Held K Kathryn D. Held, Executive Director | Chief Science Officer

Telephone: (301) 657-2652, Ext. 20


Held K

Dr. Held was first elected to the Council in 2006 and served on the NCRP Board of Directors from 2008 to 2014. She was Vice President from 2011 to 2016 and is currently Co-Chair of Program Area Committee 1 on Basic Criteria, Epidemiology, Radiobiology, and Risk. She also served as Chair of the Program Committee for the 2011 Annual Meeting on “Scientific and Policy Challenges of Particle Radiations in Medical Therapy and Space Missions.” Dr. Held was a member of Scientific Committee (SC) 1-22 on Radiation Protection for Astronauts in Short-Term Missions and Phase I of SC 1-24 on Radiation Exposures in Space and the Potential of Central Nervous System Effects and an advisor to several NCRP committees.

Dr. Held is an Associate Radiation Biologist in the Department of Radiation Oncology, Massachusetts General Hospital (MGH) and Associate Professor of Radiation Oncology (Radiation Biology) at Harvard Medical School (HMS). At MGH, Dr. Held leads a team that is involved in research on molecular mechanisms for the induction of bystander effects by high energy particles in cells and tissues, characterization of charged particle beam induced DNA damage responses and cell killing, development of a cancer screening platform for personalized radiation medicine, and mechanisms for regulation of DNA damage response by cell-cell communication. Dr. Held also teaches radiation biology to radiation oncology medical and physics residents and graduate students at MGH/HMS and the Massachusetts Institute of Technology.

Dr. Held earned her PhD in biology from the University of Texas, Austin. She has served on review panels for numerous federal agencies including the National Institutes of Health, the National Aeronautics and Space Administration (NASA), and the U.S. Army Medical Research and Material Command programs and other organizations such as the Radiological Society of North America. She is on the Editorial Boards of Radiation Research and the International Journal of Radiation Biology, and has served on committees for the National Academy of Science/National Research Council, NASA, and the American Society of Radiation Oncology. She is a past President of the Radiation Research Society.

kathryn d. held – BIO

Advisors to the President

Preston_2014 R. Julian Preston

Telephone: (301) 657-2652



retired as the Associate Director for Health for the National Health and Environmental Effects Research Laboratory of the U.S. Environmental Protection Agency (EPA). He also served as Director of the Environmental Carcinogenesis Division at EPA and as senior science adviser at the Chemical Industry Institute of Toxicology. He has been employed at the Biology Division of the Oak Ridge National Laboratory and has served as associate director for the Oak Ridge–University of Tennessee Graduate School for Biomedical Sciences. Dr. Preston's research and current activities have focused on the mechanisms of radiation and chemical carcinogenesis and the approaches for incorporating these types of data into cancer risk assessments.

Dr. Preston was chair of Committee 1 of the International Commission on Radiological Protection (ICRP), a member of the ICRP Main Commission, and a member of the U.S. delegation to the United Nations Scientific Committee on the Effects of Atomic Radiation. He is an associate editor of Environmental and Molecular Mutagenesis, Mutation Research, Chemico-Biological Interactions, and Health Physics. Dr. Preston has had more than 200 peer-reviewed papers and chapters published. He received his BA and MA from Peterhouse, Cambridge University, England, in genetics and his PhD from Reading University, England, in radiation genetics. He has served on the National Research Council's Committee to Assess the Scientific Information for the Radiation Exposure Screening and Education Program and the Task Group on the Biological Effects of Space Radiation.

r. julian preston – BIO
Toohey_D Richard E. Toohey

Telephone: (301) 657-2652



received his PhD in physics from the University of Cincinnati in 1973. He spent the first part of his career at Argonne National Laboratory in both research and operational health physics. He recently retired from Oak Ridge Associated Universities, where he served as director of the Radiation Internal Dose Information Center, as Senior Health Physicist for the Radiation Emergency Assistance Center/Training Site, Director of Dose Reconstruction Programs, and Associate Director of the Independent Environmental Assessment and Verification Program. He is currenly employed by M.H. Chew and Associates.

