The Interface Physique Biologie group at CENBG
Laboratory website: http://www.cenbg.in2p3.fr/
Light-ion microbeams provide a unique opportunity to irradiate biological samples at the cellular level and to investigate radiobiological effects at low doses of high Linear Energy Transfer ionizing radiation. A single-ion irradiation facility has been developed since 1998 on the focused horizontal microbeam line of the CENBG 3.5 MV Van de Graaff accelerator (http://www.cenbg.in2p3.fr/). This setup delivers single protons and alpha particles of a few MeV in air onto cultured cells. The spatial resolution of the beam of a few microns allows subcellular targeting.
Our group is using the GEANT4 simulation toolkit - http://geant4.web.cern.ch/geant4/ - developed for High Energy Physics, to reproduce the CENBG microbeam line from the entrance in the microprobe up to the cellular matter. The GEANT4 simulation allows to follow the different processes of ion diffusion along the beam line elements (collimators, focusing magnetic quadrupoles, beam pipe residual gas, single ion transmission detector, exit window, irradiation dwell, …) which can increase the spatial and energy dispersion of the beam and degrade the targeting resolution. The deposited energy by the incident ions and the corresponding dose within the cell nucleus and cytoplasm can be estimated as far as the cell average geometry and chemical composition are sufficiently well described.
The next-generation ultrastable accelerator in place at CENBG in 2006 – the AIFIRA project http://www.cenbg.in2p3.fr/extra/aifira.html –, will be connected to a nanobeamline to achieve a submicron resolution for cellular irradiation. We believe GEANT4 and its forthcoming additional components at the cellular level – the GEANT DNA project http://www.ge.infn.it/geant4/dna/index.html – will benefit from these experimental developments to provide a reliable simulation framework and study the interactions of radiation at cellular and DNA level.
COST P9 working group(s) of interest: WG4 and WG5