EstimationoftheEffectiveDoseofRadiationWorkers:OptimizationBasedontheWeightPercentile

Keyhandokht Karimi Shahri1

(1.University of Birjand,Physics Department,School of Sciences,Birjand,Iran)

Abstract:Radiation workers might be exposed to polyenergetic photon radiation beams at different directions in their working environments.In this regard,their effective dose (E) should be accurately estimated using a two-dosimeter algorithm (TDA),based on the measurements of two thermoluminescent dosimeters (TLDs) or film badges that are mounted on the front and back of the body.However,considering different human anatomies,radiation workers may have a variety of weight percentiles.This work sought to find whether TDA obtained for the reference weight percentile (50th) can be used for higher weight percentiles (including;65th,75th,85th,and 95th).MCNPX was used to simulate different weight percentiles on the revised ORNL phantom by adding extra layers of muscle and adipose on the torso.Then front and back TLD responses were calculated for external beam photon energies of 40 keV to 10 MeV in different irradiation geometries.The results revealed that E value declines with increasing the weight percentile.In this study,three TDA were investigated consisting ofEest= 0.73Rf+ 0.53Rb(73/53),Eest= 0.55Rf+ 0.50Rb(55/50),andEest= 0.70Rf+ 0.30Rb(70/30).The ratio ofEest/Ewas calculated for each TDA in different energy bins and weight percentiles.Results obtained using the 55/50 and 70/30 showed higher underestimation for most of the energy bins,especially for PA and AP geometries.Compared to these two TDA,the 73/53 algorithm resulted in higher overestimation for RLAT and LLAT geometries for the same energy bins.Variation of the algorithms showed a similar trend for the studied weight percentiles.To conclude,results obtained by TDA for the 50% weight percentile are applicable for weight percentiles >50%.

Keywords:effective dose;two-dosimeter algorithm;external dosimetry;radiation personnel

Health Phys.119(3):273-279;2020

EffectofRadiationDoseRateonCirculatoryDiseaseMortalityamongNuclearWorkers:ReanalysisofHanfordData

Michiya Sasaki1,Shin’ichi Kudo2,Hiroshige Furuta2

(1.Radiation Safety Research Center,Nuclear Technology Research Laboratory,Central Research Institute of Electric Power Industry,2-11-1 Iwado kita,Komae-shi,Tokyo 201-8511,Japan;2.Institute of Radiation Epidemiology,Radiation Effects Association,1-9-16 Kajicho,Chiyoda-ku,Tokyo 101-0044,Japan)

Abstract:The excess relative risk (ERR) of mortality for circulatory disease among nuclear workers was reanalyzed by taking into consideration the annual dose as the dose rate using publicly available epidemiological data of the Hanford site dedicated to the cohort study of nuclear workers in the US,the UK,and Canada.Values of the dose rate (cut-points) were chosen at 2 mSv y-1intervals from 2 to 40 mSv y-1,and risk estimates were made for 32,988 workers,considering the doses accumulated below and above each cut-point to have different effects.Similarly to that in the previous study for cancer by Sasaki et al.,examinations of sensitivity analysis were also carried out for different risk models,lag periods,and impacts of adjusting the monitoring period to find the effect of the dose rate.As a result,emergence of a statistically significant difference betweenβL1,which is the ERR for the doses accumulated below the specified cut-point,andβH1,which is the ERR for that above the specified cut-point,was observed for cut-point of the dose rate of 4,6,34,36,and 38 mSv y-1.While statistically negative values were estimated forβL1(4 and 6 mSv y-1) and forβH1(34,36,and 38 mSv y-1),the overall relationship between the ERR and the cut-point of the dose rate was found to be similar to that obtained by the analysis of the mortality for all cancers excluding leukemia.

