Whole-body Counting Research Articles

ON THE METHODOLOGY OF PASSPORT DOSES CALCULATION FOR UKRAINIAN SETTLEMENTS RADIOACTIVELY CONTAMINATED DUE TO THE CHORNOBYL NPP ACCIDENT.

scientific substantiation of the new methodology for estimation of passport doses of the settlementswhich belong to Zone of Unconditional (obligatory) Resettlement, or 2nd zone and Zone of Granted VoluntaryResettlement, or 3rd zone in the framework of dosimetric passportization in accordance with the legislation ofUkraine. 37 years after the accident, radioactive contamination of the environment has significantly decreased. However, it is still necessary to carry out ecological and dosimetric monitoring and apply countermeasures in certain territories of Ukraine affected by the accident at the Chornobyl Nuclear Power Plant: restriction of the consumption of locally produced milk, forest products, etc. The methodology, which was since 1996 used to estimate the passport doses of Ukrainian settlements, no longer corresponds to the current level of scientific knowledge about radioactive contamination of environment. The new methods of passport doses calculating presented in the work involves the use of a model whose parameters are determined by the types, quality and completeness of radio-ecological and dosimetric monitoring carried out on the radioactively contaminated territories in 1986-2013. The methodology takes into account the specific of radioactive contamination of each settlement. The passport dose of external exposure is reconstructed only from 137Cs radionuclide, because the contributions of other Chornobyl radionuclides influence the radiation dose only in the first years after the accident. The passport dose of internal exposure is formed as a result of the consumption of 137Cs contaminated food products. It is calculated depending on the availability in the settlement in the current year of the results of measurements of the 137Cs radionuclide activity incorporated in the human body using a whole body counter (WBC) and the activity of 137Cs in the private milk. At the same time, priority is given precisely to the results of WBC measurements of 137Cs. A new methodology (Methodology-2023) for passport doses calculation of Ukrainian settlements was substantiated. A comparison of passport doses based on the results of radioecological and dosimetric monitoring in 2011 calculated by Methodology-2023 and passport doses calculated by Methodology-96 was made.Passport doses calculated by Methodology-2023 increased by 40 % on average compared to doses calculated by Methodology-96. At the same time, passport doses of internal radiation calculated by the new methodologyincreased by 1.5 times, and passport doses of external radiation increased by 1.7 times. The passport dose of 2011, calculated by Methodology-2023, exceeds the legally established limit of 1 mSv in 71 settlements, most of which are located in Korostenkyi raion of Zhytomyr Oblast.

Radioactive contamination in feral dogs in the Chernobyl exclusion zone: Population body-burden survey and implications for human radiation exposure.

This report describes a two-year effort to survey the internal 137Cs and external β-emitter contamination present in the feral dog population near the Chernobyl nuclear power plant (ChNPP) site, and to understand the potential for human radiation exposure from this contamination. This work was performed as an integral part of the radiation safety and control procedures of an animal welfare oriented trap-neuter-release (TNR) program. The measurement program focused on external contamination surveys using handheld β-sensitive probes, and internal contamination studies using a simple whole-body counter. Internal 137Cs burden was measured non-invasively during post-surgical observation and recovery. External β contamination surveys performed during intake showed that 21/288 animals had significant, removable external contamination, though not enough to pose a large hazard for incidental contact. Measurements with the whole-body counter indicated internal 137Cs body burdens ranging from undetectable (minimum detection level ∼100 Bq/kg in 2017, ∼30 Bq/kg in 2018) to approximately 30,000 Bq/kg. A total of 33 animals had 137Cs body-burdens above 1 kBq/kg, though none posed an external exposure hazard. The large variation in the 137Cs concentration in these animals is not well-understood, could be due to prey selection, access to human food scraps, or extended residence in highly contaminated areas. The small minority of animals with external contamination may pose a contamination risk allowing exposures in excess of regulatory standards.

Дозы облучения населения Беларуси вследствие аварии на Чернобыльской атомной электростанции на 2021-2025 гг.

