Health Phys. Abstracts，Volume 123,Number 2

RadiobiologyofSelectRadionuclidesinHanfordSiteTankWaste

Antone L.Brooks1, David Hoel2, Wayne M.Glines3

(1.Research Professor Emeritus, Washington State University Tri-Cities, Richland, WA;2.Medical University of South Carolina, 36 South Battery, Charleston, SC 29401;3.US Department of Energy(retired), Richland, WA)

Abstract:There are several important radionuclides involved in the “clean-up” or environmental isolation of nuclear waste contained in US Department of Energy Hanford Site underground waste tanks that drive many of the decisions associated with this activity.To make proper human health risk analyses and ensure that the most appropriate decisions are made, it is important to understand the radiation biology and the human health risk associated with these radionuclides.This manuscript provides some basic radiological science, in particular radiation biology, for some of these radionuclides, i.e.,3H,90Sr,137Cs,99Tc,129I, and the alpha emitters239, 240Pu,233,234,235,238U, and241Am.These radionuclides were selected based on their designation as “constituents of potential concern,” historical significance, or potential impact on human health risk.In addition to the radiobiology of these select radionuclides, this manuscript provides brief discussions of the estimated cost of planned management of Hanford tank waste and a comparison with releases into the Techa River from activities associated with the Mayak Production Association.A set of summary conclusions of the potential human health risks associated with these radionuclides is given.

Keywords: health effects; radiobiology; waste management; waste storage

Health Phys.123(2):99-115; 2022

MedicalCountermeasureRequirementstoMeetNASA’sSpaceRadiationPermissibleExposureLimitsforaMarsMissionScenario

Charles M.Werneth1, Tony C.Slaba1, Janice L.Huff1, Zarana S.Patel2,3, Lisa C.Simonsen1

(1.NASA Langley Research Center, Hampton, VA;2.KBR Inc., Houston, TX;3.NASA Johnson Space Center, Houston, TX)

Abstract:The space radiation environment consists of a complex mixture of ionizing particles that pose significant health risks to crew members.NASA currently requires that an astronaut’s career Risk of Exposure Induced Death(REID)for cancer mortality should not exceed 3% at the upper 95% confidence level.This career radiation limit is likely to be exceeded for even the shortest round-trip mission scenario to Mars.As such, NASA has begun to pursue more vigorously approaches to directly reduce radiation risks, despite the large uncertainties associated with such projections.A recent study considered cohort studies of aspirin and warfarin as possible medical countermeasures(MCMs)acting to reduce background cancer mortality rates used in astronaut risk projections.It was shown that such MCMs can reduce the REID for specific tissues in restricted time intervals over which the drugs were administered; however, the cumulative effect on total lifetime REID was minimal.As an extension, the present work addresses more general MCM requirements that would be needed to meet current NASA radiation limits for a Mars mission scenario.A sensitivity analysis is performed within the major components of the NASA cancer risk model that would likely be modified by MCM interventions.This includes the background cancer incidence and mortality rates, epidemiologically based hazard rates derived from acute terrestrial exposures, and radiation quality factors used to translate terrestrial exposures to space radiation.Relationships between possible MCMs and each of these components are discussed.Results from this study provide important information regarding MCM requirements needed to meet NASA limits for planned Mars missions.Insight into the types of countermeasures expected to yield greatest reductions in crew risk is also gained.

Keywords: physics; particle; quality factor; radiation; radiation risk

Health Phys.123(2):116-127; 2022

ExternalRadiationDosetoOwnersofCaninesTreatedwith(117mSn)RadiosynoviorthesisforOsteoarthritis

Chad A.Smith1, Rebecca A.Krimins2

(1.FX Masse, Gloucester, MA;2.Johns Hopkins University, Baltimore, MD)

Abstract:A novel device in the veterinary market uses a colloid containing radioactive117mSn to treat osteoarthritis in the synovial joints of canines.The technique of injecting a radioisotope to restore synovia is referred to as radiosynoviorthesis.The outpatient canine procedure uses a maximum administration of 222 MBq of117mSn injected into one or more joints.Due to the 13.91 d half-life and 158.6 keV gamma output of117mSn, abiding by the annual public dose limit of 1 mSv is of primary regulatory concern.The therapy protocol starts with a pre-screening questionnaire to establish owner and animal behavior patterns.The questionnaire is used to determine the duration of written time and distance limitations post therapy.In this study, external radiation doses to owners were measured by providing optically stimulated luminescent dosimeters(OSLD)for up to 30 d post-treatment of the pet.Twelve owners were measured over various time frames at two licensed locations independent of each other.In one location, the average(OSLD)measured 0.029 mSv over a 14 d wear period.In the second location, the average(OSLD)measured 0.057 mSv over a 30 d wear period; both values were well below the recommended annual public dose.The overall average extrapolated external radiation dose was estimated at 0.092 mSv, while the maximum dose estimate was 0.25 mSv.The(OSLD)results and extrapolated owner doses provide reasonable assurance that the public dose limits will be met.