Keywords:dose,low;epidemiology;health effects;risk estimates

Health Phys.119(3):280-288;2020

AssessmentofEyeLensDoseReductionwhenUsingLateralLeadShieldsonthePatient’sHeadduringNeurointerventionalFluoroscopicProceduresandCone-beamComputedTomography(CBCT)Scans

Zhenyu Xiong1,2,Stephen Rudin2,Daniel R.Bednarek2

(1.Division of Medical Physics and Engineering,Department of Radiation Oncology,UT Southwestern Medical Center,Dallas,TX;2.Department of Radiology,The State University of New York at Buffalo,Buffalo,NY)

Abstract:The purpose of this study was to evaluate the effect of placing small lead shields on the temple region of the skull to reduce radiation dose to the lens of the eye during interventional fluoroscopically-guided procedures and cone-beam computed tomography (CBCT) scans of the head.EGSnrc Monte Carlo code was used to determine the eye lens dose reduction when using lateral lead shields for single X-ray projections,CBCT scans with different protocols,and interventional neuroradiology procedures with the Zubal computational head phantom.A clinical C-Arm system was used to take radiographic projections and CBCT scans of anthropomorphic head phantoms without and with lead patches,and the images were compared to assess the effect of the shields.For single lateral projections,a 0.1 (0.3)-mm-thick lead patch reduced the dose to the left-eye lens by 40% to 60% (55% to 80%) from 45° to 90° RAO and to the right-eye lens by around 30% (55%) from 70° to 90° RAO.For different CBCT protocols,the reduction of lens dose with a 0.3-mm-thick lead patch ranged from 20% to 53% at 110 kVp.For CBCT scans of the anthropomorphic phantom,the lead patch introduced streak artifacts that were mainly in the orbital regions but were insignificant in the brain region where most neurointerventional activity occurs.The dose to the patient’s eye lens can be reduced considerably by placing small lead shields over the temple region of the head without substantially compromising image quality in neuro-imaging procedures.

Keywords:diagnostic imaging;dose,organ;Monte Carlo;radiation dose

Health Phys.119(3):289-296;2020

EffectsofAmifostinePre-treatmentonMIRNA,LNCRNA,andMRNAProfilesintheHypothalamusofMiceExposedto60CoGammaRadiation

Baolei Tian,Hangjiang Fu,Bin Liu,Jie Zhu,Xiaofei Zheng,Changhui Ge1

(1.Department of Experimental Hematology and Biochemistry,Beijing Key Laboratory for Radiobiology,Beijing Institute of Radiation Medicine,Beijing,100850,China)

Abstract:There is increasing evidence that the expression of non-coding RNA and mRNA (messenger RNA) is significantly altered following high-dose ionizing radiation (IR),and their expression may play a critical role in cellular responses to IR.However,the role of non-coding RNA and mRNA in radiation protection,especially in the nervous system,remains unknown.In this study,microarray profiles were used to determine microRNA (miRNA),long non-coding RNA (lncRNA),and mRNA expression in the hypothalamus of mice that were pretreated with amifostine and subsequently exposed to high-dose IR.Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed.We found that fewer miRNAs,lncRNAs,and mRNAs were induced by amifostine pre-treatment in exposed mice,which exhibited antagonistic effects compared to IR,indicating that amifostine attenuated the IR-induced effects on RNA profiles.GO and KEGG pathway analyses showed changes in a variety of signaling pathways involved in inflammatory responses during radioprotection following amifostine pre-treatment in exposed mice.Taken together,our study revealed that amifostine treatment altered or attenuated miRNA,lncRNA,and mRNA expression in the hypothalamus of exposed mice.These data provide a resource to further elucidate the mechanisms underlying amifostine-mediated radioprotection in the hypothalamus.