In accordance with the Laws of the Republic of Belarus «On the social protection of citizens affected by the accident at the Chernobyl NPP» dated January 6, 2009 and «On the legal regime of territories exposed to radioactive contamination due to the accident at the Chernobyl NPP» dated May 26, 2012, the value of the average annual effective dose of exposure to residents is one of the indicators of the radiation situation in settlements contaminated with radionuclides as a result of the Chernobyl accident. The objective: to update the method for assessing the exposure doses to the population in the situation of existing exposure after the Chernobyl accident and, on its basis, to assess the average annual effective exposure dose to residents of settlements of the Republic of Belarus due to the Chernobyl accident for the period 2021-2025. The method for estimating the average annual effective doses due to external and internal irradiation to residents of radioactively contaminated settlements of the Republic of Belarus has been improved taking into account international recommendations in the field of radiation protection, changes in the radiation situation in the long-time period after the Chernobyl accident and the new data on individual dosimetry of internal exposure to the population based on the results of whole-body counter (WBC) measurements. An assessment of the average annual effective exposure doses to the population of the Republic of Belarus residing in the territory of radioactive contamination was carried out, and based on its results, the Catalog of average annual effective exposure doses to residents of 2193 settlements for the period 2021-2025 was compiled. According to the compiled Catalog of average annual effective exposure doses to residents of settlements located on the territory of radioactive contamination of the Republic of Belarus, in 29 settlements out of 2193, the total effective exposure dose can exceed 1 mSv/year, in addition, it is about 1 mSv/year in 5 settlements. In none of the settlements, the average annual effective radiation dose can exceed 5 mSv/year. Valid for the period 2021-2025 Catalog of average annual effective exposure doses to the residents of settlements located on the territory of radioactive contamination of the Republic of Belarus, along with data on the density of contamination of the territories of the Republic of Belarus with long-lived radionuclides, was used to compile the List of settlements and objects located in the zones of radioactive contamination, and to adopt a Resolution of the Council of Ministers of the Republic Belarus on designation of settlements to the corresponding zones of radioactive contamination.

The association between upper gastrointestinal endoscopic findings and internal radiation exposure in residents living in areas affected by the Chernobyl nuclear accident.

Many people living around the Chernobyl Nuclear Power Plant (CNPP) have been exposed to 137Cs for several decades after the CNPP accident. Although half-life of 137Cs is about 30 years, some wild forest foodstuffs are contaminated by 137Cs even now. We pointed out in a previous report that low-dose internal radiation has been occasionally detected in people's body. Moreover, some doctors in local hospitals have claimed that internal exposure from contaminated foodstuffs may affect the digestive organs and possibly cause gastrointestinal (GI) diseases. Thus, we attempt to assess whether internal radiation exposure affects digestive organs or not, and the possible factors that influence digestive organs. Overall, 1,612 residents were assessed for internal 137Cs concentration using Whole-Body Counter and their digestive organs were screened with upper GI endoscopy from 2016-2018 in the Zhytomyr region, Ukraine. All participants answered to the questionnaire including their background, intake of wild forest foodstuff, intake frequency, smoking habits, and alcohol consumption. We checked the number of upper GI endoscopic diagnosis per person to assess the extent of damage to the upper digestive organs. Next, we statistically analyzed associations between this number and age, sex, level of internal exposure dose, alcohol consumption, wild forest foodstuff intake, and smoking. Consequently, we revealed that the number of GI diagnosis is significantly increased by factors such as sex, intake of wild forest foodstuff, and alcohol consumption. However, the average level of internal exposure of 137Cs and smoking did not relate to the number of GI diagnosis. Thus, the results of multiple regression revealed that alcohol consumption is independently related to the number of GI diagnosis that is most likely accompanied by the intake of wild forest foodstuff. In conclusion, the low-dose internal exposure may not affect the digestive organs of residents living around CNPP.

Determination of counting efficiency considering the biodistribution of 131I activity in the whole-body counting measurement

Whole-body counters are widely used to assess internal contamination after a nuclear accident. However, it is difficult to determine radioiodine activity due to limitations in conventional calibration phantoms. Inhaled or ingested radioiodine is heterogeneously distributed in the human body, necessitating time-dependent biodistribution for the assessment of the internal contamination caused by the radioiodine intake. This study aims at calculating counting efficiencies considering the biodistribution of 131I in whole-body counting measurement. Monte Carlo simulations with computational human phantoms were performed to calculate the whole-body counting efficiency for a realistic radioiodine distribution after its intake. The biodistributions of 131I for different age groups were computed based on biokinetic models and applied to age- and gender-specific computational phantoms to estimate counting efficiency. After calculating the whole-body counting efficiencies, the efficiency correction factors were derived as the ratio of the counting efficiencies obtained by considering a heterogeneous biodistribution of 131I over time to those obtained using the BOMAB phantom assuming a homogeneous distribution. Based on the correction factors, the internal contamination caused by 131I can be assessed using whole-body counters. These correction factors can minimize the influence of the biodistribution of 131I in whole-body counting measurement and improve the accuracy of internal dose assessment.

