1Radiological Physics, Dep. of Radiology, University of Basel Hospital, Basel, Switzerland, 2Department of Biomedical Engineering, University of Basel, Basel, Switzerland, 3Department of Diagnostic and Interventional Radiology with Nuclear Medicine, Thoraxklinik at University Hospital Heidelberg, Heidelberg, Germany, 4Department of Diagnostic and Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany