Health Phys. Abstracts，Volume 120,Number 5

DeterminingAverageLinearDimensionandVolumeofKoreanLungsforLungPhantomConstruction

Sook Yang1, Jeongin Kim1, Seung Jin Choi1, Kyung Won Lee2

(1.Radiation Health Institute, 172, Dolma-ro, Bundang-gu, Seongnam-si, Gyeonggi-do, Republic of Korea;

2. Seoul National University Bundang Hospital, 173, Gumi-ro, Bundang-gu, Seongnam-si, Gyeonggi-do, Republic of Korea;

3. Radiation Health Institute, 172, Dolma-ro, Bundang-gu, Seongnam-si, Gyeonggi-do, Republic of Korea 13605;

4. Seoul National University, Bundang Hospital, 173, Gumi-ro, Bundang-gu, Seongnam-si, Gyeonggi-do, Republic of Korea, 13620)

Abstract:The purpose of this study was to determine the average size and volume of lungs and to simulate the morphology of internal organs for the development of a Korean adult lung phantom. The body-size data of 2,195 males and 2,293 females aged between 20 and 60 y were included to calculate the average physical dimensions. Two hundred datasets of computed tomography corresponding to the average physique range were collected to measure the average linear dimensions (the length of x, y, and z-axis) of lungs. One set of lung CT images was finally obtained and converted to three-dimensional (3D) format. To confirm the validity of the new lung model, physical lung phantoms were constructed using International Commission on Radiation Units and Measurements (ICRU) density and similar density to what was obtained from the human CT image and then compared with the Lawrence Livermore National Laboratory (LLNL) phantom. The mean size of the chest width and thickness was 31.8 ± 2.8 and 21.4 ± 1.9 cm for males and 28.0 ± 1.6 cm and 19.4 ± 2.0 cm for females, respectively. The standard deviation of the lung dimension in this group was ± 3.0 cm in length, ± 0.8 cm in width, and ± 2.27 cm in depth. The two modified lung phantoms showed highly accurate geometry and linear attenuation coefficient vs. those of the LLNL phantom. The difference in CT number was ± 2% HU for the LLNL phantom and ± 4% HU for the human CT image based on a CT examination conducted using the chest CT protocol. Moreover, both lungs weighed 734 g to 1,246 g, within the range of the reference value of the ICRU report. These results demonstrate that a new lung model based on average linear dimension measurement in a group with average physique simulated the features and physical properties of real human lungs and facilitated further studies for phantom construction.

Keywords: analysis, statistical; lungs, human; phantom; radiation protection

Health Phys. 120(5):487-494; 2021

AnalysisofEnvironmentalDatatoSupportQuantificationofHistoricalReleasesfromaFormerUraniumProcessingFacilityinApollo,Pennsylvania

H. Justin Mohler1, Arthur S. Rood2, Helen A. Grogan3, Emily A. Caffrey4, John E. Till5

(1.Bridger Scientific, Inc., 125 Jackpot Lane, Belgrade, MT 59714;

2. K-Spar, Inc., 4835 W Foxtrail Lane, Idaho Falls, ID 83402;

3. Cascade Scientific, Inc., 1678 NW Albany Avenue, Bend, OR 97703;

4. Radian Scientific, LLC, 806 Wells Ave. SE, Huntsville, AL 35801;

5. Risk Assessment Corporation, 417 Till Road, Neeses, SC 29107)

Abstract:This paper describes how environmental measurement data were used to help quantify the spatial impact and behavior of uranium released to the environment from a uranium manufacturing facility in Apollo, PA. The Apollo facility released enriched uranium to the environment while it operated between 1957 and 1983. Historical monitoring data generated by the site, along with other independent data sources, provided a long-term record documenting the presence and behavior of uranium in the local environment. This record of evidence, together with reconstructed estimates of facility releases, has been used to estimate environmental concentrations during facility operations and potential exposures to members of the public. Historical environmental measurement data were also used to confirm predictions of deposition and concentrations in air. The data are used here to derive atmospheric deposition velocities for the uranium emissions. Based on the spatial pattern of measurements and calculated deposition velocities around the facility, the released material contained larger particles that deposited close to the facility, and the released material remains largely in the surface layers of the soil, indicating limited downward mobility. Evidence of measurable impacts was determined to extend a relatively short distance (<500 m) from the facility. The soil data collected around Apollo are also compared to findings related to uranium mobility at another facility where uranium was released to the environment, and similar behavior was observed at both sites.