Monte Carlo simulations of vehicle-mounted whole-body NaI(Tl) counter

During a nuclear emergency, an internal exposure detection device with on-site and rapid measurements should be developed to assess the level of internal exposure of people in radioactively contaminated areas. Based on MCNP simulations, this work designed a shielding structure of a NaI(Tl) type vehicle-mounted whole-body counter (VM-WBC) and it has good shielding performance against the background radiation. The mass of the shielding structure was less than 800 kg, and the minimum detectable activity (MDA) of 60Co and 137Cs obtained by simulation for a 10 min measurement was less than 50 Bq. And we also study its counting efficiency calibration by simulating radiation computing phantoms with Chinese and American reference physiological characteristics. Equations that fit counting efficiency, body build index, and photon energy were also developed. The relative efficiency deviation between the equation and the MCNP simulation was less than 5%.

Lower Non-Heme Iron Absorption in Healthy Females from Single Meals with Texturized Fava Bean Protein Compared to Beef and Cod Protein Meals: Two Single-Blinded Randomized Trials.

Meat analogs based on plant protein extracts are rising in popularity as meat consumption declines. A dietary shift away from meat, which has a high iron bioavailability, may have a negative effect on the amount of iron absorbed from the diet. Iron absorption from legumes cultivated in regions not suitable for soy production, such as fava bean, has not yet been explored. The aim of this study was to evaluate non-heme iron absorption from a meal with texturized fava bean protein compared to beef and cod protein meals. The study included two single-blinded iron isotope trials in healthy Swedish women of the ages 18–45 years, each of whom served as their own control. The participants were served matched test meals containing beef and fava bean protein (Study 1) or cod and fava bean protein (Study 2) with radiolabeled non-heme iron 55Fe and 59Fe. The absorption of non-heme iron from test meals was measured by whole-body counting and erythrocyte incorporation. The absorption of non-heme iron, measured as erythrocyte incorporation ratio, from beef protein meal was 4.2 times higher compared to texturized fava bean meal, and absorption from cod protein meal was 2.7 times higher compared to the fava bean meal. The adjusted non-heme iron absorption, normalized to a 40% reference dose uptake, was 9.2% for cod protein meal, 21.7% for beef protein meal, and 4.2% for texturized fava bean meal. A fava bean protein meal has markedly lower iron bioavailability in healthy females compared with a meal of beef or cod protein. Therefore, a dietary shift from meat and fish protein to fava bean protein may increase the risk of iron deficiency.

Production of sealed rod sources made from epoxy resin for the Saint-Petersburg brick phantom for the calibration of whole-body counters

Rod sources are a common tool for the calibration of whole-body counters in combination with the Saint-Petersburg brick phantom. Here, a method for the production of such sources in ordinary radiochemical laboratories is presented. The rod sources consist of a tubular capsule of rigid polyvinyl chloride with a radioactive filling of epoxy resin. The method allows the production of rod sources at material costs of about 1 € per rod source and of ten rod sources by one person per day. Quality-assurance measurements were performed regarding the spatial distribution of the activity within the rod sources and the distribution of the activity throughout a set of sources. The relative double standard deviation of the activities of five different segments of single rod sources was 7.1%. The relative double standard deviation within a set of 90 rod sources was 2.8% after those 11% of sources with the greatest deviation from the arithmetic mean were discarded. Tests according to ISO 2919 to certify the rod sources as sealed sources of Class 2 of this standard were successfully conducted. The bending test proved to be the most critical test for the rod sources; the sources were broken by a mass of 12–14 kg, which is only slightly more than the stipulated mass of 10.2 kg. The presented method allows for a cost- and labour-effective production of sealed radioactive rod sources and thus facilitates the application of the Saint-Petersburg brick phantom for calibrations and interlaboratory comparisons of whole-body counters.

Doses from external irradiation and ingestion of 134Cs, 137Cs and 90Sr of the population of Belarus accumulated over 35years after the Chernobyl accident.

