Sensitization of low-dose-rate irradiation by nonlethal hyperthermia.
To assess whether hyperthermia could radiosensitize cells irradiated at a low dose rate, Chinese hamster V79 cells were simultaneously heated and irradiated at 0.86 Gy/h. The data showed that heat treatments at 39 and 40 degrees C, which did not induce heat killing alone or high-dose-rate radiosensitization, resulted in enhanced cell killing with low-dose-rate irradiation. The dose-modification factor (ratio of the slopes of the curves for low dose rate and high dose rate) was reduced to 1.8 at 39 degrees C and 1.4 at 40 degrees C, compared to a value of 2.1 at 37 degrees C. These data indicate that nonlethal heat treatments can cause enhanced radiosensitization under low-dose-rate conditions. The implications of these results for interstitial thermoradiotherapy are discussed.
Spiro
I J
IJ
Department of Radiation Oncology, Massachusetts General Hospital, Boston.
McPherson
S
S
Cook
J A
JA
Ling
C C
CC
DeGraff
W
W
Mitchell
J B
JB
D000818:Animals; D002470:Cell Survival / Q000528:radiation effects*; D006358:Hot Temperature; D066298:In Vitro Techniques; D011836:Radiation Tolerance / Q000502:physiology*