SC 6-12: Development of Models for Brain Dosimetry for Internally Deposited Radionuclides


SC 6-12 will prepare a commentary that describes new methodological approaches to obtain dose to the brain following intakes of radionuclides. This will help ongoing efforts with regard to the U.S. Department of Energy (DOE) and the National Aeronautics and Space Administration focusing on the effects of high linear-energy transfer (LET) particles in the brain, as well as provide new knowledge on brain dosimetry relevant to protection that has not been available heretofore. Currently, there are no International Commission on Radiological Protection models that provide radiation dose to brain tissue following intakes of radionuclides. However, cohorts of DOE workers (e.g., from Los Alamos National Laboratory, Mallinckrodt Chemical Works, Mound, and Rocketdyne) with intakes of radionuclides that give high-LET dose to brain tissue from alpha-particle emitters amid a low-LET dose from external gamma rays provide a human population receiving radiation somewhat analogous to the exposures received by astronauts in outer space. Of interest is to look at alpha-particle dose to the brain and subsequent risk of dementias, as well as cancer. Radionuclides of interest include polonium, radium, plutonium, americium and uranium, and validation that these cross the blood-brain barrier has come from autopsy material in the U.S. Transuranium and Uranium Registries and Litvinenko. While not equivalent to heavy ion exposures from galactic cosmic rays, using these cohorts has the advantage of providing information after low dose rate (years) for high-LET particles, and measures effect in humans, not mice. In the commentary, the Committee will expand on currently available biokinetic models to include brain dose explicitly.


To prepare a focused commentary that describes new methodological approaches to obtain dose to the brain following intakes of alpha particle-emitting radionuclides, including modifying currently available biokinetic models to include brain dose explicitly.



Richard Leggett

Leggett Ris a research scientist in the Environmental Sciences Division at Oak Ridge National Laboratory (ORNL). He received his PhD in mathematics from the University of Kentucky in 1972 and taught mathematics at the Ruhr University in Bochum, Germany, and the University of Tennessee before joining the Health Physics Division at ORNL in 1976. His main research interest is in physiological systems modeling, with primary applications to the biokinetics and dosimetry of radionuclides and radiation risk analysis. He is a member of Committee 2 of the International Commission on Radiological Protection (ICRP) and the ICRP Task Group on Internal Dosimetry. His physiological systems models of the human circulation, skeleton, and gastrointestinal transfer and his systemic biokinetic models for a number of elements are used by ICRP as dosimetry and bioassay models. He is the author of ICRP Publication 70, Basic Anatomical and Physiological Data for Use in Radiological Protection: The Skeleton and co-author of a number of other ICRP reports including the series of documents on doses to members of the public from intake of radionuclides (1989 to 1996), the updated Reference Man document (2002), and the Human Alimentary Tract Model (2006). He has authored over 100 open literature publications and in 1995 was named ORNL Author of the Year for the paper, β€œAn Age-Specific Kinetic Model of Pb Metabolism in Humans.”

Richard Leggett , Chairman

Sergey Y. Tolmachev

is an Associate Research Professor in the College of Pharmacy, Washington State University (WSU), where he directs the U.S. Transuranium and Uranium Registries (USTUR) Research Center and the National Human Tissue Repository (NHRTR). The USTUR/NHRTR is a federal-grant-funded human tissue research program providing long-term follow-up of actinide biokinetics and potential health effects in nuclear workers (volunteer registrants) with accidental internal depositions of actinide elements. Prior to the directorship, Dr. Tolmachev managed the USTUR's radiochemistry laboratory operations and research in the fields of actinide radiochemistry and mass spectrometry, in support of internal dosimetry and actinide biokinetics research.

Dr. Tolmachev is a member of the Board of Directors of the Herbert M. Parker Foundation at WSU. He serves on the Editorial Board of the Japanese Journal of Health Physics and is a current member of several professional societies nationally and internationally. Dr. Tolmachev is the Guest Editor for Health Physics journal's special issue dedicated to the USTUR's 50 y of operation and research.