Keywords: environmental impact; environmental transport; soil; uranium

Health Phys. 120(5):495-509; 2021

RadiationSafetyforYttrium-90-polymerComposites(RadioGelTM)inTherapyofSolidTumors

Darrell R. Fisher1

(1.Department of Pharmaceutical Sciences, Washington State University, Richland, WA 99354)

Abstract:Yttrium-90 (90Y)-polymer composite (RadioGelTM) is a new cancer therapeutic agent for treating solid tumors by direct interstitial injection. The90Y-composite comprises insoluble, microscopic yttrium-phosphate particles carried by a sterile, injectable water-polymer (hydrogel) solution that can be placed directly by needle injection into solid tumors. The yttrium-90-RadioGelTMagent was designed to provide a safe, effective, localized, high-dose beta radiation for treating solid tumors. The properties of90Y-RadioGelTMalso make it a relatively safe agent for health care personnel who prepare, handle, and administer the material. The purpose of this work was to demonstrate and characterize radiation safety of the injectable90Y-RadioGelTMtherapeutic agent. Safety in the patient is defined by its ability to target precisely and remain confined within tumor tissue so that radiation doses are imparted to the tumor and not to normal organs and tissues. Radiation safety for health care personnel is defined by the low radiation doses received by persons who prepare and administer the agent. These safety features were demonstrated during experiments, first involving laboratory rabbits and second in cat and dog animal patients that were treated clinically for sarcoma tumors. This paper focuses mainly on the rabbit tissue biodistribution study; follow-on clinical application in cat and dog subjects confirmed the rabbit results. Implanted VX2 liver tumors in the hind limbs of 26 New Zealand White rabbits were treated using tracer amounts of either (a)90Y-RadioGelTMor (b)90Y-microparticles in phosphate-buffered saline (PBS) without the gel carrier. Tumor and margin injections were interstitial. Rabbits were euthanized at 48 h or 10 d following injection. Blood and tissues (tumor or tumor margins, liver, lymph nodes, rib bone, kidney, spleen) were collected for liquid scintillation counting using wet-ash procedures. Biodistribution was also analyzed at 10 d post-injection using micro-computed tomography. Thirteen cat and dog subjects were also treated clinically for sarcomas. Liquid scintillation counting at 48 h post-injection of tumors or margins with90Y-RadioGelTMshowed that significant radioactivity was measurable only at the site of administration and that radioactivity above detector background was not found in blood or peripheral organs and tissues. At 10 d post-injection, microCT showed that yttrium phosphate microparticles were confined to the injection site. Yttrium-90 remained where placed and did not migrate away in significant amounts from the injection site. Radiation doses were confined mainly to tumors and margin tissues. During preparation and administration, radiation doses to hands and body of study personnel were negligible. This work showed that90Y-RadioGelTMcan be safely prepared and administered and that radiation doses to cancer patients are confined to tumor and margin tissues rather than to critical normal organs and tissues.

Keywords: biokinetics; cancer; dose, internal; medical radiation

Health Phys. 120(5):510-516; 2021

DoseEstimationofLandfillDisposalofRemovedSoilGeneratedOutsideFukushimaPrefecture

Asako Shimada, Takuma Sawaguchi, Seiji Takeda1

(1. Nuclear Safety Research Center, Japan Atomic Energy Agency 2-4 Shirakara, Tokai-mura, Naka-gun, Ibaraki, Japan 319-1195)

Abstract:Dose estimation was conducted by assuming landfill disposal of removed soil generated outside the Fukushima Prefecture by each local town and in a lump sum. Because the radioactivity of removed soil is lower than that of specified waste that was generated at Fukushima Prefecture and the radioactivity concentration is 100,000 Bq kg-1or less, simple landfill covered with 30 cm of non-contaminated soil was used. The exposure doses of loading/unloading, transportation, and landfill workers and the public residing near the repository site were estimated. Furthermore, migration of cesium into groundwater because of precipitation and using the contaminated groundwater for drinking and agricultural water was evaluated, and exposure doses regarding farmers and the ingestion of agricultural products were estimated. It was confirmed that estimated exposure doses during landfill were less than 1 mSv y-1, and those for after landfill were 0.01 mSv y-1.