Keywords:gamma radiation;health effects;radiation protection;radiation,ionizing

Health Phys.119(3):297-305;2020

PillarsofHospitalPreparednessinRadiationEmergencyManagement

Hossein Ghaedi1,Amir Ashkan Nasiripour1,Seyed Jamaledin Tabibi1,Majid Assadi2

(1.Department of Health Services Management,Science and Research Branch,Islamic Azad University,Tehran,Iran;2.The Persian Gulf Nuclear Medicine Research Center,Bushehr Universityof Medical Sciences,Bushehr,Iran)

Abstract:Human beings have always suffered and have incurred irreparable damages from different disasters.The most logical way to deal with disaster is to be comprehensively prepared.In line with this,the readiness of hospitals in the vicinity of nuclear centers is of great importance,as this could lead to reduced injuries and damage.In this study,we aimed to develop a model by which hospitals could effectively react to nuclear incidents.This is a comparative study using library studies,including examining existing patterns,recommended policies and instructions of WHO and IEAE,and articles and documents of selected countries that have models for radiation disaster management.The primary developed model was discussed in expert panels and,ultimately,with some modifications,was finalized.The findings of the research indicated that the most important factors in the success of crisis management are skill in predicting a crisis and having a preparation plan for necessary measures at the time of an incident.Different countries have developed various approaches toward radiation incident management that are mostly focused on human resources,medical equipment,and physical space.The model plan developed here includes a two-part foundation with seven pillars.Intra- and intersectorial arrangements are considered as the foundation,and the pillars are physical structure,medical equipment,human resources,process and instructions,intra- and intrasectorial coordination,information systems,and organizational structure.Having an appropriate model for coping with radiation incidents is pivotal for hospitals active in areas with nuclear centers.Undoubtedly,existence of an effective and comprehensive model could reduce the consequences of radiation crises.

Keywords:accidents,handling;accidents,nuclear;emergency preparedness;safety standards

Health Phys.119(3):306-314;2020

InhibitingGlycogenSynthaseKinase-3MitigatestheHematopoieticAcuteRadiationSyndromeinaSex-andStrain-dependentMannerinMice

Andrea R.Daniel1,Chang-Lung Lee1,2,Patrick Oh1,Lixia Luo1,Yan Ma1,David G.Kirsch1,3

(1.Department of Radiation Oncology；2.Department of Pathology；3.Department of Pharmacology &Cancer Biology,Duke University Medical Center,Durham,NC 27710)

Abstract:The Radiation and Nuclear Countermeasures Program at the National Institute of Allergy and Infectious Diseases (NIAID) mandated that medical countermeasures for treating Acute Radiation Syndrome (ARS) must have efficacy when administered at least 24 h after radiation exposure.At this time point,many cells within key target tissues,such as the hematopoietic system and the gastrointestinal (GI) tract,will already be dead.Therefore,drugs that promote the regeneration of surviving cells may improve outcomes.The serine/threonine kinase glycogen synthase kinase-3 (GSK-3) regulates stem and progenitor cell self-renewal and regeneration in the hematopoietic and GI compartments.We tested inhibition of GSK-3β by SB216763 24 h after total body irradiation (TBI) and sub-total body irradiation (SBI).Here,we show that subcutaneous administration of SB216763 promotes the regeneration of surviving hematopoietic stem/progenitor cells (HSPCs),including myeloid progenitor cells,and improves survival of C57Bl/6 male mice when administered 24 h after TBI.However,these results were not recapitulated in female C57Bl/6 animals,suggesting a sex difference in GSK-3β signaling in HSPCs.Subcutaneous administration of SB216763 in male mice stimulated activation of Sox2 transcription but failed to induce Sox2 transcription in female C57Bl/6 mice.Using TCF/lef-GFP reporter mice,we examined Wnt signaling in HSPCs of irradiated male and female mice treated with SB216763.GSK-3 inhibition elevated Wnt reporter activity in HSPCs isolated from male but not female mice.SB216763 did not mitigate hematopoietic ARS in males or females of a second strain of wild-type mice,C3H.In addition,administration of SB216763 did not mitigate hematopoietic ARS beyond the currently available standard approved therapy of ciprofloxacin and granulocyte-colony stimulating factor (G-CSF) in male C57Bl/6 mice.Further,SB216763 did not mitigate GI-ARS after SBI in C57Bl/6 male mice.The lack of efficacy in both sexes and multiple strains of mice indicate that SB216763 is not suitable for further drug development as a mitigator of ARS.Our studies demonstrate that activation of Wnt signaling in HSPCs promotes hematopoietic regeneration following radiation exposure,and targeting this pathway downstream of GSK-3β may mitigate ARS in a sex- and strain-independent manner.

