Meet the "Ask the Experts" Editors

by Emily Caffrey, Ask the Experts Editor

Do you have a question about radiation protection or radiation safety? Did you see something related to radiation in the media and want to know if it is accurate? Curious about the radiation emitted by your cell phone? Have a medical procedure and want to know your risk? You have come to the right place! Since the inception of the Ask the Experts feature a number of years ago, over 13,000 questions have been fielded by our dedicated team of volunteer experts. Search through the answers here, or check out a specific category to see if your question has already been answered!

Still have a question? Submit it here and get an answer from an expert! Are you a member of the media with a specific question? Contact HPS Society Operations Editor Craig Little.

Bios and photos of the ATE editors follow.

Editor, "Ask the Experts"

Emily Caffrey graduated in 2016 with her PhD in radiation health physics from Oregon State University. She is now a scientific consultant with Risk Assessment Corporation, specializing in performance assessments and independent environmental dose and risk assessments. She helped in the development of a new health physics program at the University of Alabama at Birmingham in 2016 and is actively involved in the Alabama Chapter of the HPS, serving as its president from 2017 to 2019. Emily holds a BS in nuclear engineering from Oregon State University and during her academic tenure was selected as an ARCS Scholar and an Endeavor Fellow for Australia's Nuclear Science and Technology Organization. She is also active in the National Council on Radiation Protection and Measurements (NCRP), where she served on SC1-25 examining recent literature on the linear no-threshold model. Her technical expertise includes ionizing radiation dosimetry, statistics, and communications.


Kamran Vaziri received his PhD in nuclear physics from Utah State University in 1987, doing his doctoral thesis work at Los Alamos National Laboratory. He then worked on nuclear physics experiments at the University of Colorado Nuclear Physics Laboratory and later joined Rensselaer Polytechnic Institute, working on experiments at Brookhaven National Laboratory, Jefferson Lab, and Massachusetts Institute of Technology Bates Linear Accelerator Center. Kamran joined Fermilab's Radiation Physics group in 1992. He has been working on radiation physics problems and reviews of different accelerators and experiments. As a radiation physicist, his responsibilities include radiation physics modeling and calculation in support of experiments and accelerator designs, site radiation measurements and instrumentation, environmental measurements, regulatory issues, and serving as Fermilab radiation safety interlocks coordinator and national emission standards for hazardous air pollutants (NESHAP) coordinator. He is the radiation safety coordinator for the NOvA experiment at Fermilab. Kamran has coauthored more than 100 scientific and technical papers regarding radiation physics and nuclear physics. He is an occasional book and article reviewer for Health Physics. He has taught a radiation physics course at the US Particle Accelerator School and has taught radiation monitoring and environmental monitoring courses at the HPS professional development school. He is the past president of the HPS Accelerator Section.

Cell Phones, Radiofrequency Radiation, and Powerline Fields

Kenneth R. Foster received a PhD degree in physics from Indiana University, Bloomington, in 1971. After serving with the US Navy from 1971 to 1976, he joined the University of Pennsylvania, where he is currently professor emeritus of bioengineering. His technical research has focused on health and safety as related to radiofrequency energy, with approximately 160 papers related to interactions of electromagnetic fields with biological systems ranging from biophysical mechanisms of interaction to heating of tissue by microwave energy. In addition, he has written and spoken extensively on a broad range of topics including medical technology and health, risks of technology, and ethical issues related to biomedical technology. As well as being emeritus member of the HPS, he is coeditor in chief of BioMedical Engineering OnLine. He is a registered professional engineer, a fellow of the Institute of Electrical and Electronics Engineers, and a fellow of the American Institute of Medical and Biological Engineering. In 2016, he received the d'Arsonval Award from the Bioelectromagnetics Society for contributions to the field of bioelectromagnetics. He has been active for many years in committees that set limits for human exposure to electromagnetic fields and other issues related to health and safety.

