Organ dose reconstruction for the radiation epidemiological study of Korean radiation workers: the first dose evaluation for the Korean Radiation Worker Study (KRWS).

The Korea Institute of Radiological and Medical Sciences has started a radiation epidemiological study, titled "Korean Radiation Worker Study," to evaluate the health effects of occupational exposure to radiation. As a part of this study, we investigated the methodologies and results of reconstructing organ-specific absorbed doses based on personal dose equivalent, (10), reported from 1984 to 2019 for 20,605 Korean radiation workers. For the organ dose reconstruction, representative exposure scenarios (i.

Experience and performance of In Vivo Monitoring Laboratory of NIRP in 2017 thyroid measurement intercomparison.

Determination of the I activity in the thyroid of exposed people or workers is one of the major concerns that needs to be addressed following a nuclear or radiological emergency. International intercomparison exercises on bioassay measurements are one of the effective methods to improve the capability and quality of internal dose assessment. In 2017, Working Group 1 (Internal Dosimetry) of the Asian Radiation Dosimetry Group (ARADOS) organized an intercomparison exercise on the thyroid measurement, aiming at enhancing and coordinating the radiation dosimetry capabilities of Asian countries.

Uncertainty quantification of bioassay functions for the internal dosimetry of radioiodine.

Bioassay functions, which are provided by the International Commission on Radiological Protection, are used to estimate the intake activity of radionuclides; however, they include considerable uncertainties in terms of the internal dosimetry for a particular individual. During a practical internal dose assessment, the uncertainty in the bioassay function is generally not introduced because of the difficulty in quantification. Therefore, to clarify the existence of uncertainty in the bioassay function and provide dosimetrists with an insight into this uncertainty, this study attempted to quantify the uncertainty in the thyroid retention function used for radioiodine exposure.

Evaluation of performance characteristics of portal monitor for radiation emergency.

For evaluating the counting efficiency of a portal monitor, we use aCs radiation point source (1 μCi) to subsequently establish it effective measurable area. Through simulation, we estimate the appropriate distance from potentially contaminated individuals in the scanning queue to the monitoring individual. When this distance is over 10 m, the counting efficiency was below 0.

PRACTICAL METHODS FOR INTERNAL DOSE ASSESSMENT FOR RADIOIODINE INTAKE AFTER THYROID BLOCKING: CLASSIFICATION OF DEGREE OF BLOCKAGE AND DETERMINATION OF INSENSITIVE MEASUREMENT POINT.

Iodine thyroid blocking (ITB) suppresses the uptake of iodine to the thyroid and reduces internal doses after radioiodine intake; however, its disturbance of thyroid biokinetics causes considerable uncertainty in the use of dosimetric data intended for assessment of unblocked normal thyroid. To more accurately assess internal dose after ITB, practical dosimetry methods were proposed that consider the ITB effect in a dosimetric manner. A method using the ratio of urine excretion to thyroid retention activity was proposed to retrospectively determine individual-specific ITB levels; bioassay functions and dose coefficients corresponding to ITB levels were calculated separately using the latest biokinetic model and fundamental data.

Internal Dose Assessment after 131I-Iodide Misadministration in a Patient With Incompletely Blocked Thyroid Uptake: Personalized Internal Dose Assessment by Estimating Individual-Specific Biokinetics.

In July 2017, a medical accident occurred in South Korea, in which I-iodide solution was misadministered to the wrong patient. Although the International Commission on Radiological Protection provided internal dose coefficients for iodine for blocked thyroid, they were not reliable enough for determining the dose to the patient (whose thyroid uptake was incompletely blocked) due to a discrepancy in biokinetics. Therefore, a personalized dose assessment was performed to derive the individual-specific dose coefficients for the patient.

Counting Efficiencies Determined by Monte Carlo Methods for In Vivo Measurement of 131I Activity in Thyroid.

The counting efficiencies obtained using a physical neck phantom are typically used in the measurement of I activity in the thyroid. It is well known, however, that the geometrical discrepancies between the physical neck phantom and the anatomy of the subject can significantly influence the counting efficiencies. Thus, it is necessary to consider the anatomical characteristics of individuals if we need to accurately determine the activity of I in the thyroid.

