High Resolution Heavy Ion Track Structure Imaging

The difference in the relative biological efficincy (RBE) of ions of same linear energy transfer (LET) but different atomic number (Z) can be attributed to the difference in the radial ionisation distribution. In this contribution we present data from measurements of the spatial ionisation pattern of heavy ions of various Z but similar LET and compare the results with track structure data obtained by Monte Carlo simulations. The measurements were made with a time projection chamber with optical readout (Optical Avalanche Chamber, OPAC) which is able to quantitatively capture the spatial ionisation pattern of an ion traversing the chambe

Molecular dynamics study of accelerated ion-induced shock waves in biological media

We present a molecular dynamics study of the effects of carbon- and iron-ion induced shock waves in DNA duplexes in liquid water. We use the CHARMM force field implemented within the MBN Explorer simulation package to optimize and equilibrate DNA duplexes in liquid water boxes of different sizes and shapes. The translational and vibrational degrees of freedom of water molecules are excited according to the energy deposited by the ions and the subsequent shock waves in liquid water are simulated. The pressure waves generated are studied and compared with an analytical hydrodynamics model which serves as a benchmark for evaluating the suitability of the simulation boxes. The energy deposition in the DNA backbone bonds is also monitored as an estimation of biological damage, something which is not possible with the analytical model