Keywords:134Cs;137Cs; accidents, power reactor; Fukushima Daiichi

Health Phys. 120(5):517-524; 2021

NonuniformExposuretotheCorneafromMillimeterWaves

Kenneth R. Foster1, Ilkka Laakso2, Steven Chalfin3

(1.Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19106;

2.Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland;

3.Ophthalmology Department, University of Texas Health Science Center, San Antonio, TX 78229)

Abstract:This study examines the nonuniform exposure to the cornea from incident millimeter waves at 94-100 GHz. Two previous studies measured temperature increases in the rhesus cornea exposed to brief (1-6 s) pulses of high-fluence millimeter waves (94 GHz), one of which also estimated thresholds for corneal damage (reported as ED50, the dose resulting in a visible lesion 50% of the time). Both studies noted large variations in the temperature increase across the surface of the cornea due to wave interference effects. This study examines this variability using high-resolution simulations of mm-wave absorption and temperature increase in the human cornea from exposures to plane wave energy at 100 GHz. Calculations are based on an earlier study. The simulations show that the peak temperature increases in the cornea from short exposures (up to 10 s) to high-intensity mm-wave pulses are 1.7-2.8 times the median increase depending on the polarization of the incident energy. A simple one-dimensional “baseline” model provides a good estimate of the median temperature increase in the cornea. Two different estimates are presented for the thresholds for producing thermal lesions, expressed in terms of the minimum fluence of incident 100 GHz pulses. The first estimate is based on thresholds for thermal damage from pulsed infrared energy, and the second is based on a thermal damage model. The mm-wave pulses presently considered far exceed current IEEE or ICNIRP exposure limits but may be produced by some nonlethal weapons systems. Interference effects due to wave reflections from structures in and near the eye result in highly localized variations in energy absorbed in the cornea and surrounding facial tissues and are important to consider in a hazard analysis for exposures to intense pulsed millimeter waves.

Keywords: radiation damage; radiation, non-ionizing; safety standards; radiofrequency radiation

Health Phys. 120(5):525-531; 2021

TemporalCharacterizationofTritiumSmearActivities

Adam J. Stavola, Adam G. Hartberger1

(1.Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, VA 23606)

Abstract:Tritium collection efficiency varies as a function of smear media. The use of porous smear materials leads to an increase in the measured tritium activity as a function of time when the measurement is performed with liquid scintillation counters. Operational inclusion of the efficiency differences and the time dependence of the tritium smear activity is necessary to preclude inadvertently releasing materials or areas. Thomas Jefferson National Laboratory Radiological Control Department identified a contaminated stainless steel containment vessel that previously housed a target containing more than 37 TBq of tritium. The item was systematically sectioned and surveyed to compare three smear types: water-wetted cotton swabs, water-wetted paper smears, and ethanol-wetted Styrofoam wipes (NUC-WipesTM). The total activity of each section was determined using repeated decontamination. The time dependence of the measured activity was also studied. The measured activity of both paper smears and cotton swabs showed significant time dependence. The cotton swabs also showed significantly reduced collection efficiency. Given the widespread use of both of these media in routine contamination surveys, site operational limits were derived using fitted curves for time dependence and average efficiency results. The use of these more restrictive limits allows for rapid measurement of tritium smears while ensuring regulatory compliance.

