Collective Effective Dose Research Articles

Spatial and temporal variations of 14C in Fucus spp. in Swedish coastal waters

Carbon-14 (14C) dominates the collective effective dose from globally dispersed long-lived radionuclides produced by and released from the nuclear power industry. Literature data on the discharge of 14C to the marine environment from nuclear power plants (NPPs) and its dispersion in the marine ecosystem are sparse. The local marine 14C background must be determined before the 14C enrichment in the marine environment from a NPP can be estimated. This is not trivial since marine activity concentrations of 14C vary spatially, partly due to long-range transport of 14C from other anthropogenic sources. We have analysed 14C in samples of several species of brown algae (Fucus spp.) collected at 45 sites along the Swedish coast in 2020. At sites remote from NPPs, the 14C activity concentrations per unit mass of carbon (here expressed as Fraction Modern, F14C) were significantly higher on the west coast than on the east coast (F14C up to about 1.10 in Skagerrak, and about 1.01, close to atmospheric levels, in the Baltic Sea and the Gulf of Bothnia). On the west coast, F14C showed a strong correlation with salinity, both of which increased towards the north. This indicates that 14C is carried from other anthropogenic sources (e.g. from the nuclear fuel reprocessing plants at La Hague and Sellafield). The highest value of F14C observed was close to the Ringhals NPP on the west coast, F14C ≈ 1.3, which is higher than expected in the terrestrial environment of this NPP. We also report on temporal variations of F14C in Fucus spp. collected at Särdal on the Swedish west coast during the period 1967–2020. The values of F14C in the Särdal marine samples collected after the 1990s are clearly higher than F14C in clean air CO2, indicating contributions of 14C of anthropogenic origin.

P198 - Collective effective dose from medical radiation exposures for the Tuscan population in 2016

P198 - Collective effective dose from medical radiation exposures for the Tuscan population in 2016

Patterns and trends of population radiation exposure and projected the risk of exposure-induced death from gamma camera examinations in Yazd Province

IntroductionThe use of nuclear medicine examinations as imaging modalities has recently increased. This study aimed to assess the radiation dose delivered to patients from common diagnostic nuclear medicine examinations and estimate the risk of exposure-induced death (REID). In addition, the frequency of nuclear medicine procedures were evaluated from 2015-2018. Materials and MethodsThe data were collected from adult patients who had undergone cardiac, skeletal, renal, lacrimal, and thyroid imaging. For each patient, the effective dose was calculated using dose conversion factors, and REID was estimated using PCXMC. The frequency of examinations between 2015 and 2018 was obtained from the hospital information system (HIS). ResultsThe highest estimated effective dose was attributed to the scans of myocardial stress (8.09 ± 1.28 mSv), myocardial rest (5.59 ± 1.27 mSv), and thyroid imaging (3.93 ± 0.55 mSv). In addition, cardiac stress examination had the highest REID values for solid cancers (212.5 ± 67.5) and bone scans had the highest REID values for leukemia (11.5 ± 2.5). A large increase in the number of myocardial perfusion scans was a significant contributor to an increase in collective effective dose from 23.37 man-Sv in 2015 to 49.47 man-Sv in 2018, a compound annual growth rate (CAGR) of 26%. ConclusionAlthough the annual frequency and per capita effective dose of nuclear medicine procedures in Yazd Province increased continuously, they were comparably lower than those reported for other countries. Despite this, the cancer risks of nuclear medicine scans at the individual level are negligible (around 0.01% excess fatal cancer risk), yet the increasing tendency for these examinations could be of concern.

Occupational radiation doses among nurses working in several medical departments in Saudi Arabia: a five-year national study

There has been an increase in the numbers of diagnostic and therapeutic procedures, which, in turn, has increased the occupational radiation doses delivered to healthcare practitioners. The aim of this study is to estimate a baseline for the occupational effective doses for five consecutive years (2016–2020) among nurses working in several medical departments in Saudi Arabia. A total of 3249 nurses were monitored from 2016 to 2020. Occupational effective doses were estimated using thermoluminescent dosimeters (TLD-100 chip) made of lithium fluoride (Li natural) LiF:Mg.Ti materials. An analysis of the dosimetry data revealed that the overall mean annual effective dose (MAED), range of the effective doses and the mean collective effective dose for nurses in selected departments during the study period were 0.85 mSv, 0.06–13.07 mSv and 46.51 man-mSv, respectively. The MAEDs for nurses were obtained from various departments, including the operating room (OR; 0.81 mSv), general X-ray (0.90 mSv), cardiac catheterization laboratory (cath-lab; 0.97 mSv), endoscopy (0.79 mSv), computed tomography (CT; 0.77 mSv), fluoroscopy (0.81 mSv), dentistry (0.92 mSv), angiography (0.91 mSv), nuclear medicine (1.01 mSv), urology (0.68 mSv), radiotherapy (0.67 mSv) and mammography (0.77 mSv). The MAED for cath-lab nurses was significantly higher than that for OR, CT and endoscopy nurses. The occupational doses among nurses in Saudi Arabia were below the recommended dose limit of 20 mSv. However, to further reduce the occupational dose, we recommend training and continuing education in radiation protection for nurses involved in radiological procedures.

