Ph.D. in Physics from the University of Heidelberg, Germany, 1990. Early development of intensity modulated radiation therapy (IMRT) at the German Cancer Research Center (DKFZ), including inverse planning algorithms and delivery of IMRT with multileaf collimators (MLC). First clinical deployment of MLC-based IMRT at the Memorial Sloan Kettering Cancer Center in New York in 1995. Since 2001 at the Massachusetts General Hospital (MGH) in Boston, development of multi-criteria optimization and robust optimization of treatment plans. Since 2008 Professor at the Harvard Medical School and Chief of the Radiation Biophysics Division at MGH. Current research interests are imaging-guided temporo-spatial optimization of treatment delivery, better ways to define the clinical target volume, and making the benefits of proton therapy available to more patients.