Keywords:accidents,nuclear;exposure,radiation;health effects;modeling,biological factors

Health Phys.119(3):315-321;2020

OccupationalContaminationwithaHighlyEnrichedUraniumSolution

Ross A.Mullinax1,Bart O.Iddins2,Michael A.Alday2,David A.McLaughlin2

(1.US Department of the Navy;2.U.T.Battelle,Oak Ridge National Laboratory)

Abstract:This medical case report describes the first reported instance of occupational skin contamination with a uranyl nitrate solution containing highly enriched uranium.The report provides an overview of the unique medical treatment and management considerations in such a case.Internal dose assessment is covered in detail.The discussion covers key points regarding uranium characteristics,chemical and radiological damage to body tissues from HEU exposure,and resources available for assistance with a case of radiological contamination.This information adds to the limited medical literature on this topic and provides a valuable reference for medical personnel when dealing with this uncommon problem.

Keywords:contamination;health effects;occupational safety;uranium

Health Phys.119(3):322-326;2020

UraniumAerosolActivitySizeDistributionsataNuclearFuelFabricationPlant

Edvin Hansson1,2,H?kan B.L.Pettersson3,Mats Eriksson1,4

(1.Department of Medical and Health Sciences,Link?ping University,58183 Link?ping,Sweden;2.Westinghouse Electric Sweden AB,Br?nslegatan 1,72136 V?ster?s,Sweden;3.Department of Radiation Physics,and Department of Medical and Health Sciences,Link?ping University,58183 Link?ping,Sweden;4.Swedish Radiation Safety Authority,17116 Stockholm,Sweden)

Abstract:Inhalation of uranium aerosols is a concern in nuclear fuel fabrication.Determination of committed effective doses and lung equivalent doses following inhalation intake requires knowledge about aerosol characteristics;e.g.,the activity median aerodynamic diameter (AMAD).Cascade impactor sampling of uranium aerosols in the breathing zone of nuclear operators was carried out at a nuclear fuel fabrication plant producing uranium dioxide via ammonium uranyl carbonate.Complementary static sampling was carried out at key process steps.Uranium on impaction substrates was measured using gross alpha counting and alpha spectrometry.Activity size distributions were evaluated for both unimodal and bimodal distributions.When a unimodal distribution was assumed,the average AMAD in the operator breathing zone at the workshops was 12.9-19.3 μm,which is larger than found in previous studies.Certain sampling occasions showed variable isotope ratios (234U/238U) at different impactor stages,indicating more than one population of particles;i.e.,a multimodal activity size distribution.When a bimodal distribution (coarse and fine fraction) was assumed,75%-88% of the activity was associated with an AMAD of 15.2-18.9 μm (coarse fraction).Quantification of the AMAD of the fine fraction was associated with large uncertainties.Values of 1.7-7.1 μm were obtained.Static sampling at key process steps in the workshops showed AMADs of 4.9-17.2 μm,generally lower than obtained by breathing zone sampling,when a unimodal distribution was assumed.When a bimodal distribution was assumed,a smaller fraction of the activity was associated with the coarse fraction compared to breathing zone sampling.This might be due to impactor positioning during sampling and sedimentation of large particles.The average committed effective dose coefficient for breathing zone sampling and a bimodal distribution was 1.6-2.6 μSv Bq-1for234U when Type M/S absorption parameters were assumed (5.0 μSv Bq-1for an AMAD of 5 μm).The corresponding lung equivalent dose coefficient was 3.6-10.7 μSv Bq-1(29.9 μSv Bq-1for an AMAD of 5 μm).The predicted urinary excretion level 100 d after inhalation intake was found to be 13%-34% of that corresponding to an AMAD of 5 μm.Uranium aerosols generated at a nuclear fuel fabrication plant using ammonium uranyl carbonate route of conversion were associated with larger AMADs compared to previous work,especially when sampling of aerosols was carried out in the operator breathing zone.A bimodal activity size distribution can be used in calculations of committed effective doses and lung equivalent doses,but parameters associated with the fine fraction must be interpreted with care due to large uncertainties.

