The Office of Health and Environmental Research (OHER) has supported and
continues to support development of computational approaches in biology
and medicine. OHER's Radiological and Chemical Physics Program initiated
development of computational approaches to determine the effects
produced by radiation of different quality (such as high energy
electrons, protons, helium and other heavy ions, etc. ) in a variety of
materials of biological interest-such as water, polymers and DNA; these
include molecular excitations and sub-excitations and the production of
ionization and their spatial and temporal distribution. In the past
several years, significant advances have been made in computational
methods for this purpose. In particular, codes based on Monte Carlo
techniques have -been developed that provide a realistic description of
track-structure produced by charged particles. In addition, the codes
have become sufficiently sophisticated so that it is now possible to
calculate the spatial and temporal distribution of energy deposition
patterns in small volumes of subnanometer and nanometer dimensions.
These dimensions or resolution levels are relevant for our understanding
of mechanisms at the molecular level by which radiations affect
biological systems. Since the Monte Carlo track structure codes for use
in radiation chemistry and radiation biology are still in the
developmental stage, a number of investigators have been exploring
different strategies for improving these codes.
