My fundamental research interests focus on radiation-induced DNA double-strand breaks and their repair. I helped uncover the role of non-homologous end joining in chromosome aberration formation in the presence of multiple breaks and established gamma-H2AX as a sensitive in situ assay for DNA damage, which has enabled us to visualise DNA damage and study DNA repair at very low radiation doses, in tissue sections and through the cell cycle. My translational research focuses mainly on two aspects, i) the establishment and utilisation of biomarkers of radiation exposure and effect and ii) the development of strategies for molecular-targeted tumour radiosensitisation, based on tumour-specific deficiencies in the DNA damage response. I have contributed to the development of international guidelines for biological radiation exposure assessment strategies and to the design and coordination of several international biodosimetry ring trials involving national reference laboratories across Europe and beyond.