Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 94:1; ISSN RAREA
- Country of Publication:
- United States
- Language:
- English
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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKALI METAL ISOTOPES
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CELL CYCLE
CELL FLOW SYSTEMS
CELL KILLING
CELL PROLIFERATION
CESIUM 137
CESIUM ISOTOPES
CONNECTIVE TISSUE CELLS
DATA
DOSE RATES
ELECTROMAGNETIC RADIATION
EMBRYONIC CELLS
EXPERIMENTAL DATA
FIBROBLASTS
GAMMA RADIATION
INFORMATION
IONIZING RADIATIONS
ISOTOPES
MAMMALS
MEDICINE
MICE
NUCLEAR MEDICINE
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
RADIATION EFFECTS
RADIATIONS
RADIOINDUCTION
RADIOISOTOPES
RADIOLOGY
RADIOSENSITIVITY EFFECTS
RADIOTHERAPY
RECOVERY
REPAIR
RODENTS
SOMATIC CELLS
SURVIVAL CURVES
THERAPY
VERTEBRATES
YEARS LIVING RADIOISOTOPES