OCCUPATIONAL EXPOSURE IN RADIATION APPLICATIONS IN INDIA: TRENDS AND DISTRIBUTION ANALYSIS.

Occupational exposure data in radiation applications provide a good insight on the radiation risks to workers from occupational hazards, the safe practices adopted and in deriving methods to prevent possible radiation exposures. The analysis of occupational exposure may be used to provide regulatory guidance and more focused attention to improve the safety systems, thus improving the personnel and environment safety. In this study, occupational exposure from radiation applications during 2004-18 amounting to a total number of 1951486 occupational dose data are collected and analysed using the statistical software package, SPSS. As recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation, four critical parameters viz., annual collective effective dose, average annual effective dose, individual dose distribution ratio and the annual collective dose distribution ratio for each practice are estimated. Using the trend observed for these parameters, it is predicted that occupational exposure in diagnostic radiology in the year 2023 would increase by 80% in total number of monitored with 76% increase in average collective dose and no significant change in average annual effective dose. In the same manner, nuclear medicine would see 28% of increase in radiation workers with the increase of 24% in collective dose with no significant change in average annual effective dose. Further, the reasons and area of regulatory focus for the different practices are discussed.

Study of whole-body occupational radiation exposure in the industrial radiography in Bangladesh

ObjectiveIn order to understand the complete scenario of the effectiveness of radiation protection practice in the workplace, especially in the industrial radiography and also to analyze the trends with other related studies, epidemiological studies and legal purposes, the assessment and register of the effective dose plays a significant role. Therefore, efforts have been given in the assessment of collective effective dose, mean effective dose, prediction of lifetime cancer risk, and contribution of different age group workers in the collective effective dose. MethodsThe occupational radiation exposures for 472 workers were investigated in industrial radiography throughout Bangladesh from 2015 to 2018 by using thermoluminescent dosimeter (TLD). By using a Harshaw TLD reader (Model-4500), the effective dose was measured in a quarterly basis throughout the year. Based on the value of personal dose equivalent Hp(10), database was prepared and recorded. ResultsThe collective effective dose was 36.1, 40.7, 28.8 and 37.5 man·mSv among 105, 102, 100 and 165 radiation workers in 2015, 2016, 2017 and 2018, respectively. The maximum effective dose received by radiation workers was 6.0, 7.1, 6.9 and 19.9 ​mSv in 2015, 2016, 2017 and 2018, respectively, which remained within the stipulated dose limits imposed by Nuclear Safety and Radiation Control (NSRC) Rules-1997, Bangladesh and International Commission on Radiological Protection (ICRP-103). ConclusionThis kind of monitoring would help to construct a national database that will be used by the end users to improve their implementation of optimization in occupational radiation protection in industrial radiography.

The Use of Genotoxicity Endpoints as Biomarkers of Low Dose Radiation Exposure in Interventional Cardiology.

The effect of the reportedly low ionizing radiation doses, such as those very often delivered to patients in interventional cardiology, remains ambiguous. As interventional cardiac procedures may have a significant impact on total collective effective dose, there are radiation protection concerns for patients and physicians regarding potential late health effects. Given that very low doses (<100 mSv) are expected to be delivered during these procedures, the purpose of this study was to assess the potency and suitability of current genotoxicity biomarkers to detect and quantitate biological effects essential for risk estimation in interventional cardiology. Specifically, the biomarkers γ-H2AX foci, dicentric chromosomes, and micronuclei, which underpin radiation-induced DNA damage, were studied in blood lymphocytes of 25 adult patients before and after interventional cardiac procedures. Even though the mean values of all patients as a group for all three endpoints tested show increased yields relative to baseline following medical exposure, our results demonstrate that only the γ-H2AX biomarker enables detection of statistically significant differences at the individual level (p < 0.001) for almost all patients (91%). Furthermore, 24 h after exposure, residual γ-H2AX foci were still detectable in irradiated lymphocytes. Their decline was found to vary significantly among the individuals and the repair kinetics of γ-H2AX foci was found to range from 25 to 95.6% of their maximum values obtained.