He is certified in comprehensive practice by the American Board of Health Physics, was the 2008 to 2009 President of the Health Physics Society, is a member and director of NCRP, Treasurer of the International Radiation Protection Association, and Chair of the Scientific Advisory Committee for the U.S. Transuranium and Uranium Registries. His specialties are internal radiation dosimetry, dose reconstruction, and radiological emergency response. Dr. Toohey has 125 publications in the open literature, and is a retired Lt. Colonel, U.S. Army Reserve.

richard e. toohey – BIO
Roy E. Shore Roy E. Shore

Telephone: (301) 657-2652


was a Professor and Chief of the Epidemiology Division at New York University School of Medicine before going to the Radiation Effects Research Foundation (RERF) in Hiroshima-Nagasaki as Vice Chairman and Chief of Research. He is an author of ~100 radiation-related publications and is currently working with other RERF investigators on studies of radiation and various diseases.

He has served on numerous governmental and scholarly committees, including as a long-time member of the International Commission on Radiological Protection and NCRP, and has served on various committees or task groups for the United Nations Scientfic Committee on the Effects of Atomic Radiation, the World Health Organization, the National Academy of Sciences, the National Cancer Institute, and the U.S. Environmental Protection Agency, among others. His interests include the effects of radiation on both cancer and noncancer disease incidence, and understanding the epidemiologic and biological modification of radiation effects by various environmental, genetic and age factors.

roy e. shore – BIO

Active Staff Consultants

CohenS Sarah S. Cohen

Telephone: (301) 657-2652

Sarah S. Cohen

CohenSis an epidemiologist and biostatistician with EpidStat Institute and a consultant to the NCRP with over 15 y of experience in the design and conduct of epidemiological studies. Dr. Cohen’s areas of expertise include cancer epidemiology, obesity, pharmacoepidemiology, occupational health, and radiation health effects. She has spent nearly 15 y collaborating on epidemiologic studies of worker health in relation to radiation exposure including cohort assembly and tracing as well as statistical modeling. In addition, Dr. Cohen is currently Adjunct Assistant Research Professor of Medicine in the Division of Epidemiology within the Department of Medicine at the Vanderbilt University School of Medicine.

Sarah S. Cohen – BIO

  • Million Person Study
Gray J Joel E. Gray

Telephone: (301) 657-2652


Gray J

is Professor Emeritus, Mayo Clinic College of Medicine and President of DIQUAD, LLC (Dental Image Quality and Dose), a firm that evaluates dental image quality and dose through the mail. Dr. Gray received his BS in Photographic Science and Instrumentation in 1970, an MS in Optical Sciences in 1974, and a PhD in Radiological Sciences from the Institute of Medical Sciences, University of Toronto in 1977.

He served as a Diagnostic Medical Physicist at Mayo Clinic Rochester for 20 y, helped develop and obtain U.S. Food and Drug Administration (FDA) approval for Lorad's (now Hologic) first digital mammography system, and assisted in the development of the microStar patient dosimetry system using optically stimulated dosimetry material while at Landauer, Inc. After leaving Landauer, Dr. Gray founded DIQUAD and continues to operate that business today.

Dr. Gray published the first two books on quality control in medical imaging in 1976 under contract to FDA while in graduate school. Dr. Gray is the primary author of the first quality control text (Quality Control in Diagnostic Imaging—A Quality Control Cookbook) which is in use worldwide and has been translated into Chinese.

His primary areas of interest include image quality in medical and dental imaging, and optimization of image quality and radiation dose. He serves as a consultant to healthcare organizations and industry. Dr. Gray has served on many national and international advisory committees, including the International Commission Radiological Protection (Committee 3, Radiation Protection in Medicine) and is active in projects with the International Atomic Energy Agency (IAEA) and the World Health Organization. He has co-authored eight publications for the IAEA including educational programs and taught courses for the IAEA in several countries. He has over 170 publications in refereed journals and numerous book chapters, and presented lectures and refresher courses in the United States and overseas. He has visited over 40 countries for both business and pleasure.

Dr. Gray was responsible for starting the first Medical Physics Residency Program at Mayo Clinic in 1990. He has mentored masters and doctoral students, and Medical Physics residents.

