Health Phys.Abstracts，Volume 119,Number 2

EstimationofExternalContaminationandExposureRatesDuetoFissionProductRelease

S.A.Dewji1,2, K.Bales2,3, E.Asano1,2,4, K.Veinot5, K.Eckerman6, S.Hart2, L.Finklea7, A.Ansari7

(1.Department of Nuclear Engineering, Texas A & M University, College Station, TX;2.Oak Ridge National Laboratory, Oak Ridge, TN;3.Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX;4.Nuclear Engineering Department, University of Tennessee, Knoxville, Knoxville, TN;5.Y-12 National Security Complex, Oak Ridge, TN;6.Easterly Scientific, Knoxville, TN;7.Centers for Disease Control and Prevention, Atlanta, GA)

Abstract:In the event of a radiological incident, the release of fission products into the surrounding environment and the ensuing external contamination present a challenge for triage assessment by emergency response personnel.Reference exposure rate and skin dose rate calibration data for emergency response personnel are currently lacking for cases where receptors are externally contaminated with fission products.Simulations were conducted to compute reference exposure rate coefficients and skin dose rate coefficients from photon-emitting fission products of radiological concern.To accomplish this task, simplified mathematical skin phantoms were created using surface area and height specifications from International Commission on Radiological Protection Publication 89.Simulations were conducted using Monte Carlo radiation transport code using newborn, 1-y-old, 5-y-old, 10-y-old, 15-y-old, and adult phantoms for 22 photon-emitting radionuclides.Exposure rate coefficient data were employed in a case study simulating the radionuclide inventory for a 17 × 17 Westinghouse pressurized water reactor, following three burn-up cycles at 14,600 MWd per metric ton of uranium.The decay times following the final cycle represent the relative activity fractions over a period of 0.5-30 d.The resulting data can be used as calibration standards for triage efforts in emergency response protocols.

Keywords: emergency planning; exposure, radiation; fission products; skin dose

Health Phys.119(2):163-175; 2020

OrganDosesfromChestRadiographsinTuberculosisPatientsinCanadaandTheirUncertaintiesinPeriodsfrom1930to1969

David C.Kocher1, A.Iulian Apostoaei1, Brian A.Thomas1, David Borrego2, Choonsik Lee2, Lydia B.Zablotska3

(1.Oak Ridge Center for Risk Analysis, Inc., Oak Ridge, TN;2.Radiation Epidemiology Branch, National Cancer Institute, Bethesda, MD;3.Department of Epidemiology and Biostatistics, School of Medicine, University of California, San Francisco, San Francisco, CA)

Abstract:This paper describes a study to estimate absorbed doses to various organs from film-based chest radiographs and their uncertainties in the periods 1930 to 1948, 1949 to 1955, and 1956 to 1969.Estimated organ doses will be used in new analyses of risks of cancer and other diseases in tuberculosis patients in Canada who had chest fluoroscopic and radiographic examinations in those periods.In this paper, doses to lungs, female breast, active bone marrow, and heart from a single chest radiograph in adults and children of ages 1, 5, 10, and 15 y in the Canadian cohort and their uncertainties are estimated using(1)data on the tube voltage(kV), total filtration(mm Al), tube-current exposure-time product(mA s), and tube output(mR s〗-1)in each period;(2)assumptions about patient orientation, distance from the source to the skin of a patient, and film size; and(3)new calculations of sex-and age-specific organ dose conversion coefficients(organ doses per dose in air at skin entrance).Variations in estimated doses to each organ across the three periods are less than 20% in adults and up to about 30% at younger ages.Uncertainties in estimated organ doses are about a factor of 2 to 3 in adults and up to a factor of 4 at younger ages and are due mainly to uncertainties in the tube voltage and tube-current exposure-time product.