Consumer Products

Orhan SuleimanCharles (Charlie) Wilson is a certified safety professional and certified laser safety officer with an MS in health physics and PhD studying environmental health physics from Louisiana State University (LSU). He began his career working with the LSU Radiation Safety Office and eventually became the LSU Particle Accelerator's radiation safety officer. Charlie is currently the associate radiation safety officer at the University of Missouri, helping oversee a broad scope program including research, veterinary, and medical uses of radiation. He also serves on ANSI Z136 Subcommittee SSC-8. Charlie is an active member of the HPS, serving in many roles including program committees, task forces, Student Support chair, Society Support chair, president of the Early Career Section, president of the Deep South Chapter, and board member of the Greater Saint Louis Chapter.

Decommissioning and Radioactive Waste Disposal

Nick Altic is a certified health physicist and project manager with the Oak Ridge Associated Universities (ORAU). His primary responsibilities include management and the technical direction of independent verification activities at radiologically remediated sites for the US Department of Energy, US Nuclear Regulatory Commission, and other federal entities. In addition to his experience at ORAU, Nick also served as the instrumentation program manager for a commercial power reactor. Areas of expertise include instrumentation, nondestructive assay techniques, and implementation of MARSSIM-based radiological surveys. He holds graduate and undergraduate degrees in health physics from Idaho State University and Purdue University, respectively.

Environmental and Background Radiation

Jan Johnson is a certified health physicist with over 50 years of experience in radiation health physics including radiation worker training, environmental and occupational radiation protection, and radiation risk assessment. She was a member of the faculty at Colorado State University (CSU), initially as a research associate, eventually managing the CSU Environmental Health Services Department. Since leaving CSU in 1995, she has worked as a consultant in radiation protection, primarily involving the uranium-recovery industry. She was a member of the Environmental Protection Agency Science Advisory Board Radiation Advisory Committee from 1995 to 2003 and served on the Colorado Radiation Advisory Committee until 2013. She is a fellow of the HPS and received the Society's Founders Award in 2013.

Homeland Security and Security Screening

Craig Marianno is an assistant professor in the Department of Nuclear Engineering at Texas A&M University and the deputy director for the Center of Nuclear Security Science and Policy Initiatives. Prior to coming to Texas A&M, he was a contractor for the National Nuclear Security Administration where he served on many of its emergency response teams, including the Consequence Management Response Team, Search Response Team, Radiological Assistance Program, and Aerial Measuring System. His research team at Texas A&M focuses on emergency-response health physics, radiation detection, and nuclear security.

Industrial Radiation and Radiation Materials Science

John Hageman is a certified health physicist and was the radiation safety officer and principal scientist from Southwest Research Institute® (SwRI®) until his recent retirement. He has a BS in physics from the University of Texas (UT) at Arlington and an MS in radiological sciences-medical health physics from the UT Health Science Center at San Antonio. At SwRI he was responsible for the use of a large variety of radionuclides under a broad radioactive material license issued for research and development. He was also responsible for the safe operation of a large variety of radiation-producing machines used for laboratory analysis and the High-Level Radiation Effects Facility, which is licensed for sealed sources of 60Co and 137Cs. He holds a patent on a charged-particle powered battery and has consulted in the design analyses for hot cells and accelerator shielding. He was a manager with the Center for Nuclear Waste Regulatory Analyses at SwRI for several projects for the NRC's high-level radioactive waste program. He also worked with Westinghouse Electric Corporation as a nuclear plant engineer, where he supervised plant operations and the training of Naval officers at the Idaho Naval Reactors Facilities. For the HPS, he is an associate editor of Operational Radiation Safety (1999–present), was a member of the Board of Directors (2003–2005), became a fellow in 2004, and served as treasurer-elect/treasurer (2009–2012).

Instrumentation and Measurements and Radiation Fundamentals

George Chabot is currently professor emeritus at the University of Massachusetts Lowell, where he previously served as professor of radiological sciences in the Physics Department and, for many years, as radiation safety officer for the university. He serves as a consultant in radiation science and radiation protection to public utilities, industry, medical facilities, government agencies, and others. His earlier work experience includes employment as an analytical organic chemist in private industry and six years of work as a radiochemist and in the training group of the Radiological Health Branch of the US Public Health Service (now the FDA). He has been active in the HPS, the AAHP, the NCRP, and other scientific organizations. His formal education includes a BA degree in chemistry from Harvard University, an MS in industrial hygiene/radiological health from the Harvard School of Public Health, and a PhD in analytical chemistry from the University of Lowell. He is the author of numerous publications that include refereed journal articles, book chapters, reports, and manuals dealing with various aspects of radiation science and protection, especially in areas of radiation dosimetry and radiation measurement.