Health effects of exposure to radon: implications of the radon bed mattress incident in Korea.

Radon is a naturally occurring radioactive material formed by the slow decay of uranium and thorium found in the earth's crust or construction materials. Internal exposure to radon accounts for about half of the natural background radiation dose to which humans are exposed annually. Radon is a carcinogen and is the second leading cause of lung cancer following smoking.

RAPID MONITORING OF INTERNAL CONTAMINATION USING A MOBILE RADIOBIOASSAY LABORATORY FOLLOWING RADIATION EMERGENCIES.

In any radiation emergency, it may be necessary to monitor large numbers of people for internal contamination resulting from inhalation/ingestion of radionuclides released from the accident. The National Radiation Emergency Medical Center of the Korea Institute of Radiological and Medical Sciences constructed a mobile radiobioassay laboratory for rapid field-based monitoring of internal contamination. The main features of the mobile laboratory were designed and the results of performance were tested for rapid monitoring in this paper.

Screening Criteria for the General Public in Radiation Emergencies From Liquid Scintillation Urinalysis.

Gross alpha/beta screening of urine samples was performed to evaluate internal contamination and dose assessment. Data on background radioactivity concentration were extracted by analyzing the urine samples of non-contaminated individuals who had visited a radiation effect medical clinic since 2012. Screening criteria were studied and established for radiation emergencies based on these results.

Measurement and Simulation of the Counting Efficiency of a Whole-body Counter Using a BOMAB Phantom Inserted with Rod Sources Containing Mixed Radionuclides.

The examination of internal contamination is important for providing an adequate medical response during a radiological emergency. A whole-body counting system can assess gamma-emitting radionuclides in a human body when monitoring internal contamination. It is necessary to calibrate whole-body counting systems by using a calibration phantom, such as a Bottle Manikin Absorption phantom, to properly assess internal contamination.

Development of a minipig physical phantom from CT data.

Quantification of pathological progression of radiation-induced injury is essential in development of treatment methods, and a proper animal model is necessary for relevant radiological and medical studies. A minipig is a current animal model selected because of its similarities to humans in anatomy and pathology. In the present study, a minipig physical phantom was developed using computed tomography (CT) data.

Estimation of counting efficiencies of a portable NaI detector using Monte Carlo simulation for thyroid measurement following nuclear accidents.

Radioiodine can be released in nuclear accidents and can cause internal contamination of the thyroid gland in members of the public. For population monitoring in radiation emergencies, measurement of counting efficiency is very important to accurately determine thyroid activity. Here, we estimate the counting efficiencies of a portable NaI detector using Monte Carlo simulations.

Rapid Analysis of 239,238Pu, 241Am, and 90Sr for Nasal Smear Samples in Radiation Emergency and Evaluation of Intake Retention Fraction.

The efficiency of the nasal smear method was reviewed to perform a method of sample collection, analysis and initial dose estimation. The screening method of alpha-emitting radionuclides using chemical separation and alpha spectrometry was also studied. To rapidly conduct the appropriate response to victims, special monitoring for Pu, Am, and Sr using sequential analysis was established, and the method was successfully validated through participation in an international inter-comparison program.

Monitoring and Dose Assessment for Children Following a Radiation Emergency Part I: Reference Values for In Vitro Bioassay.

Following a radiation emergency, children may be internally contaminated by the radionuclide(s) involved. Timely assessment of the contamination informs the need for medical treatment for those persons who had significant intakes and reassures those whose intakes are not a medical concern. In vitro bioassay reference values for children of all ICRP age groups are derived for 30 contamination scenario/radionuclide combinations involving 13 radionuclides.

Effective dose evaluation of NORM-added consumer products using Monte Carlo simulations and the ICRP computational human phantoms.

The aim of this study is to evaluate the potential hazard of naturally occurring radioactive material (NORM) added consumer products. Using the Monte Carlo method, the radioactive products were simulated with ICRP reference phantom and the organ doses were calculated with the usage scenario. Finally, the annual effective doses were evaluated as lower than the public dose limit of 1mSv y(-1) for 44 products.

Estimates of Radiation Doses and Cancer Risk from Food Intake in Korea.