He was elected to NCRP in 1986 and has served on numerous committees producing NCRP Report No. 99, Quality Assurance for Diagnostic Imaging; Report No. 147, Structural Shielding Design for Medical Imaging Facilities; and Report No. 160, Ionizing Radiation Exposure of the Population of the United States. He has served as a Technical Consultant for NCRP Commentary No. 20, Radiation Protection and Measurement Issues Related to Cargo Scanning with Accelerator-Produced High-Energy X Rays; NCRP Report No. 172, Reference Levels and Achievable Doses in Medical and Dental Imaging: Recommendations for the United States; and is presently serving on Scientific Committee 4-5 on radiation protection in dentistry supplement, in that capacity. After serving 18 y on the Council he was named a Distinguished Emeritus Member in 2005.

Dr. Gray is a Fellow of the American Association of Physicists in Medicine (AAPM) and the American College of Medical Physics. In 2010 he received the Lifetime Achievement Award from the Upstate New York Association of Medical Physicists and in 2011 the Edith Quimby Lifetime Achievement Award from the AAPM.

joel e. gray – BIO

Michael P. Grissom Michael P. Grissom

Telephone: (301) 657-2652

Michael P. Grissom


MICHAEL P. GRISSOM is a Technical Staff Consultant for NCRP and is the President of MPG-HP, Inc., Riverside, California a private consulting firm. He is a recognized authority on operational health physics issues, particularly related to radiation protection in management, military, reactor, medical, and accelerator operations. During 20 y of service in the U.S. Navy, Mr. Grissom served as a Radiation Safety/Laser Safety Officer (hospital) and provided Radiation Health Officer support to the Naval Radiological Controls Program (propulsion, industrial and weapons).

Mr. Grissom conducted research in biophysics and radiobiological effects at the Armed Forces Radiobiology Research Institute, Bethesda, Maryland as a junior then senior scientist and served as the Director of Medical Records Search for the Navy Nuclear Test Personnel Review, Office of the Chief of Naval Operations, Washington, DC. Mr. Grissom provided support to the Effluent and Dose Assessment Group, Three Mile Island Unit 2 Recovery Team in 1979 to 1980. He has delivered numerous presentations at scientific and professional society meetings. In 2012, Mr. Grissom became a Fellow of the Health Physics Society (HPS).

He previously received the HPS Volunteer Award for services associated with the Medical Health Physics Section and is a Past President of the HPS Accelerator Section. He also served in a number of positions for Stanford University over a period of 16 y at the Stanford Linear Accelerator Center National Accelerator Laboratory, Menlo Park, California including Department Head, Operational Health Physics, and Assistant Associate Director for Environment, Safety and Health.

Michael P. Grissom – BIO

Rosenstein Marvin Rosenstein

Telephone: (301) 657-2652



is a consultant, currently concentrating on the preparation of scientific reports produced by NCRP in all subject areas. From 1982 to 1995, he was Director, Office of Health Physics at the Center for Devices and Radiological Health, U.S. Food and Drug Administration. He also served in a number of scientific and management positions related to radiation protection during his 33 y career as a Commissioned Officer in the U.S. Public Health Service, from 1962 to 1995. He received a BS in Chemical Engineering (University of Maryland, 1961), an MS in Environmental Engineering (Rensselaer Polytechnic Institute, 1966) and a PhD in Nuclear Engineering (University of Maryland, 1971). His technical work has concentrated on radiation dosimetry, particularly with regard to x rays used for medical diagnosis, epidemiological studies of exposed populations, and public radiation emergencies.

He is a Distinguished Emeritus Member of NCRP (after serving as a Council member for 18 y), and an Emeritus member of Committee 3 (Protection in Medicine) of the International Commission on Radiological Protection [after serving on Committee 3 for 28 y (1985 to 2013)]. He was also a member of the International Commission on Radiation Units and Measurements report committee that produced Report 74, Patient Dosimetry for X Rays Used in Medical Imaging.

marvin rosenstein – BIO

Smith J James M. Smith

Telephone: (301) 657-2652

James M. Smith

Smith J

is a consulting physicist and an adjunct professor at Emory University’s Rollins School of Public Health. He began his career as a research physicist at the former RCA Space Center in Princeton, New Jersey, and later became associate research professor at the University of Utah School of Medicine. He was founding chief of the Radiation Studies Branch at the U.S. Centers for Disease Control and Prevention (CDC), where he also held a Distinguished Scientist appointment. In 1994 he received the U.S. Public Health Service Superior Service Award for establishing CDC as major international focus for radiation studies.