Keywords: dose, organ; radiation, medical; X rays; X-ray machines

Health Phys.119(2):176-191; 2020

Neuroman:VoxelPhantomsfromSurfaceModelsof300HeadStructuresIncluding12PairsofCranialNerves

Jin Seo Park1

(1.Department of Anatomy, Dongguk University School of Medicine, Republic of Korea)

Abstract:For a precise simulation of electromagnetic radiation effects, voxel phantoms require detailed structures to approximate humans.The phantoms currently used still do not have sophisticated structures.This paper presents voxel and surface models of 300 head structures with cranial nerves and reports on a technique for voxel reconstruction of the cranial nerves having very thin and small structures.In real-color sectioned images of the head(voxel size: 0.1 mm), 300 structures were segmented using Photoshop.A surface reconstruction was performed automatically on Mimics.Voxel conversion was run on Voxel Studio.The abnormal shapes of the voxel models were found and classified into three types: thin cord, thin layers, and thin parts in the structures.The abnormal voxel models were amended using extended, filled, and manual voxelization methods devised for this study.Surface models in STL format and as PDF files of the 300 head structures were produced.The STL format has good scalability, so it can be used in most three-dimensional surface model software.The PDF file is very user friendly for students and researchers who want to learn the head anatomy.Voxel models of 300 head structures were produced(TXT format), and their voxel quantity and weight were measured.A voxel model is difficult to handle, and the surface model cannot use the radiation simulation.Consequently, the best method for making precise phantoms is one in which the flaws of the voxel and surface models complement each other, as in the present study.

Keywords: electromagnetic fields; human organs; medical imaging; phantom

Health Phys.119(2):192-205; 2020

Revisiting35and94GHzMillimeterWaveExposuretotheNon-HumanPrimateEye

James E.Parker1, Charles W.Beason1, Stephen P.Sturgeon2, William B.Voorhees2, Samuel S.Johnson2, Kaitlin S.Nelson2, Leland R.Johnson2, Jeffrey N.Whitmore2

(1.General Dynamics Information Technology, JBSA Fort Sam Houston, TX 78234;2.Air Force Research Laboratory, 711th Human Performance Wing,Airman Systems Directorate, Bioeffects Division, Radio Frequency Bioeffects Branch, JBSA Fort Sam Houston, TX 78234.)

Abstract:A previous study reported thermal effects resulting from millimeter wave exposures at 35 and 94 GHz on non-human primates, specifically rhesus monkeys’(Macacamulatta)corneas, but the data exhibited large variations in the observed temperatures and uncertainties in the millimeter wave dosimetry.By incorporating improvements in models and dosimetry, a non-human primate experiment was conducted involving corneal exposures that agreed well with a three-layer, one-dimensional, thermodynamic model to predict the expected surface temperature rise.The new data indicated that the originally reported safety margins for eye exposures were underestimated by 41 ± 20% over the power densities explored.As a result, the expected minimal visible lesion thresholds should be raised to 10.6 ± 1.5 and 7.1 ± 1.0 J cm-2at 35 and 94 GHz, respectively, provided that the power density is less than 6 W cm-2for subjects that are unable to blink.If the blink reflex was active, a power density threshold of 20 W cm-2could be used to protect the eye, although the eyelid could be burned if the exposure was long enough.

Keywords: health effects; microwaves; modeling, dose assessment; radiation, non-ionizing

Health Phys.119(2):206-215; 2020

ARadonBackground-subtractionAlgorithmforElectronicPersonalDosimeters

R.Fabian, J.Bell, A.Brandl1

(1.Colorado State University, Fort Collins, CO)

Abstract:Many first responders are outfitted with electronic personal dosimeters to recognize and be alerted to radiological hazards during their response operations.These dosimeters provide invaluable measurement data for force protection, allowing the first responder to assess a response situation and take protective measures for themselves and other individuals involved based on instrument readings of dose rate or cumulative dose.However, capabilities of common electronic personal dosimeters to identify and distinguish various contributions to the instrument reading, in particular from natural radiological sources, are rather limited.An algorithm has been developed for two-channel electronic personal dosimeters that quantifies the signal contribution from radon progeny and allows for background subtraction from radon and radon progeny in the instrument reading.This algorithm will be particularly useful in operational scenarios where first responders may be subject to rapidly changing levels of natural background radiation, which could mimic the presence of anthropogenic sources of ionizing radiation.

