 He then received US citizenship and served with the US Army Medical Corps, in Fort Bragg where he was a clinical radiologist and chief of medical education.After his army service he joined the faculty of Washington University, St. Louis, rising to full professor by 1961.In 1963, he moved to the University of California, San Francisco, as Professor and Chairman of the Department of Radiology, a position he held from 1963 to 1989.