Lasers, Infrared, and Ultraviolet Radiation

Paul Charp is a governmental health physicist with over 30 years of experience in the fields of environmental health physics, radiation biology, and radiation safety. He has evaluated the public health impacts from hazardous waste sites contaminated with radioactive materials, including sites related to the Manhattan Project as well as uranium mining and milling. Besides working in the public health sector, he is also a part-time instructor in the radiological and nuclear engineering and medical physics programs at Georgia Tech. While in the former Biology Division at the Oak Ridge National Laboratory, Paul studied the effects of ultraviolet light on the damage and repair of human cells at the molecular and biochemical levels. A member of the HPS since 1989, he has served on many committees and is a member of the Homeland Security, Medical Physics, and Environmental/Radon Society Sections.

Medical and Dental Equipment and Shielding

Kenneth Duke LovinsKennith "Duke" Lovins is a medical health physicist and is certified by the ABHP. He has an MS degree in health physics from the University of Cincinnati and a BHS degree in radiological health science from the University of Kentucky. He has been employed by Unicon Physics, Inc., in Cincinnati, Ohio, since 1995 and provides consulting services to hospitals and clinics. His responsibilities include performing nuclear medicine department audits, developing quality-assurance programs for diagnostic radiology departments, performing quality-control testing on x-ray equipment, and providing training and membership on a number of radiation safety committees. Previously, he was a health physicist at the VA Medical Center in Lexington, Kentucky. He is a member of the HPS, the AAPM, the Conference of Radiation Control Program Directors, and the Cincinnati Radiation Society. He was a member of the joint HPS/AAPM working group to develop an ANSI standard for fetal radiation dose calculations.

Medical and Dental Patient Issues

Deirdre Elder is a certified health physicist with an undergraduate degree in engineering physics from Colorado School of Mines and a master's degree in radiological health sciences (health physics) from Colorado State University. She is the radiation safety manager and laser safety officer for University of Colorado Hospital, Longs Peak Hospital, Highlands Ranch Hospital, and other facilities in the UCHealth system. Her responsibilities include providing radiation safety and laser safety training to residents, fellows, and staff. Deirdre is an active member of the HPS and has served on several committees. She was the president of the Central Rocky Mountain Chapter and secretary/treasurer of the Medical Section. She is also a certified medical laser safety officer and a member of the Laser Institute of America.

Medical and Dental Patient Issues

Victoria (Vicki) Morris is a retired medical radiation safety officer. Currently, she is a consultant. A major portion of her consulting assignments involves auditing nuclear medicine and radiation oncology programs. Vicki has a bachelor of science in environmental health and a master of science in health sciences, both from Purdue University. Vicki is certified by the ABHP and is currently a member of the ABHP Board. She is a fellow of the HPS and has served on several Society committees, including serving one term as a board member and one term as president for the Medical Health Physics Section. Vicki is active with local chapters of the HPS. She served 22 years on the board of the Cincinnati Radiation Society, including one term as president and three terms as secretary. In addition, Vicki served on the state of Ohio Radiation Advisory Board and several Ohio radiation regulation development committees.

Nuclear Medicine Patient Issues

Xiaoqian (Carol) Wen is a certified health physicist and radiation safety officer at Christiana Care Health System in Newark, Delaware, where she oversees the radiation safety operations and activities for multiple hospitals and outpatient imaging sites. Carol started her career working as a radiation safety specialist at the University of Cincinnati (UC) after receiving her master's degree in health physics from UC. Later she worked as a health physicist and medical health physicist at the University of Maryland, Baltimore, and the University of Pennsylvania, respectively. Carol is passionate about protecting patients, caregivers, the general public, and the environment from unnecessary radiation exposure and is engaged with discussions and problem solving for all levels of radiation protection issues throughout Christiana Care Health System. Currently, Carol is a member of the HPS, the AAPM, the Delaware Valley Society for Radiation Safety, and the Delaware Valley Chapter of AAPM.

