Independent effect of a mixed-beam regimen of fast neutrons and gamma rays on a murine fibrosarcoma
Biological effectiveness of a mixed-beam regimen of fast neutrons and photons was studied in an animal tumor system. NFSa, a spontaneous fibrosarcoma in a C3H mouse, was transplanted in the right hind legs of syngeneic male mice and locally irradiated with a single dose or five daily doses. Tumor control experiments showed that five ..gamma..-ray doses increased TCD/sub 50/ values by 20 Gy and produced a shallower slope on the dose-response curve compared to that after a single fraction. Fractionated neutron doses also increased the TCD/sub 50/ value by 9 Gy without changing the slope of the dose-response curve. A mixed-beam regimen of N-..gamma..-..gamma..-..gamma..-N resulted in an independent effect on the tumor. Second, tumor cell survival was examined by the lung colony assay. Nembutal anesthesia reduced the tumor oxic cell fraction, resulting in a single component dose-response curve after a single ..gamma.. ray. Five fractionated doses of ..gamma.. rays increased both D/sub 0/ and extrapolation number while those of fast neutrons increased only extrapolation number. The D/sub 0/ and extrapolation number of the mixed-beam regimen were again identical to those values assuming that the mixed-beam effect was independent. RBEs obtained from cell survival were fairly close to those from TCD/sub 50/ assays except single-dose experiments.
- Research Organization:
- National Inst. of Radiological Sciences, Chiba, Japan
- OSTI ID:
- 7189448
- Journal Information:
- Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 98:1; 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.
ANIMALS
ANOXIA
BARYONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
COBALT 60
COBALT ISOTOPES
DISEASES
DOSE-RESPONSE RELATIONSHIPS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
FAST NEUTRONS
FERMIONS
FIBROSARCOMAS
FRACTIONATED IRRADIATION
GAMMA RADIATION
HADRONS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IONIZING RADIATIONS
IRRADIATION
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MAMMALS
MICE
MINUTES LIVING RADIOISOTOPES
NEOPLASMS
NEUTRONS
NUCLEI
NUCLEONS
ODD-ODD NUCLEI
RADIATION EFFECTS
RADIATIONS
RADIOISOTOPES
RBE
RODENTS
SARCOMAS
SURVIVAL CURVES
VERTEBRATES
YEARS LIVING RADIOISOTOPES