1. U.S. Atomic Energy Commission Licensed Nuclear Reactor Operator, University of Wisconsin-Madison, 1968-1970.
2. University of Wisconsin-Madison, Postdoctoral Fellow in Physiology, 1976-1977.
3. Duke University, Associate in Radiology, 1977-1979.
4. Duke University, Assistant Professor of Radiology, 1979-1980.
5. University of Wisconsin-Madison, Visiting Assistant Professor in Human Oncology, 1981.
6. ENEA - C.R.E, Casaccia, Roma, Italia, Visiting Research Scientist at the Centro di Studi Nucleari, 1982.
7. Duke University, Assistant Professor of Radiology and Pathology, 1980-1983.
8. Duke University, Associate Professor of Radiology and Assistant Professor of Pathology, 1983-1990.
9. Duke University, Professor of Radiation Oncology and Assistant Professor of Pathology, 1990-1998.
10. Duke University, Professor of Radiation Oncology and Associate Professor of Pathology, 1998-present.
11. Duke University, Director-Division of Radiation and Molecular Oncology Research, 1991-present.
12. Duke University, Director of Basic Research, Liver Surgery Program, 1992-1996.
13. Duke University Integrated Toxicology Program, Member, 1992-present.
14. Duke University Integrated Toxicology Program, Member of the Board of Directors, 1998-present.
15. Duke University Cell and Molecular Biology Training Program, Member, 1997-present.