This study considers the exposure of the population of the most contaminated Gomel and Mogilev Oblasts in Belarus to prolonged sources of irradiation resulting from the Chernobyl accident. Dose reconstruction methods were developed and applied in this study to estimate the red bone-marrow doses (RBMs) from (i) external irradiation from gamma-emitting radionuclides deposited on the ground and (ii) 134Cs, 137Cs and 90Sr ingestion with locally produced foodstuffs. The mean population-weighted RBM doses accumulated during 35years after the Chernobyl accident were 12 and 5.7mGy for adult residents in Gomel and Mogilev Oblasts, respectively, while doses for youngest age groups were 20-40% lower. The highest mean area-specific RBM doses for adults accumulated in 1986-2021 were 63, 56 and 46mGy in Narovlya, Vetka and Korma raions in Gomel Oblast, respectively. For most areas, external irradiation was the predominant pathway of exposure (60-70% from the total dose), except for areas with an extremely high aggregated 137Cs soil to cow's milk transfer coefficient (≥ 5.0Bq L-1 per kBq m-2), where the contribution of 134Cs and 137Cs ingestion to the total RBM dose was more than 70%. The contribution of 90Sr intake to the total RBM dose did not exceed 4% for adults and 10% for newborns in most raion in Gomel and Mogilev Oblasts. The validity of the doses estimated in this study was assessed by comparison with doses obtained from measurements by thermoluminescence dosimeters and whole-body counters done in 1987-2015. The methodology developed in this study can be used to calculate doses to target organs other than RBM such as thyroid and breast doses. The age-dependent and population-weighted doses estimated in this study are useful for ecological epidemiological studies, for projection of radiation risk, and for justification of analytical epidemiological studies in populations exposed to Chernobyl fallout.

Performance testing of a FastScan whole body counter using an artificial neural network

In Korea, all nuclear power plants (NPPs) participate in annual performance tests including in vivo measurements using the FastScan, a stand type whole body counter (WBC), manufactured by Canberra. In 2018, all Korean NPPs satisfied the testing criterion, the root mean square error (RMSE) ≤ 0.25, for the whole body configuration, but three NPPs which participated in an additional lung configuration test in the fission and activation product category did not meet the criterion. Due to the low resolution of the FastScan NaI(Tl) detectors, the conventional peak analysis (PA) method of the FastScan did not show sufficient performance to meet the criterion in the presence of interfering radioisotopes (RIs), 134Cs and 137Cs. In this study, we developed an artificial neural network (ANN) to improve the performance of the FastScan in the lung configuration. All of the RMSE values derived by the ANN satisfied the criterion, even though the photopeaks of 134Cs and 137Cs interfered with those of the analytes or the analyte photopeaks were located in a low-energy region below 300 keV. Since the ANN performed better than the PA method, it would be expected to be a promising approach to improve the accuracy and precision of in vivo FastScan measurement for the lung configuration.

Effective population monitoring for determination of the thyroidal radioiodine content of the public following a nuclear accident in Japan

After a nuclear accident, population monitoring is necessary to determine the radiation exposure levels of the affected population. One of the monitoring components is direct thyroid measurements to assess the internal thyroid dose (mainly from 131I with a relatively short physical half-life: 8.02 days). These measurements are particularly important for young children but were not adequately performed after the 2011 Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. Herein we propose a feasible and robust method to obtain as much reliable human data as possible for the dose reconstructions following a nuclear accident. The method employs three types of measurements: simplified, additional, and detailed measurements. The simplified measurements are performed using conventional NaI(Tl) survey meters to quickly triage heavily exposed individuals. The additional measurements are conducted using mobile whole-body counters to detect cesium (Cs; with longer retention in the body) as a tracer of 131I. And the detailed measurements are taken using spectrometric devices; they provide the most reliable data and are used to confirm the other measurements. We also discussed the target subjects and the monitoring period based on the experiences gained following the FDNPP accident. The early post-nuclear-accident phase is the most important period for the dose reconstruction for the affected populations; however, it is also the most challenging period in terms of allocating the necessary monitoring resources. It is thus vital that all countries that operate nuclear power plants establish and maintain a system for nuclear emergency preparedness and response.

