Our research in nuclear medicine physics focuses on internal dosimetry and its coupling to biological effects, as well as the development of image processing methods for improved data analysis. We participate in a clinical research study for the treatment of neuroendocrine tumors, where our dosimetry program LundaDose plays a key role. We develop the Monte Carlo program SIMIND for optimization of imaging and dosimetry methods. New approaches are quantitative tomographic reconstruction for radionuclides with complex emission spectra, as well as methods for tumor dosimetry and validation in geometries created with 3D printers. We develop small scale models from micro anatomic organs and tissues for the investigations of radiation effects at the cell and tissue levels. DNA double strand breaks are detected by immunofluorescence microscopy and ?-H2AX biomarker. The research group has a large international network and representation in several committees and radiation protection organizations.