High Dose Rate Intracavitary Radiotherapy Research Articles

Hypoxic protection and rcovery in tumour cells irradiated at low dose-rates and assessed in vivo.

Abstract P-388 murine leukaemia cells have been maintained in vitro under aerobic conditions for up to 24 hours before assessment of their reproductive capacity in vivo by serial dilution-assay without significantly altering their radiosensitivity. For acute irradiation with X rays delivered in vitro, the oxygen enhancement ratio was 2·5, identical with that for the same cells irradiated and assessed in vivo. There was a slightly greater effect of dose-rate for aerobic cells irradiated at 40 rads/hour than for the same cells irradiated in their hypoxic state in situ; however, this reduced the apparent oxygen enhancement ratio for the protracted irradiation only to 2·2. Implications for the use of high dose-rate intracavitary irradiation in place of protracted irradiation from radium are discussed.