Abstract

We have an ongoing project using ultrasoft x-rays as a tool to investigate the mechanisms of radiation-induced damage in biological systems. The data which are derived from these studies are used to test the assumptions of current models of the biological and chemical mechanisms of radiation damage. In principle, refinement of these models should aid in the extrapolation of biological data obtained at high radiation doses to the low-dose region. Basic mechanistic data may also improve our understanding of the therapeutic application of radiation in the treatment of cancer. Soft x-rays are particularly attractive for these studies because they deposit their energy over nanometer-scale dimensions, comparable to the size of critical target structures within mammalian cells. For example, 0.28 keV characteristic x-rays from carbon generate photoelectrons which deposit all of their energy over a range of 7 nm, comparable to the dimensions of DNA strands (2-3 nm) and DNA-histone complexes (10 nm). Thus, these radiations serve as very precise probes of the energy deposition and lesion interaction requirements for biological damage.

© 1988 Optical Society of America