Keywords:aerosols;contamination,internal;lungs,human;nuclear workers

Health Phys.119(3):327-341;2020

AReviewofRadonEquilibriumFactorsinUndergroundMines,Caves,andThermalSpas

Jing Chen1,Naomi H.Harley2

(1.Radiation Protection Bureau,Health Canada,775 Brookfield Road,Ottawa K1A 1C1,Canada;2.New York University School of Medicine,1 Marine View Plaza,Hoboken,NJ)

Abstract:Radon equilibrium factorFeqis an important factor in radon progeny dose assessment.A review of published measurements ofFeqshows a range of values from 0.1 to 1.0 reported in studies from more than 26 countries measured in 173 underground mines,and 136 show caves,tourist mines,and thermal spas.The average values ofFeqare 0.38 in underground mines and 0.39 for show caves,tourist mines,and thermal spas.The wide range ofFeqin those special workplaces suggests that location-,environment-,and operation-specific values are more appropriate than a recommended average value in the calculation of lung bronchial dose.This is especially important in mines or other typically high radon exposure locations becauseFeqcan be used for recording an individual’s occupational radon exposure or dose.

Keywords:review paper;222Rn

Health Phys.119(3):342-350;2020

AcuteRadiation-inducedGI-ARSandH-ARSinaCanineModelofMixedNeutron/GammaRelativetoReferenceCo-60GammaRadiation:ARetrospectiveStudy

Thomas J.MacVittie1,William Jackson III2

(1.University of Maryland,School of Medicine,Department of Radiation Oncology,10 South Pine Street,MSTF 5-02,Baltimore,MD 21201;2.Statistician,Rockville,MD)

Abstract:Studies performed decades ago in the canine and nonhuman primate established the dose response relationships for the hematopoietic acute radiation syndrome in response to mixed neutron/gamma,X-radiation,and60Co gamma radiation.There were no published studies that determined the dose response relationships for the gastrointestinal acute radiation syndrome in response to either noted radiation quality.This analysis of a retrospective,unpublished study provided the dose response relationships in a canine model for the acute gastrointestinal syndrome relative to the acute hematopoietic syndrome due to mixed neutron/gamma radiation.Canines were exposed to total-body,steady state,bilateral,0.40 Gy min-1,mixed neutron/gamma (5.4∶1) radiation from a TRIGA reactor.The average neutron/gamma energy (MeV) was 0.85/0.9,and exposure was reported as midline tissue dose.Medical management was not administered.The mixed neutron/gamma exposure resulted in an estimatedLD50/6of 2.83 Gy [2.76,2.94] and LD50/30 of 2.16 Gy [2.01,2.24] for the GI- and H-ARS respectively.The mean survival times for decedents after mixed neutron/gamma exposure approximate to theLD50/6were 8.5 d,10.5 d,and 4 d for 2.75 Gy,2.80 Gy,3.00,and 3.12 Gy exposures,respectively.The mean survival times for decedents for mixed neutron/gamma exposure approximate to theLD50/30were 21.3 d and 15.6 d for 2.00 Gy and 2.25 Gy,respectively.Furthermore,the dose response relationships for the acute hematopoietic syndrome due to mixed neutron/gamma exposure (0.85/0.9 MeV;5.4:1) resulted in an estimated relative biological effectiveness of 1.2 as compared with reference60Co gamma radiation.

