1. From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland (V.M., L.J., T.S., S.B., K.H., K.M., H.A., A.E.); and Institute of Radiation Physics (IRA), Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland (D.R., P.M.).