Monte Carlo simulations of the whole-body counter at Spiez Laboratory Switzerland: Impact of phantom size and biokinetic model

Whole-body counters (WBC) are used to detect potential intake of radioisotopes in the human body. To achieve a precise measurement of an incorporated activity, a WBC needs to be properly characterized and calibrated. However, due to technical limitations, not every geometry can be calibrated using adequate physical phantoms. To extend the use of a standard calibration to other geometries, we performed GEANT4 Monte Carlo (MC) simulations characterizing the WBC at the Spiez Laboratory, Switzerland. The aim of our project was threefold: (1) to validate our MC model against an experimental model, (2) to study the impact of a person's size on the detection efficiency of the WBC and (3) to study the impact of intake scenarios on the estimation of whole-body activity. First, we simulated the calibration of the WBC with the IGOR phantoms. Then, we computed the detection efficiency of the WBC for homogenous whole-body contamination using ICRP adult voxel phantoms scaled to sizes. We computed the bias of the activity that would be measured by the WBC relative to the activity contained in the body in case of inhalation, modeled by the ICRP biokinetic models. Our computed detection efficiency obtained with the IGOR phantoms agreed within 5% with the calibration measurements. We found that WBC efficiency depends on the weight over height ratio (w/h). We proposed a criterion for the calibration curve selection adequate for any person, and we validated this criterion using ICRP pediatric phantoms. We estimated that the precision of a whole-body activity measurement in the case of a homogeneous activity distribution is at the level of 20%. Finally, for a non-homogenous contamination of the body by inhalation, we showed that the WBC measurements can overestimate intake up to 40–80% depending on the absorption type of the substance into the blood, and the size of the scanned person. In conclusion, our study confirms the need of using phantoms with different sizes to calibrate a WBC and shows that in case of a highly non-homogenous distribution of the radioisotope in the body, the WBC may significantly overestimate the whole-body activity. To limit this bias, we recommend scanning the entire body with the detectors instead of setting them at fixed positions or increasing the distance between the detectors and the phantom.

Estimation of the Thyroid Equivalent Doses to Residents in Areas Affected by the 2011 Fukushima Nuclear Disaster Due to Inhalation of 131I Based on Their Behavioral Data and the Latest Atmospheric Transport and Dispersion Model Simulation.

It has been challenging to obtain reliable estimates of thyroid equivalent doses (TEDs) to residents involved in the 11 March 2011 Fukushima Daiichi Nuclear Power Plant (FDNPP) accident because of the shortage of direct human measurements associated with 131I, the largest contributor to the dose of concern. The present study attempted to perform the estimation of the TEDs by inhalation of 131I to residents from Namie-town, one of the most radiologically-affected municipalities, by means of the latest atmospheric transport and dispersion model (ATDM) simulations with the Worldwide version of System for Prediction of Environmental Emergency Dose Information (WSPEEDI) ver. 2, coupled with personal behavioral data containing the history of the whereabouts of individuals shortly after the accident. We analyzed 1,637 residents who underwent direct measurements with whole-body counters several months after the accident and provided their personal behavioral data. We divided the subjects into two groups based on whether the distances between their locations and the FDNPP were >20 km as of 15:00 on 12 March in relation to the timepoint of the hydrogen explosion at the Unit 1 Reactor building. As a result, the 90th percentile TEDs of the 1,249 prompt evacuees and 388 late evacuees were 3.9 mSv (adult)-6.8 mSv (10-y-old) and 24.1 mSv (adult)-35.6 mSv (5-y-old), respectively, excluding 16 persons whose TEDs exceeded 50 mSv. The 90th percentile (median) TEDs to 1-y-old children (not included in the subjects) for the prompt and late evacuation groups were 8.1 (1.0) mSv and 36.3 (19.7) mSv, respectively. Additionally, this study provided the evidence to support the view that the explosive event at the Unit 1 Reactor building on the afternoon of 12 March 2011 could have caused the critical group among Namie-town's residents, whereas the largest release event on 15 March gave relatively small doses to the residents because their exposure took place mostly at sites that were distant from the FDNPP. However, the present dose estimation has potentially large uncertainty at the individual level; further validations are thus necessary.

A METHOD TO IDENTIFY AND LOCALIZE A SINGLE HOT PARTICLE IN THE LUNGS USING AN ARRAY OF HIGH-PURITY GERMANIUM DETECTORS FOR IMPROVED ESTIMATE OF THE DEPOSITED ACTIVITY.