Keywords: contamination; decontamination; surface contamination; tritium

Health Phys. 120(5):532-540; 2021

IdentificationofFerroptosisBiomarkerinAHH-1LymphocytesAssociatedwithLowDoseRadiation

Jie Yin1,2,3, Nan Hu1, Lan Yi1,2,3, Weichao Zhao1, Xinjie Cheng1, Guoqing Li2,3, Nanyang Yang2,3, Guangyue Li1, Dexin Ding1

(1.Key Discipline Laboratory of National Defense for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang, Hunan 421001, People’s Republic of China;

2.College of Pharmacy and Biological Sciences, University of South China, Hengyang, Hunan 421001, People’s Republic of China;

3.Key Laboratory of Ecological Environment and Critical Human Diseases Prevention of Hunan Province Department of Education, University of South China, Hengyang, Hunan 421001, People’s Republic of China)

Abstract:The impact of long-term low-dose radiation on human health has always been a concern. Long-term low-dose gamma radiation causes cells continuous injury and causes chromosomal mutations to greatly increase the chance of cancer. Because it is significant to identify biomarkers for long-term low-dose gamma radiation, we investigate the influence of low dose rate on the gene expressions in the AHH-1 lymphocytes cell line (AHH-1 cells) for long-term irradiation. Different dose rates (7, 14, 26, 34, and 43 μGy h-1) of irradiation from gamma radiation in uranium tailings powder were used to irradiate AHH-1 lymphocytes. We used flow cytometry to test the apoptosis of AHH-1 lymphocytes at different dose rates and irradiation times (7-84 d). It was found that 14 μGy h-1is the most sensitive dose rate of AHH-1 lymphocyte irradiation. The 7-, 14-, and 21-d (2.4, 4.8, and 7.2 mGy) irradiation groups were sensitive, and the 84-d (28.8 mGy) irradiation group was insensitive to low dose gamma radiation. Microarray analysis was conducted on the significantly differentially expressed genes (p<0.05) in the 2.4, 4.8, 7.2, and 28.8 mGy irradiation groups. We found that TFRC1, SLC3A2, SLC39A8, FTH1, ACSL4, and GPX4 are significant genes with low-dose radiation and were constituents of the ferroptosis signaling pathway. In the range of 0-4.8 mGy radiation dose, the expressions of these genes were downregulated with increasing radiation dose, while in the range of 4.8-28.8 mGy, its expression increased with increasing radiation dose. RT-PCR and Western blot were used to detect the mRNA and protein expression of these genes. The results were consistent with those from microarray analysis. Our findings indicate that expression of the TFRC, SLC3A2, SLC39A, FTH1, ACSL4, and GPX4 genes is sensitive to low-dose radiation, and they are main members of the ferroptosis signaling pathway. Therefore, there is a very important connection between ferroptosis and low-dose radiation, which has become a hot topic in international research. These results can provide reference to the effect of ferroptosis on human health with low-dose radiation.

Keywords: accidents, nuclear; biological indicators; dose, low; health effects

Health Phys. 120(5):541-551; 2021

MeasurementofNaturalRadionuclidesandAssessmentofRadiationHazardinCoalfromPartsofChina

Wenhong Li, Shuo Wang, Baolu Yang, Fei Tuo1

(1.Key Laboratory of Radiological Protection and Nuclear Emergency, China CDC, National Institute for Radiological Protection, Chinese Centre for Disease Control and Prevention, Beijing 100088, China)

Abstract:To study the content of radionuclides in coal and to assess its associated radiological impact on the environment for potential radiological risk assessment, a total of 40 coal samples were collected from various mining areas in eight provinces of China. The specific activities of226Ra,232Th,40K,210Pb, and238U were measured in all samples using an HPGe gamma-ray spectrometer, and results were compared with available data from other similar studies. The results reveal that the radium equivalent activity was 74.20 Bq kg-1, external hazard index was 0.20, internal hazard index was 0.27, representative gamma index was 0.52, and indoor and outdoor annual effective dose rates were 0.16 nSv y-1and 0.04 nSv y-1, respectively. Absorbed gamma dose rate in air was 32.87 nGy h-1. In general, these values are lower than the respective threshold limits recommended by UNSCEAR, and the radiation risk to the public is extremely small.