Keywords: dogs; dose; health effects; radiation; medical

Health Phys.123(2):128-132; 2022

ImplicationsofRecentEpidemiologicalStudiesforCompensationofVeteransExposedtoPlutonium

Jan Beyea

(Senior Scientist, Emeritus, Consulting in the Public Interest, 53 Clinton Street, Lambertville, NJ 08530,jbeyea@cipi.com)

Abstract:The objective of this paper is to compare post-2007 epidemiological results for plutonium workers to risk predicted by the software program NIOSH-IREP(IREP for short), which is used to determine the lowest dose for a US veteran to obtain cancer compensation.IREP output and methodology were used to predict excess relative risk per Gy(ERRGy-1)for lung cancer at the 99thcredibility percentile, which is used for compensation decisions.Also estimated were relative biological effectiveness factors(RBE)predicted for workers using IREP methodology.IREP predictions were compared to results for Mayak and Sellafield plutonium workers, separately and pooled.Indications that IREP might underpredict 99th-percentile lung cancer plutonium risk came from(1)comparison of worker RBEs and(2)from comparison of Sellafield results separately.When Sellafield and Mayak data were pooled,ERRGy-1comparisons at the 99thpercentile roughly matched epidemiological data with regression dose range restricted to < 0.05 Gy, the most relevant region to veterans, but overpredicted for the full dose range.When four plausible distributions for lung cancer risk, including both new and old data, were combined using illustrative weighting factors, compensation cutoff dose for lung cancer matched current IREP values unless regression results below 0.05 were chosen for Sellafield, producing a two-fold reduction.A 1997 claim of a dose threshold in lung cancer dose response was not confirmed in later literature.The benefit of the doubt is given to claimants when the science is unclear.The challenge for NIOSH-IREP custodians is dealing with the Sellafield results, which might best match US claimants.

Keywords: epidemiology; plutonium; relative biological effectiveness; risk estimates

Health Phys.123(2):133-153; 2022

Lutetium-177RadiopharmeceuticalTherapyExtravasationLessonsLearned

Kendall Berry, MSPH, RSO, Jessica Kendrick, MS

(Fox Chase Cancer Center, 333 Cottman Avenue, R347, Philadelphia, PA 19111Kendall.Berry@FCCC.edu)

Abstract:Lutetium-177(177Lu)dotatate has been offered at Fox Chase Cancer Center since 2017 as part of a clinical trial and then in 2018 as a commercially available cancer therapy, and we thought we were prepared for most177Lu issues by the fall of 2020.A single phone call identified that the Radiation Safety Department had not been prepared to address extravasations.Fortunately for the patient and Radiation Safety, the177Lu therapies are administered by an infusion nurse and Fox Chase Cancer Center has a robust infusion center.The expertise of our infusion center team helped to quickly identify specific mitigation efforts to employ.A team of radiation safety and diagnostic medical physicists worked together to estimate a tissue dose.Research was also started with the aim of identifying therapeutic177Lu extravasations as early as possible.The lessons we learned and plans for future early identification of177Lu dotatate extravasations are the basis of this paper.

Keywords: operational topics; health effects; medical radiation; radiopharmaceuticals

Health Phys.123(2):160-164; 2022

IDAC-Bio,ASoftwareforInternalDosimetryBasedontheNewICRPBiokineticModelsandSpecificAbsorbedFractions

Martin Andersson1,2, Richard W.Leggett3, Keith Eckerman3, Anja Almén2, S?ren Mattsson2

(1.Department of Radiation Physics, Sahlgrenska Cancer Center, University of Gothenburg, Sweden;2.Medical Radiation Physics Malm?, ITM, Lund University, SE-205 02 Malm?, Sweden;3.Center for Radiation Protection Knowledge, Oak Ridge National Laboratory, Oak Ridge, TN)

Abstract:Radiation dosimetry is central to virtually all radiation safety applications, optimization, and research.It relates to various individuals and population groups and to miscellaneous exposure situations—including planned, existing, and emergency situations.The International Commission on Radiological Protection(ICRP)has developed a new computational framework for internal dose estimations.Important components are more detailed and improved anatomical models and more realistic biokinetic models than before.The ICRP is currently producing new organ dose and effective dose coefficients for occupational intakes of radionuclides(OIR)and environmental intakes of radionuclides(EIR), which supersede the earlier dose coefficients in Publication 68 and the Publication 72 series, respectively.However, the ICRP only publishes dose coefficients for a single acute intake of a radionuclide and for an integration period of 50 years for intake by adults and to age 70 years for intakes by pre-adults.The new software, IDAC-Bio, performs committed absorbed dose and effective dose calculations for a selectable intake scenario, e.g., for a continuous intake or an intake during x hours per day and y days per week, and for any selected integration time.The software uses the primary data and models of the ICRP biokinetic models and numerically solves the biokinetic model and calculates the absorbed doses to organs and tissues in the ICRP reference human phantoms.The software calculates absorbed dose using the nuclear decay data in ICRP publication 107.IDAC-Bio is a further development and an important addition to the internal dosimetry program IDAC-Dose2.1.The results generated by the software were validated against published ICRP dose coefficients.The potential of the software is illustrated by dose calculations for a nuclear power plant worker who had been exposed to varying levels of60Co and who had undergone repeated whole-body measurements, and for a hypothetical member of the public subject to future releases of148Gd from neutron spallation in tungsten at the European Spallation Source.

Keywords: dosimetry; internal; International Commission on Radiological Protection; medical exposure; occupational safety

Health Phys.123(2):165-172; 2022