A new method has been developed to identify and localize a single hot particle in the lungs using an array of four high-purity germanium detectors. The method is based upon calculating a set of three count rate ratios (generated by each individual detector in the array) that are evaluated in sequence to designate whether the measured deposition can be associated with a hot particle rather than the default assumption of a uniform activity distribution. Identification and localization of the hot particle are determined from a single in vivo measurement in which detectors are positioned above and below the thorax. The method was tested using an anthropomorphic thorax phantom in which point sources of 241Am, 137Cs and 60Co were individually inserted in the lungs at 15 different locations and were measured using a scanning bed whole-body counter. Depending upon source location and photon energy, a bias of -35% up to +76% could be introduced by falsely assuming a uniform activity distribution in the lungs. This bias would directly translate to an erroneous dose estimate to the lungs. It was demonstrated that by using the appropriate detector efficiencies for the single hot particle, the bias associated with the activity determination is reduced to <10% and~2% in average.

COMPLEX RADIATION AND HYGIENIC MONITORING OF POPULATION ON RADIOLOGICALLY CONTAMINATED TERRITORIES OF ZHYTOMYR OBLAST IN 2021.

the key factors identification in radiation dose formation in population of radiologically contaminatedareas of Zhytomyr oblast in the current period of accident through complex radiation and hygienic monitoring in reference settlements in 2021. For complex radiationhygienic monitoring in Zhytomyr oblast, 10 settlements were chosen - Narodychi, Selets, Bazar, Rudnya Bazarska, Khrystynivka - zone 2, Motiyki, Zalissya, Davydky, Radcha, Nova Radcha - zone 3 of Narodychi district, in which the highest radiation doses were recorded after the accident at the Chornobyl Nuclear Power Plant. The research was carried out in June 2021. In order to determine the doses of internal radiation, 645 measurements were performed on whole body counters (WBC) (478 adults and 167 children). The 44 samples of milk, 45 samples of potatoes and vegetables, and 38 samples of wild products were collected in local farms and measured for the 137Cs and 90Sr content. Residents of the studied settlements (n = 220, 175 adults, and 45 children) were interviewed about the levels of consumption of staple foodstuffs. External radiation doses were evaluated in all the studied settlements. Mathematical, dosimetry, and radiochemical methods were applied. Annual effective radiation doses of Zhytomyr oblast population in 2021 were formedmainly due to internal radiation ones that not exceeded 1.8 mSv * year-1 in adults and 0.5 mSv * year-1 in children against the radiologically contaminated territories (RCT) criterion of 1 mSv * year-1. Intake of 137Cs with milk and wild mushrooms, which traditionally occupy a significant part of diet in Zhytomyr oblast area and have consistently high levels of radioactive cesium contamination, remains a key factor of internal radiation dose forming in residents of the surveyed settlements of Zhytomyr oblast.

OD138 - Performance evaluation of the ISOCS system as a WBC (whole body counter) for in-vivo radioactive contamination measurements

OD138 - Performance evaluation of the ISOCS system as a WBC (whole body counter) for in-vivo radioactive contamination measurements

Comparison of Indian BOMAB and ICRP voxel phantom for calibration of shadow shield whole body counter

In-vivo whole body monitors are calibrated with various types of phantoms like Bottle Mannikin absorption phantom (BOMAB), IGOR phantom, Masonite cut sheet phantom, realistic numerical phantoms (NORMAN, ICRP voxel phantom). These phantoms contain either point sources, rod sources, uniform source or radionuclides distributed in soft tissues etc. In this study the efficiency values of Shadow Shield wholebody counter (SSC) for 137Cs and 60Co obtained theoretically using ICRP adult voxel male reference phantom (ICRP-AM) having sources distributed in soft tissues and muscles ICRP-AM(S) are compared with the measured efficiencies of Indian BOMAB phantom having mid axial source distribution (BOM-I(A)). The results show that the efficiency value of BOM-I(A) for 137Cs and 60Co is 30% and 20% lower respectively compared to that of ICRP-AM(S). This is due to the variation in size, composition and source distribution between the two phantoms. Study using Indian Voxel phantom shows that the increase in the size of ICRP-AM contributed to an increase of 14% for 137Cs. In case of 60Co the size did not have any influence. Uniform distribution has 9% and 17% higher efficiency than axial distribution for 137Cs and 60Co respectively as shown by the simulation study using uniformly filled Indian BOMAB phantom (BOM-I(U)). The actual tissue composition and source distribution in soft tissue as shown by Indian voxel has efficiencies 12-14% higher compared to BOM-I(U). The systemic error due to the axial source distribution is recognized and quantified to be 22-25% lower compared to that of a realistic phantom with radionuclides in soft tissue and muscle. This study has resulted in an efficiency of the system using Indian realistic Voxel phantom. The efficiencies are 0.65 CPS/kBq for 137Cs and 0.49 CPS/kBq for 60Co.

