Ph.D. Proposal Presentation by Xin Zhang
Thursday, April 28, 2005

(Dr. Chris Wang, Chair)

"A New Biophysical Model for Radiation-Induced Cell Death"


The proposed study is to develop and validate a new biophysical model that is capable of predicting the survival fractions of cells irradiated with mixed high- and low-LET radiations and with various dose rates. The new biophysical model is based on both the physical quantities of energy deposition at the subcellular levels and the biological quantities associated with the cell's repair rate to radiation damages.

The validation of the model will include validating the new model by using the already published cell survival data and by conducting additional cell survival experiments with 60 Co gamma rays and reactor fission neutrons. Three sets of experiments will be conducted. First, V79 Chinese hamster cells will be irradiated with 60 Co gamma rays of various absorbed doses and dose rates to obtain low-LET survival curves. Second, V79 cells will be irradiated with fission neutrons of various absorbed doses to obtain high-LET survival curves. Third, V79 cells will be irradiated with both fission neutrons and gamma rays either concurrently or sequently to obtain the mixed-LET survival curves. The cell survival curves thus obtained will be used to either validate or adjust the quantities adopted in the new biophysical model.

The completion of this project will not only further the knowledge of the mechanisms of radiation-induced cell death but it will also provide the theoretical ground for dosimetry protocols for new cancer treatment modalities that use mixed-LET radiation fields.