Dr. Smith has consulted on nuclear threat countermeasures for the International Atomic Energy Agency in Vienna, the White House Office of Science and Technology Policy, and the G-7 Global Health Security Action Group. He traveled extensively advising public health officials and nongovernmental organizations in the aftermath of Chernobyl and Fukushima nuclear crises. Currently, he is staff consultant to NCRP’s Scientific Committee on Emergency Responder Dosimetry. He received his MS in theoretical physics and PhD in experimental physics from West Virginia University and completed his post-doctoral research at Florida State University’s Institute of Molecular Biophysics.

James M. Smith – BIO

Townsend-L Lawrence W. Townsend

Telephone: (301) 657-2652

Lawrence W. Townsend

Townsend-Lis the Chancellor's Professor and Robert M. Condra Professor of Nuclear Engineering, University of Tennessee, Knoxville. He has a BS in Physics from the U.S. Naval Academy, and an MS in Physics (experimental nuclear) from the Naval Postgraduate School. After obtaining his MS, he served for 7 y as a nuclear submarine engineer. After leaving the Navy, he obtained a PhD in Physics (theoretical nuclear) from the University of Idaho. After a short stint as a Research Assistant Professor of Physics at Old Dominion University, he became a National Aeronautics and Space Administration (NASA) Research Scientist and Senior Research Scientist where his research has focused on nuclear interactions of cosmic rays and their implications for space radiation shielding and crew protection. For these efforts, he was awarded a NASA Scientific Achievement Medal. In 1995 he retired from NASA and entered academia at the University of Tennessee where he continues to do research on space radiation interactions, transport, and their effects. In 1998 he served as the Organizing Committee Chair for the NCRP Annual Meeting and was elected a Member of Council and was appointed as a Distinguished Emeritus Member of Council in 2010. He has served as a member of Scientific Committee 75, chair of Scientific Committee 1-7, and consultant for Scientific Committee 1-24 (phase I).

Lawrence W. Townsend – BIO

Vetter Richard J. Vetter

Telephone: (301) 657-2652



is Professor Emeritus and former Radiation Safety Officer at the Mayo Clinic in Rochester, Minnosota. He received his BS and MS degrees in Biology from South Dakota State University and his PhD in Health Physics from Purdue University. He is board certified by the American Board of Health Physics and the American Board of Medical Physics. He served on the Purdue University faculty from 1970 to 1980 and the Mayo Clinic staff and faculty from 1980 to 2010. Dr. Vetter is a member of the National Academies Nuclear and Radiation Studies Board, the Government Liaison for the Health Physics Society (HPS), and a member of the Executive Council of the International Radiation Protection Association. He is a Fellow of HPS and the American Association of Physicists in Medicine and received the HPS Founders Award.

He is past Editor-in-Chief of Health Physics, past president of HPS, past president of the American Academy of Health Physics, and author or coauthor of more than 220 publications, books, book chapters, and other articles. He served as Vice Chair of the U.S. Nuclear Regulatory Commission Advisory Committee for Medical Uses of Isotopes and member of the Radiation Advisory Committee of the U.S. Environmental Protection Agency Science Advisory Board. He served on the Board of Directors of NCRP, Chair of the NCRP Nominating Committee, and Chair of three and member of two NCRP scientific committees resulting in four NCRP reports and one NCRP statement. Dr. Vetter has received outstanding alumnus awards from South Dakota State University, the Purdue School of Pharmacy and Pharmacal Sciences, the Purdue School of Health Sciences, and the Purdue College of Health and Human Sciences.

richard j. vetter – BIO


Administrative Staff

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Last modified: March 9, 2017