Experimental Evaluation of 65Zn Decorporation Kinetics Following Rapid and Delayed Zn-DTPA Interventions in Rats. Biphasic Compartmental and Square-Root Law Mathematical Modeling.

The decorporation kinetics of internal radionuclide contamination is a long-term treatment raising modeling, planning, and managing problems, especially in the case of late intervention when the radiotoxic penetrated the deep compartments. The decorporation effectiveness of the highly radiotoxic 65ZnCl2 by Zn-DTPA (dosed at 3.32 mg and 5 mg/0.25 mL/100 g body weight) was investigated in Wistar male rats over a ten-day period under various treatments (i.e., as a single dose before contamination; as a single dose before and 24 h after contamination; and as daily administrations for five consecutive days starting on day 12 after contamination). The radioactivity was measured using the whole-body counting method. Mono- and bi-compartmental decorporation kinetics models proved applicable in the case of a rapid intervention. It was found that a diffusion model of the radionuclide from tissues to blood better describes the decorporation kinetics after more than ten days post treatment, and the process has been mathematically modeled as a diffusion from an infinite reservoir to a semi-finite medium. The mathematical solution led to a square-root law for describing the 65Zn decorporation. This law predicts a slower release than exponential or multiexponential equations, and could better explain the very long persistence of radionuclides in the living body. Splitting data and modeling in two steps allows a better understanding, description and prediction of the evolution of contamination, a separate approach to the treatment schemes of acute and chronic contamination.

Worker Health Monitoring Through Whole Body Counter Examination for Safety and Radiation Protection (2017-2019 Data)

Radiation protection is an action or effort taken to reduce the effects of damaging radiation exposure. Therefore, it is necessary to routinely monitor the condition of workers, among others, with a whole-body counter (WBC) either for daily activities or in a radiation emergency. In this research 78 male and female workers with an average age of 44.51 years old who have been worked for 1 up to more than 30 years at the Center for Technology of Radiation Safety and Metrology (PTKMR) - BATAN in 2018-2019 have been determined with standard procedures. The results showed that the average K-40 count for the year 2018 was 3767.35 ± 975.33 Bq. Among the 80 participants tested, internal radio-isotopic contamination with Cs-137 was detected in one person, but the levels were marginal and just exceeded the detection limit (250 Bq/body). This average value was lower than that of the previous year (2017) i.e. 4274.74 ± 740.85 Bq for 43 respondents. There is no positive correlation between radioactivity with the bodyweight of respondents but correlated positively with body mass index. It is concluded that the radio-activities of the workers of PTKMR are still within a normal range.

NATURALLY OCCURRING RADIONUCLIDE 40K BODY CONTENT OF KAKRAPAR GUJARAT SITE POPULATION

An attempt was made to investigate the naturally occurring radionuclide 40K body content of the Kakrapar Gujarat Site (India) population by using whole-body counting method. The population comprises occupational workers (regular and contract personnel working at Kakrapar Atomic Power station) and students from various educational institutions. A total of 1056 subjects of different age groups and gender were monitored for 40K body content by using a Standfast-II Whole Body Counting System. The reactor released radionuclides such as 137Cs, 60Co and 131I are not detected in occupational workers of Kakrapar Atomic Power station which indicates that occupational workers are free from radioactive contamination. Based on the activity measurement, an effective dose due to 40K was estimated for different groups of the site population based on the dietary habits, sex and age. Statistical significant correlation was not observed in any of the groups. The annual effective dose due to 40K was found to be in the range of 52-243μSvy-1 with an average of 133±35μSvy-1 for the vegetarian group (588 subjects), 60-223μSvy-1 with an average of 136±35μSvy-1 for the non-vegetarian group (468 subjects), 52-243μSvy-1 with an average of 134±35μSvy-1 for the male group (1007 subjects) and 67-203μSvy-1 with an average of 128±35μSvy-1 for the female group (49 subjects), respectively. Among the four age groups of the population studied, an effective dose due to 40K is slightly higher in the age group of 20-29 (161 subjects). The annual effective dose due to 40K reported by UNSCEAR, 1982(3) is 180μSvy-1.