Assessment of patients’ cumulative doses in one year and collective dose to population through CT examinations

PurposeTo estimate percentage of patients undergoing multiple CT exams leading to cumulative effective dose (CED) of more than 25, 50, 75 and 100 mSv in one year and assess per capita and the collective effective dose. MethodsData from a regional hospital network was collected retrospectively using radiation dose monitoring system at 6 facilities with 8 CT scanners. The data was analyzed to find number of patients in different dose groups, their age, gender, number of CT exams and exams needed to reach 100 mSv based on age groups. ResultsIn one year 43,010 patients underwent 75,252 CT examinations. The number of exams per 1000 population was 153. Further 27% of the patients were younger than 55- years and 15.9% of them were younger than 45-year-old. A total of 0.67% of patients received a CED > 100 mSv; 3.5% had CED > 50 mSv, 11.9% with CED > 25 mSv and the maximum CED was 529 mSv. The minimum time to reach 100 mSv was a single CT exam. Seven patients received > 100 mSv in a single CT exam. 0.36% of patients had 10 or more CT exams in one year and 3.8% had 5 or more CT exams. The mean CED was 12.3 mSv, the average individual effective dose was 1.1 mSv and the collective effective dose was 521.3 person-Sv. ConclusionsThe alarming high CED received by large number of patients and with high collective dose to population requires urgent actions by all stake holders in the best interest of patient radiation safety.

Comparative evaluation of average doses of radiation of population of Irkutsk and Voronezh regions according to «Unified state system of control of individual doses»

The aim of the study was a comparative assessment of radiation doses to the population of the Voronezh and Irkutsk regions according to the unified state system for monitoring individual doses and radiation-hygienic certification. The objects of research were the territories of the Voronezh and Irkutsk regions, significantly differing in climatic conditions and resources, industrial potential, but comparable in terms of population. The subject of the study was the average territorial values of radiation doses to personnel due to the normal operation of anthropogenic sources, radiation doses to the population due to natural sources and anthropogenic background, radiation doses to patients due to the use of ionizing radiation in medical diagnostics. The method of comparative analysis of effective collective and individual average annual radiation doses was used. In the Voronezh and Irkutsk regions, the priority dose-generating factor is natural radiation, which contribution to the annual effective collective dose is 83.33 and 89.18%, respectively. At the same time, the average individual annual effective doses to the population due to natural sources of ionizing radiation in the Irkutsk region in relation to the Voronezh region are significantly higher for radon – 2,81 times, due to the content of radionuclides in drinking water – 1,93 times and external terrigenous radiation – 1,46 times, which leads to a two-fold difference in the total individual effective doses associated with natural sources of ionizing radiation. These differences are explained by the features of the physical and geographical location of territories. There are significant differences in the values of the average effective annual doses of the population due to global fallouts and past radiation accidents, because a part of the territory of the Voronezh region was exposed to radioactive contamination as a result of the accident at the Chernobyl nuclear power plant (in the Voronezh region – 0.062 mSv / year, in the Irkutsk -0.005 mSv / year). Radiography (63.15 and 67.27%) makes the leading contribution to the value of medical radiation doses, which occupy the second place in the structures of the effective collective annual doses to the population (in the Voronezh region make up 16.46%, in the Irkutsk region – 10.74%) and fluorography (31.29 and 27.41% in the regions, respectively). It was established that the radiation situation in the Voronezh and Irkutsk regions remains stable and safe.

Analysis on monitoring results of individual dose of occupational external radiation among radiation workers in Lanzhou in 2019