Dr. Tolmachev has over 20 y of experience in the development of analytical methods, and in actinide analyses of environmental and biological samples. He is an expert in state-of-the-art analytical instrumentation, including various types of inductively coupled plasma mass spectrometers (ICP-MS), high performance liquid chromatography, and alpha-spectrometry systems. Dr. Tolmachev earned his Diploma of nuclear technology engineer (MS equivalent) at the Mendeleyev University of Chemical Technology of Russia (Moscow) in 1993, majoring in radiation and radiochemistry. His Master's Thesis project was completed at the Joint Institute for Nuclear Researches (JINR) in Dubna, Russia. After graduation, he joined the Radioanalytical Research Group at JINR. In 1997, he was awarded a scholarship by the Ministry of Education, Culture and Sport of Japan for research and doctoral study at Kyushu University (Fukuoka) in the field of Environmental Radiochemistry/Radioecology. His research focused on 210Po, 36Cl, and 3H determination and behavior in the environment. He developed a radioanalytical protocol for 36Cl determination by projectile x-ray accelerator mass spectrometry. Dr. Tolmachev was awarded the degree of Doctor of Science (PhD equivalent) in 2001. He continued his scientific career with two postdoctoral fellowships in Japan: at the Japan Atomic Energy Research Institute (Tokai-mura), Department of Health Physics; and at the National Institute of Radiological Sciences (Chiba), Research Center for Radiation Safety. During this period, his research focused on applying ICP-MS techniques for uranium (234U, 235U, 238U) and 232Th isotopic determination in human body fluids, actinide biokinetics, and internal dose assessment. He established a rapid automated flow-injection ICP-MS method for uranium isotopic determination for the purpose of internal dose assessment. Dr. Tolmachev conducted a milestone study of the concentration and daily excretion of uranium in urine of Japanese (to better define the exposure of the Japanese population to natural uranium). His Japanese research also included method development to apply sector field ICP-MS to measure 226Ra in environmental samples.

Dr. Tolmachev is an internationally recognized scientist. In addition to directing the USTUR, he is an Adjunct Professor at the Department of Chemistry of Laval University (Canada); a Visiting Professor at Kyushu University, Radioisotope Center (Japan); and Technical Advisor at Kyushu Environmental Evaluation Association (Japan). While working at WSU, he has established active scientific collaborations with the European Radiation Dosimetry Group WG-7 on Internal Dosimetry, Karlsruhe Institute of Technology (Germany), Public Health England (United Kingdom), and Radiation Protection Bureau at Health Canada, as well as with the leading U.S. laboratories such as Pacific Northwest National Laboratory and Radiation Emergency Assistance Center/Training Site.

Sergey Y. Tolmachev , Vice Chairman

Maia Avtandilashvili

is an Assistant Research Professor in the College of Pharmacy, Washington State University. She earned her Diploma with Honors (equivalent to MS) in Experimental Nuclear Physics from I. Javakhishvili Tbilisi State University (Republic of Georgia) and PhD in Health Physics from Idaho State University (ISU). Prior to her doctoral study, Dr. Avtandilashvili worked in the Physics Department of Tbilisi State University and was actively involved in a number of international research projects, including the International Atomic Energy Agency's (IAEA) Regional Project "Marine Environmental Assessment of the Black Sea Region"; the Advanced Accelerator Applications – Dose Conversion Coefficients project funded by the U.S. Department of Energy; the Tbilisi Radon Assessment Initiative supported by the U.S. Civil Research and Development Foundation; etc. In 1999, she was awarded an IAEA Fellowship in Germany.

After completing her PhD at ISU in 2011, Dr. Avtandilashvili joined the U.S. Transuranium and Uranium Registries (USTUR) research team. Her current research focuses on modeling of actinide biokinetics using unique human data from former nuclear workers (volunteer donors to the USTUR) with accidental internal depositions of actinide elements. Dr. Avtandilashvili applies advanced statistical analysis methods to bioassay and tissue radiochemical analysis data from the USTUR donors (1) to test, validate, improve and parameterize biokinetic models for radiological protection; (2) to evaluate uncertainties in internal dose estimates in support of epidemiological studies; and (3) to investigate effects and mechanisms of actinide decorporation using chelating agents. She is also responsible for management and population of the USTUR health physics database.

Dr. Avtandilashvili is a member of the European Radiation Dosimetry Group Working Group 7 on "Internal Dosimetry." She also serves as an Editorial Board member of the Austin Biometrics and Biostatistics journal and as a Guest Co-Editor of the USTUR special issue of the Health Physics journal.

