Biophysics of radiation action

Understanding the cellular response to ionizing radiation is not only necessary to meet the requirements of radioprotection, but also for medical application of radiation in cancer treatment. In terms of radiobiology, cancer therapy means the selective inactivation of malignant cells without affecting the normal healthy tissue. However, for several physical and biological reasons, this ideal situation is normally not attained. The elaboration of biophysical parameters that could be used to improve the selective sterilization of tumor cells has become one of the main activities of cellular radiobiology during the last two decades. Progress in this field has been facilitated by the development of tissue culture techniques allowing to grow and analyze cells in a synthetic nutrient medium. This chapter describes the physical and biological factors which determine cellular radiosensitivity and which are important to know for better understanding the cellular radiation action, in particular with reference to cancer treatment