Normal Tissue Tolerance of Microplanar Beam X-ray: A Long-term Observation

Abstract

and 6 Gy. Twenty-four hours after irradiation, cells were re-plated and surviving fractions measured by clonogenic assay. Results: Polyamide treatment alone did not decrease surviving fraction in the absence of irradiation. The radiosensitization by polyamide treatment increased with radiation dose. Surviving fractions at 2 Gy were 0.660.07 and 0.550.05 (SER 1.2); at 4 Gy were 0.410.02 and 0.220.02 (SER 1.9); at 6 Gy were 0.220.07 and 0.110.01 (SER 2.0) for vehicle and polyamidetreated cells, respectively. Calculated D0 values were 4.16 Gy (vehicle) and 2.79 Gy (polyamide). SER: sensitization enhancement ratio. Errors are standard deviations (n Z 3). Conclusions: The polyamide demonstrated radiosensitization of UM-SCC12 cells in vitro. These results justify continued investigations into the therapeutic combination of irradiation and minor groove binding polyamides. Author Disclosure: N. Nickols: None. F. Yang: None. J.A. Ratikan: None. B.C. Li: None. W.H. McBride: None. P.B. Dervan: None.