Radiosensitivity uncertainty evaluation for the in vitro biophysical modeling of EMT6 cells.

BACKGROUND/AIM The aims of this study were to evaluate the cell survival uncertainty distribution of radiation and to assess the accuracy of predictions of tumor response by using three different in vitro experimental cell cultures with radiosensitizers (including etanidazole). MATERIALS AND METHODS Using EMT6 cells and X-rays, the cell survival fraction was obtained from 15, 34, and 21 different experiments under normoxic, hypoxic, and hypoxic-plus-radiosensitizer culture, respectively. RESULTS The α coefficients were 0.257 ± 0.188, 0.078 ± 0.080, and 0.182 ± 0.116 Gy(-1), respectively. The β coefficients were 0.0159 ± 0.0208, 0.0076 ± 0.0113, and 0.0062 ± 0.0077 Gy(-2), respectively. The α coefficient and the dose that killed half of the clonogens population (D50) were significantly different between normoxic cell and hypoxic cell cultures (p<0.01), respectively. The use of radiosensitizers under hypoxic conditions improved radiosensitivity. CONCLUSION Our results suggest that parameter value distributions are required for biophysical modeling of applications for radiotherapy.