Keywords:dogs;neutrons;radiation damage;radiation effects

Health Phys.119(3):351-357;2020

TheShadowRule,theUVIndex,andthe5SStepsintheTropics

(1.Instituto de Estudos Avan?ados (IEAv),Trevo Cel Av José Alberto Albano do Amarante 1,Putim,S?o José dos Campos,CEP 12.228-001,SP,Brazil)

Abstract:Solar ultraviolet radiation (UVR) induces the production of vitamin D (VD),but it also causes erythema and skin cancer among other diseases.The amount of UVR to get benefit and avoid harm is unknown.Some principles were proposed to provide accessible information on how to avoid overexposure to the Sun.They are (1) the Shadow Rule (SR);(2) the UV Index (UVI);and (3) the Slip,Slop,Slap,Seek,Slide (5S) steps.This work discusses these principles in the tropics,considering measurements of solar UVR,total ozone column,and cloudiness.Indeed,the SR leads to overexposures.The UVI is adequate for cloudless skies,but it does not consider radiation enhancement events by clouds.“Seek shade” in the 5S steps should be more emphasized as it is both the most efficient step in terms of avoiding direct sun and the friendliest step toward the environment.Therefore,photoprotection attitudes in the tropics should focus on the UVI and the 5S steps in addition to considering both VD sufficiency and environmental outcomes.The SR is clearly inaccurate.

Keywords:health effects;public information;radiation,nonionizing;ultraviolet radiation

Health Phys.119(3):358-362;2020

TritiumAtomExchangeMayBeResponsibleforActivityDecreaseinPlasticLiquidScintillationVials

John Wang,Alexander Brandl1

(1.1618 Campus Delivery,Colorado State Univeristy,Fort Collins,CO 80523)

Abstract:Detection and measurement of low-energy beta particles is commonly achieved by liquid scintillation counting,in particular for low-level tritium samples.When samples are contained in plastic scintillation vials for long-term storage,the tritium activity in the vials has been found to decrease faster than expected from its natural radioactive decay.Different explanations for this observation have attributed some of these tritium activity losses to diffusion of the sample,degradation of the LSC cocktail,and the potential long-term changes in quenching effects of the LSC cocktail.An alternative explanation may also be that the tritium organically binds to the carbon chains in the plastic bottle through direct1H and3H atom exchange.A study was designed and performed to test this latter hypothesis of1H and3H atom exchange in plastic.Deionized water was introduced in a plastic vial that previously contained tritiated water to assess any increase in tritium activity from the reverse atom exchange between the vial material and the deionized water.A greater loss in activity concentration is observed in plastic vials compared to glass vials as a function of storage time for the tritiated water.Furthermore,the tritium activity concentration in the deionized water increased when storage occurred in plastic vials,an effect that is not observed for storage in glass vials.The study results indicate that hydrogen atom exchange may possibly take place in plastic vials.

Keywords:operational topics;detector,scintillation;instrumentation;tritium

Health Phys.119(3):375-380;2020

InhalationalExposureCausesRadioactiveMaterialUptakeforMultipleWorkers

Lara R.Paciello1,Julian J.Owoc II2

(1.Beaver Valley Power Station,Route 168 Shippingport;2.Private Company [Confidential],Wampum,PA 15077)

Abstract:Seven individuals were occupationally exposed to airborne radioactive material,which caused an intake of multiple isotopes and an uptake of60Co.Committed effective dose equivalents were calculated using ICRP Publication 30 methodology in accordance with US Regulation 10 CFR 20.Doses were in the range of 0.1-2.63 mSv for all individuals.Continued monitoring via whole body counting continues to detect internal contamination of60Co from this event at 321 d post intake.

Keywords:operational topics;60Co;bioassay;dosimetry,internal;inhalation

Health Phys.119(3):381-384;2020