Masataka Oita1, Yoshihiro Uto2, Masahide Tominaga3, Motoharu Sasaki4, Yasuo Hara4, Taro Kishi4, Hitoshi Hori2. 1. Department of Radiological Technology, Graduate School of Health Sciences, Okayama University, Okayama, Japan Department of Life System, Institute of Technology and Science, Graduate School, The University of Tokushima, Tokushima, Japan oita-m@cc.okayama-u.ac.jp. 2. Department of Life System, Institute of Technology and Science, Graduate School, The University of Tokushima, Tokushima, Japan. 3. Department of Radiological Technology, Institute of Health Biosciences, Graduate School, The University of Tokushima, Tokushima, Japan. 4. Department of Radiology, Tokushima University Hospital, Tokushima, Japan.
Abstract
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. Copyright
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. Copyright