1. Applied Physical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, Heidelberg, Germany
2. The Jackson Laboratory, Technology Evaluation and Development, Physiology & in vivo Imaging, Bar Harbor, Maine, U.S.A.
3. German Cancer Research Center, Department of Tumor Virology, Heidelberg, Germany
4. German Cancer Research Center, Department of Medical Physics in Radiology, Heidelberg, Germany