The aim of this study was to estimate internal radiation doses and lifetime cancer risk from food ingestion. Radiation doses from food intake were calculated using the Korea National Health and Nutrition Examination Survey and the measured radioactivity of (134)Cs, (137)Cs, and (131)I from the Ministry of Food and Drug Safety in Korea. Total number of measured data was 8,496 (3,643 for agricultural products, 644 for livestock products, 43 for milk products, 3,193 for marine products, and 973 for processed food).

Feasibility study for the assessment of the exposed dose with TENORM added in consumer products.

Consumer products including naturally occurring radioactive material have been distributed widely in human life. The potential hazard of the excessively added technically enhanced naturally occurring radioactive material (TENORM) in consumer products should be assessed. The aim of this study is to evaluate the organ equivalent dose and the annual effective dose with the usage of the TENORM added in paints.

Retrospective biodosimetry using translocation frequency in a stable cell of occupationally exposed to ionizing radiation.

Two cases of hematological malignancies were reported in an industrial radiography company over a year, which were reasonably suspected of being consequences of prolonged exposure to ionizing radiation because of the higher incidence than expected in the general population. We analyzed chromosomal aberrations in the peripheral blood lymphocytes from the other workers who had been working under similar circumstances as the patients in the company. Among the subjects tested, 10 workers who belonged to the highest band were followed up periodically for 1.

Effective dose conversion coefficients for health care provider exposed to pediatric and adult victims in radiological dispersal device incident.

After an incident of radiological dispersal devices (RDD), health care providers will be exposed to the contaminated patients in the extended medical treatments. Assessment of potential radiation dose to the health care providers will be crucial to minimize their health risk. In this study, we compiled a set of conversion coefficients (mSv MBq(-1) s(-1)) to readily estimate the effective dose from the time-integrated activity for the health care providers while they deal with internally contaminated patients at different ages.

Screening of alpha- and beta-emitting radionuclides using liquid scintillation counting and monitoring procedures in radiation emergencies.

Urine gross alpha and beta activity analysis was conducted, and an internal contamination screening method was adopted to monitor visitors to Japan after the Fukushima accident. In particular, spot urine samples were used to evaluate internal contamination for 16 mo, and a total of 90 people participated in gross alpha and beta emitter screening. An ultra-low-background liquid scintillation counter was used for measurement, and optimal pulse shape analysis values were determined by measuring alpha- and beta-emitting certified reference materials.

32P measurement and dose conversion factor evaluation of activated human hair by criticality accident.

In order to conduct dose assessment of victims in criticality accidents, a method of fast neutron capture-activated (32)P measurement of hair in which samples are treated by a chemical and analytical procedure that takes 9 h and measurement is conducted by liquid scintillation counting is presented. To validate this measurement method, hair samples spiked with a (32)P reference source were measured and the results analysed and the optimal sample mass and detection efficiency were determined. To verify the correlation between (32)P-specific activity and absorbed dose for spectra with two neutron mean energies, samples collected from three normal individuals were irradiated at various neutron energies and irradiation times using the MC50 Cyclotron of the Korea Institute of Radiological and Medical Sciences.

Tritium analysis of urine samples from the general Korean public.

The tritium concentrations of urine samples and the effective dose of the general Korean public were evaluated. To achieve accurate HTO analysis of urine samples, we established the optimal conditions for measuring the HTO content of urine samples. Urine samples from 50 Koreans who do not work at a nuclear facility were analyzed on the basis of the results.

Evaluation of sodium activation distribution in the PMMA water phantom after fast neutron irradiation.

(24)Na produced by the neutron activation of stable sodium in the body is commonly used to assess neutron doses after criticality accidents. However, the (24)Na distribution is not uniform owing to the interaction with the human body. In this study, we experimentally evaluated the (24)Na distribution in a PMMA water phantom and 60 polyethylene vials.

Radioactive contamination monitoring for the Korean public following Fukushima nuclear accident.

On March 11, 2011, as a result of the Great East Japan Earthquake, severe damage to the Fukushima nuclear power plant caused the release of radioactive materials. We conducted radioactive contamination monitoring for Korean residents in Japan and Korean travelers to East Japan after the accident. More than 800 members of the Korean public were surveyed for personal monitoring.