Effects of radiation on growth of two human tumour cell lines surviving a previous high dose, low dose-rate, radionuclide exposure.

Effects of radiation on growth of two human tumour cell lines that survived a previous high dose, low dose-rate radionuclide exposure simulating intensive radionuclide therapy, were analyzed. The purpose was to investigate whether the survivors gained therapy induced changes in growth and radiation response. The U118MG, ParRes (parental resistant), and U373MG, ParSen (parental sensitive), glioma cells were used because they are known to be low dose-rate radiation resistant and sensitive, respectively.

Requirements regarding dose rate and exposure time for killing of tumour cells in beta particle radionuclide therapy.

Purpose: The purpose of this study was to identify combinations of dose rate and exposure time that have the potential to provide curative treatment with targeted radionuclide therapy applying low dose rate beta irradiation.

Methods: Five tumour cell lines, U-373MG and U-118MG gliomas, HT-29 colon carcinoma, A-431 cervical squamous carcinoma and SKBR-3 breast cancer, were used. An experimental model with 10(5) tumour cells in each sample was irradiated with low dose rate beta particles.

Early effects of low dose-rate radiation on cultured tumor cells.

Low-dose hyperradiosensitivity (HRS) has been found for several cell types after exposure to low doses, < 0.5 Gy, of high dose-rate (typically 50-150 Gy/h) low-LET radiation. HRS precedes the occurrence of a relative resistance for doses above 0.