Nuclear Power and Radiation Accidents

Joel Cehn is a native of Waterbury, Connecticut. He received his bachelor of science degree in physics from Worcester Polytechnic Institute in Massachusetts and a master of science degree in engineering from North Carolina State University. As an independent, board-certified health physicist, Joel measures radiation levels around nuclear power plants, research laboratories, and hospitals and at many varied locations in the United States and abroad. His work involves measurements of radioactivity in soil and groundwater, as well as measuring and estimating radiation doses to workers and the public. He has written and spoken extensively on exposure to radiation and its effects and has conducted numerous training sessions. He has served as an expert witness in several cases involving radiation and, in his spare time, creates educational kits for teaching about radiation. Joel lives in Central California and is past president of the local HPS chapter.

Popular Culture and Radiation

Norman Dickinson brings a wealth of experience to Ask the Experts, including having spent time in the nuclear Navy, in state and local government, and serving as an academic radiation safety officer for several years. His education in geology (BS and MS) has given him a lifelong fascination with naturally occurring radioactive materials (coincidentally also nicknamed NORM), and he has done a great deal of work with isotope geologists and environmental geochemists in a variety of field locations over the years. In addition, as someone who's curious about virtually everything, Norm has picked up quite a bit of oddball information over the years.
Norm also maintains an interest in the way radiation and nuclear topics are portrayed in the popular media—while he doesn't consider himself to be a masochist, he does find himself drawn to movies, TV shows, and the like in which these play a major role.
Norm lives in the Midwest and considers himself to be "partially retired."

Pregnancy and Radiation

Barbara L. Hamrick received a BS and MS in physics from the University of California (UC) Irvine in 1985 and 1987, respectively. She earned a law degree in 1999 from Loyola Law School in Los Angeles and is an active member of the California State Bar. In 2002, she was certified by the ABHP. She is currently the radiation safety officer at UC, Irvine Health, where she manages the Radiation Safety Program, keeping the environment safe for patients, workers, and the public. Prior to joining the UC Irvine Health team, she spent nearly 20 years as a health physicist in regulatory agencies, including the US Nuclear Regulatory Commission, Los Angeles County Radiation Management, and the California Department of Public Health. Professional activities include serving on the US Environmental Protection Agency's Radiation Advisory Committee, service on three committees of the National Academy of Sciences, and serving as a council member on the NCRP. She is also a past president of the HPS.

Regulations, Policies, and Standards

Margaret Cervera came to health physics accidentally after a winding career path that included work in the service industry and veterinary medicine, as well as stints as a research microbiologist, pharmaceutical chemist, and cell biologist. Her formal education includes a BS in microbiology and chemistry with a certificate in biotechnology from Colorado State University. She went on to complete her master's degree in health physics at Colorado State University, serving along the way as president of the student chapter of the HPS. Upon graduation in 2009, Margaret quit her job as a forklift driver loading beer at the Anheuser-Busch brewery and reported for duty as a staff health physicist at the NRC. Her professional specialty is physical security of byproduct materials, but occasionally she has branched out into nuclear reactor regulation.


Fred BaesRamesh Bobbu received a bachelor of technology in computer science and engineering at the University of Madras in 1999. His career in software development began in 2002, and he has worked in various roles in that field for close to two decades. He is currently working as a senior developer/team lead. In 2021, Ramesh became the webmaster for the HPS.

Technical Editor

Craig Little has 40 years of experience in radioecology and radiation protection. He did his graduate research in the grasslands surrounding the Rocky Flats Plant. During his career, Craig has worked on radiological issues for the DOE, the NRC, the EPA, the US Department of Defense, and the National Institute for Occupational Safety and Health. He established the Oak Ridge National Laboratory office in Grand Junction, Colorado, in support of the DOE Uranium Mill Tailings Remedial Action project and led that office for 18 years. He is currently president and senior scientist for Two Lines Inc. Radiation Risk Consultants. He is focused on occupational and environmental dose modeling, licensing of new uranium-production facilities, training of radiation workers, technical editing, and litigation support for a variety of private clients. He is a member of the Radiation Advisory Committee for the Colorado Department of Public Health and Environment. He currently serves as editor in chief of Operational Radiation Safety and is an associate editor of Health Physics. He also serves as federal agency liaison for the HPS.

Editorial Associate

Sharon Hebl     
Sharon Hebl