Keywords: algorithm; radiation, background; radioactivity, natural; radon progeny

Health Phys.119(2):216-221; 2020

UncertaintiesinRadiationDosesforaCase-controlStudyofThyroidCanceramongPersonsExposedinChildhoodto131IfromChernobylFallout

Vladimir Drozdovitch1, Ausrele Kesminiene2, Monika Moissonnier2, Ilya Veyalkin3, Evgenia Ostroumova2

(1.Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, 9609 Medical Center Drive, Bethesda, MD 20892;2.International Agency for Research on Cancer, Lyon, France; 3.Republican Research Center for Radiation Medicine and Human Ecology, Gomel, Belarus)

Abstract:Uncertainties in thyroid doses due to131I intake were evaluated for 2,239 subjects in a case-control study of thyroid cancer following exposure to Chernobyl fallout during childhood and adolescence carried out in contaminated regions of Belarus and Russia.Using new methodological developments that became available recently, a Monte Carlo simulation procedure was applied to calculate 1,000 alternative vectors of thyroid doses due to131I intake for the study population of 2,239 subjects accounting for sources of shared and unshared errors.An overall arithmetic mean of the stochastic thyroid doses in the study was estimated to be 0.43 Gy and median dose of 0.16 Gy.The arithmetic mean and median of deterministic doses estimated previously for 1,615 of 2,239 study subjects were 0.48 Gy and 0.20 Gy, respectively.The geometric standard deviation of individual stochastic doses varied from 1.59 to 3.61 with an arithmetic mean of 1.94 and a geometric mean of 1.89 over all subjects of the study.These multiple sets of thyroid doses were used to update radiation-related thyroid cancer risks in the study population exposed to131I after the Chernobyl accident.

Keywords:131I; dosimetry; Chernobyl; thyroid

Health Phys.119(2):222-235; 2020

IEEECommitteeonManandRadiation—COMARTechnicalInformationStatement:HealthandSafetyIssuesConcerningExposureoftheGeneralPublictoElectromagneticEnergyfrom5GWirelessCommunicationsNetworks

J.T.Bushberg, C.K.Chou, K.R.Foster, R.Kavet, D.P.Maxson, R.A.Tell, M.C.Ziskin1

(1.Committee on Man and Radiation(COMAR), IEEE Engineering in Medicine and Biology Society)

Abstract:This COMAR Technical Information Statement(TIS)addresses health and safety issues concerning exposure of the general public to radiofrequency(RF)fields from 5G wireless communications networks, the expansion of which started on a large scale in 2018 to 2019.5G technology can transmit much greater amounts of data at much higher speeds for a vastly expanded array of applications compared with preceding 2-4G systems; this is due, in part, to using the greater bandwidth available at much higher frequencies than those used by most existing networks.Although the 5G engineering standard may be deployed for operating networks currently using frequencies extending from 100 s to 1,000 s of MHz, it can also operate in the 10s of GHz where the wavelengths are 10 mm or less, the so-called millimeter wave(MMW)band.Until now, such fields were found in a limited number of applications(e.g., airport scanners, automotive collision avoidance systems, perimeter surveillance radar), but the rapid expansion of 5G will produce a more ubiquitous presence of MMW in the environment.While some 5G signals will originate from small antennas placed on existing base stations, most will be deployed with some key differences relative to typical transmissions from 2-4G base stations.Because MMW do not penetrate foliage and building materials as well as signals at lower frequencies, the networks will require “densification,” the installation of many lower power transmitters(often called “small cells” located mainly on buildings and utility poles)to provide for effective indoor coverage.Also, “beamforming” antennas on some 5G systems will transmit one or more signals directed to individual users as they move about, thus limiting exposures to non-users.In this paper, COMAR notes the following perspectives to address concerns expressed about possible health effects of RF field exposure from 5G technology.First, unlike lower frequency fields, MMW do not penetrate beyond the outer skin layers and thus do not expose inner tissues to MMW.Second, current research indicates that overall levels of exposure to RF are unlikely to be significantly altered by 5G, and exposure will continue to originate mostly from the “uplink” signals from one’s own device(as they do now).Third, exposure levels in publicly accessible spaces will remain well below exposure limits established by international guideline and standard setting organizations, including ICNIRP and IEEE.Finally, so long as exposures remain below established guidelines, the research results to date do not support a determination that adverse health effects are associated with RF exposures, including those from 5G systems.While it is acknowledged that the scientific literature on MMW biological effect research is more limited than that for lower frequencies, we also note that it is of mixed quality and stress that future research should use appropriate precautions to enhance validity.The authorship of this paper includes a physician/biologist, epidemiologist, engineers, and physical scientists working voluntarily and collaboratively on a consensus basis.