Keywords: coal; fly ash; radionuclide; radioactivity, background

Health Phys. 120(5):552-558; 2021

ComparisonofNeutronOrganandEffectiveDoseCoefficientsforPIMALStylizedPhantomsinBentPosturesinCranialandCaudalIrradiationGeometries

Sruthi Sivabhaskar1, Alexander Perry2, Shaheen Dewji2

(1.Department of Physics, Texas A&M University, College Station, TX 77843;

2. Department of Nuclear Engineering, Texas A&M University, College Station, TX 77843)

Abstract:Radiation dose estimations in the human body are performed using computational reference phantoms, which are anatomical representations of the human body. In previous studies, dose reconstructions have been performed focusing primarily on phantoms in an upright posture, which limits the accuracy of the dose estimations for postures observed in realistic work settings. In this work, the International Commission on Radiological Protection (ICRP) Publication 103 recommendations for monoenergetic neutron plane sources directed downward from above the head (cranial) and upward from below the feet (caudal) for adult female and male reference phantoms were used to calculate organ absorbed and effective dose coefficients. The Phantom with Moving Arms and Legs (PIMAL) and the Monte Carlo N-Particle (MCNP) radiation transport code were used to compute organ-absorbed dose and effective dose coefficients for the upright, half-bent (45°), and full-bent (90°) phantom postures. The doses calculated for each of the articulated positions were compared to those calculated for the upright posture by computing the ratios of the coefficients (45°/upright and 90°/upright). These ratios were used to assess the effectiveness of upright phantoms in providing a comparable estimate when conducting dose estimations and dose reconstructions for articulated positions. This work compiling neutron cranial and caudal posture-specific dose coefficients completes the series of dose coefficients computed for posture-specific ICRP Publication 116 irradiation geometries for monoenergetic photons and neutrons, in addition to cranial and caudal monoenergetic photons. Results reported demonstrated that organ-absorbed dose coefficients for most of the organs in the CRA and CAU irradiation geometries were significantly higher for the bent phantoms than for the upright phantom. Since the upright phantom underestimates the organ-absorbed dose, this demonstrates the impact of posture while performing dose calculations. Organ doses reported in past neutron dose coefficient data were found to omit effects from neutron resonances at energies of 0.435, 1.0, and 3.21 MeV from16O in tissue. Reported data notes as high as 60% underestimation for neutron organ-absorbed doses, specifically at the neutron resonance energy region omitted by smoothing. Ongoing studies are examining the effect of resonances on reported neutron organ-absorbed dose coefficients in ICRP 116 geometries.

Keywords: effective dose; Monte Carlo; neutron dosimetry; phantom, mathematical

Health Phys. 120(5):559-572; 2021

RadonKineticsinaBasementSpaceMeasuredwithDifferentDevices

Long Kiu Chung, Nathan P. Piersma, Kimberlee J. Kearfott1

(1.Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Abor, Michigan, 48109-2104)

Abstract:Although indoor monitoring of radon and benchmarking of radon measurement devices remain important research topics, few intercomparisons of active radon measurement devices have been performed under realistic conditions, let alone dynamic ones enabling comparison of their transient behavior. Five different radon monitors were therefore placed in a poorly ventilated basement space under three different conditions: 24 h under a steady, elevated radon level, 24 h with fans turned on to produce a radon washout transient, and 9 d with fans turned off for a radon buildup transient. Resulting radon concentrations varied between ～200 and ～2,000 Bq m-3. Accuracy of the devices were evaluated using root-mean-square error, and ventilation data were fit to first order linear compartmental models. To more accurately model behaviors such as cyclic diurnal variations, the source term corresponding to entry of radon from soil into the basement was considered to be non-constant, as it is likely to vary drastically with both the indoor-outdoor pressure differential and soil concentration variations. The improved radon washout model fit very well with the measurements. Despite a wide variety in list prices, all devices performed similarly during transients and at different radon concentrations.

Keywords: operational topics; radon; radon monitors; ventilation

Health Phys. 120(5):582-588; 2021