Microirradiation of cells with energetic heavy ions

The ion microprobe SNAKE (superconducting nanoscope for applied nuclear (Kern) physics experiments) at the Munich 14 MV tandem accelerator achieves beam focusing by a superconducting quadrupole doublet and can make use of a broad range of ions and ion energies, from 20 MeV protons to 200 MeV gold ions. This allows to adjust the number of DNA single strand breaks (SSBs) and double strand breaks (DSBs) per ion and per cell nucleus from about 0.1 DSBs per ion to several 100 DSBs per ion. When irradiating with single 100 MeV 160 ions, the adapted setup permits a fwhm irradiation accuracy of 0.55 mu m in x-direction and 0.4 mu m in gamma-direction, as demonstrated by retrospective track etching of polycarbonate foils. The experiments point to investigate protein dynamics after targeted irradiation. As an example for such experiments we show a kind of three dimensional representation of foci of 7-H2AX which are visible 0.5 h after the irradiation with 100 MeV 160 ions took place. It shows the gross correlation with the irradiation pattern but also distinct deviations which are attributed to protein dynamics in the cell. (c) 2005 Elsevier B.V. All rights reserved.