Keywords: microwaves; radiation, low-level; radiation, non-ionizing; safety standards

Health Phys.119(2):236-246; 2020

DesignandCharacterizationofanExtremely-Sensitive,Large-VolumeGamma-RaySpectrometerforEnvironmentalSamples

James M.Seekamp1, Jordan D.Noey1, Emily H.Kwapis1, Long Kiu Chung1, Nasser A.Shubayr2, Travis Smith1, David J.Trimas1, Kimberlee J.Kearfott1

(1.Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109-2104;2.Diagnostic Radiology Department, Faculty of Applied Medical Sciences, Jazan University, Almaarfah Rd.Jazan, Saudi Arabia, P.O.Box: 114 Jazan, KSA, 45142)

Abstract:A large volume gamma spectrometer was designed and constructed to analyze foodstuffs and environmental samples having low radionuclide concentrations.This system uses eight 11-cm × 42.5-cm × 5.5-cm NaI(Tl)detectors, chosen due to their relatively high sensitivity and availability and arranged in an octagonal configuration.The sensitive volume of the system is ～28 cm in diameter and ～42 cm deep.Shielding consists of an 86-cm × 86-cm square, 64-cm-tall lead brick enclosure with 18-cm-thick lead walls lined by 0.3-cm-thick copper plates.An aluminum top was machined to suspend the detectors within this shield.The shielding reduces background counts by 72% at 100 keV and 42% at 1,000 keV.The positional variability in sensitivity of the well was determined by both simulation and experiment.A 2.1-L volume of nearly uniform sensitivity, varying less than 10%, exists in the well’s center.Energy resolutions of 14.6% and 7.8% were measured for241Am and137Cs, respectively.Energy resolution shows a 0.2% variation for both241Am and137Cs as a function of position within all regions of the well’s central sensitive volume.Dead time was also determined to be less than 35% for all sources measured in the system, the largest of which had an activity of 1,760 kBq.Simulated results for various source geometries show higher counts for smaller samples, especially at lower energies due to less attenuation of low energy photons.Minimum detectable activities were determined for all source energies used, less than 5.1 Bq kg-1for reasonable background and sample counting times.

Keywords: operational topics; contamination, environmental; radiation, gamma; spectroscopy, gamma

Health Phys.119(2):252-260; 2020

CompromiseofPersonalProtectiveClothingfromLiquidExposure

Scott O.Schwahn1, Nathaniel D.Foster2

(1.Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831-2008;2.Brookhaven National Laboratory, PO Box 5000, Upton, NY 11973-5000)

Abstract:Introduction: Following critiques of multiple personal contamination events from entries into the Oak Ridge National Laboratory’s Spallation Neutron Source Transfer Bay, it was considered that the most likely causes for contamination were personal protective clothing doffing errors or moisture(sweat)allowing contamination to wick through the protective clothing.Radiological protection staff looked more closely, however, at the specific area of the clothing where contamination was highest; under enhanced lighting and photochromic manipulation, there appeared to have been some type of moisture in the area.Recognizing the possibility that moisture may have allowed for migration of contamination through the clothing, further experiments were undertaken to determine under which conditions this transport might have occurred.Objective: The objective for this work was to identify the susceptibility of different types of personal protective clothing to various liquids encountered in the workplace.Method: Several tests were performed to determine if perspiration had enabled migration of contamination and to identify what other liquids might have affected contamination transport.Two layers of personal protective clothing were subjected to static conditions and dynamic conditions to include active rubbing of the materials while wet.Food dye added to each of the liquids tested enabled visual indications of liquid breakthrough.Additional tests were conducted to see if solid contamination could be transported through the materials along with the liquids.Results: All but one type of non-rubberized personal protective clothing in use at Oak Ridge National Laboratory were permanently compromised to some extent by the solvents used for decontamination.Conclusion: It was determined that most common cleaning agents immediately and permanently destroyed the hydrophobic nature of several of the tested protective clothing materials, potentially allowing for radioactive contamination to penetrate through the material to the worker.Work around wet surfaces or performing wet decontamination will only be performed in protective clothing known to prevent transport of the wetting agent.

Keywords: contamination, external; decontamination; operational topics; surface contamination

Health Phys.119(2):261-265; 2020