Maia Avtandilashvili


Eckerman K

in Radiological Physics from Northwestern University in 1972. Dr. Eckerman joined the Oak Ridge National Laboratory in 1979 as leader of the Dosimetry Research Group after working at Argonne National Laboratory and with the U.S. Nuclear Regulatory Commission. He is a member of Committee 2 of the International Commission on Radiological Protection and Chairman of its Task Group on Dose Calculations. In 1999 he received the Distinguished Scientific Achievement Award from the Health Physics Society and in 2001 the Loevinger-Berman Award from the Society of Nuclear Medicine.

keith f. eckerman
Sgouros G


Sgouros G

is Professor of Radiology, Oncology and Radiation Oncology, Director of Radiopharmaceutical Dosimetry Section of the Division of Nuclear Medicine, Johns Hopkins University, School of Medicine. He has been principal investigator or program leader on numerous grants with over 20 y experience in modeling and dosimetry of internally administered radionuclides with a particular emphasis on patient-specific dosimetry, alpha-particle dosimetry, and mathematical modeling of radionuclide therapy. Dr. Sgouros' laboratory is currently engaged in preclinical research investigating targeted alpha-emitter therapy of metastatic cancer. He is author on more than 100 peer-reviewed articles, as well as several book chapters and review articles. He is chairman of the Medical Internal Radionuclide Dose Committee of the Society of Nuclear Medicine, as well as steering committee member, of the American Association of Physicists in Medicine, Task Group on Internal Emitter Dosimetry.

He has served as chairman of the Dosimetry and Radiobiology Panel at a U.S. Department of Energy Workshop on alpha-emitters in medical therapy and, in the early 1990s, provided the physics/dosimetry support for the first Food and Drug Administration-approved human trial of targeted alpha-emitter therapy. He is also a member of the scientific advisory board of AREVA Med (Bethesda, Maryland), which is developing 212Pb-based alpha-emitters for targeted cancer therapy. Program areas of interest: medicine; dosimetry and measurement; education, risk communication, and outreach.

george sgouros



is a Professor of Radiation Oncology and Radiology at Northwestern University Feinberg School of Medicine in Chicago. She and her group have been involved in studies of molecular consequences of radiation exposure, late tissue effects associated with radiation, and the use of radiation-inducible nanomaterials for cancer imaging and therapy. Dr. Woloschak also teaches radiation biology to radiation oncology and radiology residents, cardiology trainees, and graduate students and manages the Advanced Grant Writing Workshop for the Radiological Society of North America (RSNA). She earned her PhD in medical sciences from the University of Toledo (Ohio) and did post-doctoral studies in molecular biology at the Mayo Clinic. She has served on review panels for various federal agencies including the National Institutes of Health, the National Aeronautics and Space Administration, the U.S. Department of Energy, RSNA, the U.S. Army Medical Research and Materiel Command, and others. She is currently an associated editor for Radiation Research, the International Journal of Radiation Biology, PLOS One, and Nanomedicine. She is Vice President of NCRP Program Area Committee 1, has served on organizational committees for several NCRP meetings, and has been involved in committees for several NCRP reports. She also served as Vice-President of the Radiation Research Society.

gayle e. woloschak



received a BS in nuclear engineering from Rensselaer Polytechnic Institute and an MS in environmental health sciences and a PhD in radiological health from New York University. For almost 40 y, he has been studying the metabolism, biokinetics, dosimetry, biological effects of internally deposited radionuclides, developing methods for removing radionuclides from the body (decorporation), and studying the mechanisms of deposition, clearance and retention of inhaled materials. Most of this research was performed at the Lovelace Respiratory Research Institute (LRRI) (formerly the Inhalation Toxicology Research Institute), where he worked for 23 y. From 2000 through 2007, he was team leader for internal dosimetry at the Los Alamos National Laboratory, assessing radiation doses for workers who were exposed to radionuclides associated with the nuclear weapons industry.

In 2007, he returned to LRRI as director of the Center for Countermeasures Against Radiation where he evaluated the efficacy of chemical compounds designed to decorporate radionuclides as well as drugs designed to ameliorate the effects of acute radiation syndrome from large external radiation doses in small and large animal models. He is a past president of the Health Physics Society, received its Distinguished Scientific Achievement Award in 2002, and has given several honorary lectures (Newell Stannard Memorial Lecture, 2006; G. William Morgan Lecture, HPS, 2009; inaugural Patricia W. Durbin Memorial Lecture, Lawrence Berkeley National Laboratory, 2010). He is a member of scientific committees of the International Commission on Radiological Protection, NCRP (a past board member), the International Agency for Research on Cancer, U.S. Environmental Protection Agency, and the U.S. National Academies of Science.

raymond a guilmette , Staff Consultant
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Last modified: August 2, 2018