Objective: To analyze the individual dose level of occupational external radiation of radiation workers in Lanzhou in 2019, so as to provide reference for radiation protection and occupational health management. Methods: In April 2020, a total of 1460 radiation workers in Gansu Provincial Center for Disease Control and Prevention in 2019 were selected as the research objects. The unit nature, hospital level and occupational category of the monitored workers were collected, and the monitoring results of external radiation personal dose in 2019 were analyzed and compared. Results: In the occupational external radiation monitoring of radiation workers in Lanzhou in 2019, the effective dose of 48 persons was 1.0~<5.0 mSv, the effective dose of 2 persons was 5.0~<10.0 mSv, the annual collective effective dose was 308.21 people·mSv, and the average annual effective dose of monitored persons was 0.21 mSv/a. There was significant difference in the distribution of annual effective dose per capita among different occupational groups (H=34.43, P<0.05) . The annual effective dose per capita of nuclear medicine personnel was higher (0.56 mSv/a) , followed by interventional radiology (0.33 mSv/a) . The ratio of annual collective dose to total annual collective dose with annual individual dose more than 5 mSv (SR(5)) and the ratio of the number of staff with annual individual dose more than 1mSv to the total number of monitored personnel (NR(1)) were higher in nuclear medicine and interventional radiology personnel. The average annual effective dose distribution of diagnostic radiologists in different level hospitals was statistically significant (H=16.46, P<0.05) . The average annual effective dose in private hospitals, community hospitals and health centers was higher (0.32 mSv) , followed by county hospitals (0.23 mSv) . Conclusion: The individual dose of occupational external radiation of radiation workers in Lanzhou is generally low, and the annual effective dose of nuclear medicine and interventional radiology workers is high. The management of radiation protection should be emphasis on this people. And it is suggested to strengthen the supervision of private hospitals and update and maintain the equipment of community health centers.

Radioactivity content surveillance on canned food products in Nigeria

The radionuclides surveillance on imported can food products in Nigeria market has been investigated using High purity Germanium detector. The radioactivity concentrations of 226Ra, 232Th, 40K, 210Pb and 137Cs in selected brands of imported canned food products categorized into staple foodstuffs, beef and seafood were analyzed. The results obtained for staple foodstuffs shows a mean activity value of 12.33±3.68, 12.35±4.62, 51.48±15.12, 2.65±0.18 and 0.61±0.27 Bq kg-1 for 226Ra, 232Th, 40K, 210Pb and 137Cs respectively, while in beef food products, it is 14.41±4.79, 14.12±4.83, 50.44±14.80, 1.11± 0.07 and 0.32±0.20 Bq kg-1 respectively, and for seafood products it is 17.95±5.71, 16.24±5.48, 61.65±18.07, 1.17±0.13 and ND Bq kg-1 respectively. The overall results indicate that the natural radioactivity in the three categories of canned foodstuffs examined are well below the UNSCEAR and other regulatory bodies recommended permissible limits. The presence of 137Cs in some samples potent some degree of heavy metal contamination of those foodstuffs. The computed dose to essential organs and tissues indicates a highest dose level of 0.2 mSvy-1 which is well within the 1mSvy-1 recommended permissible level of the public. The calculated collective effective dose equivalent revealed that 97,463,16 of the total population are exposed to radiation from ingestion of the canned foods with adults most impacted. The total health detriment indicates radiological risk ratio of 1:2238 for infants, 1:2583 for children and 1:4238 for adults. From the estimated costdetriment, it is obvious that the economic benefits which is directly proportional to cost of purchase and importation put at about nine billion US dollars annually derived from consuming these imported canned food products is far above the health detriment.&#x0D; Keywords: Radioactivity surveillance, canned food, health detriment, Nigeria

MRI Screening of Lungs in the COVID-19 Pandemic at the Stages of Medical Care as a Tool to Reduce the Total Collective Dose of Radiation to the Population

Objective: to evaluate the role and place of MRI lung screening in the detection of pneumonia and patient routing.Material and methods. 500 MRI tests were performed in the period from November 1, 2020 to December 15, 2020 on the basis of more than 20 diagnostic centers of the federal MRI-Expert network. Two groups were identified. In Group 1 (control, n = 50) MRI studies were compared with CT studies in a single time interval of 0–2 days; 25 patients had a positive PCR test for SARS-CoV-2 and 25 patients were conditionally healthy. In Group 2 (effective, n = 450) mediastinal MRI was performed with lung screening on Philips 1.5 T and Siemens 1.5 T devices. The statistical analysis of the medical data base was performed.Results. During the study, mandatory and additional MRI scanning programs were identified: for Philips 1.5 T tomograph, the mandatory programs are sSSh_fb: tra and cor; THRIVE: tra (inhale/exhale); for Siemens 1.5 T – T2_BLADE: cor, tra, sag. When comparing the visual data of the control group (n = 25) with a positive PCR test in a single time interval of 0–2 days, the fact of detecting MR changes coincided with CT changes in 76% of cases (n = 19). The group of patients were examined by only one method – MRI-screening of the lungs (n = 475), pathological changes in the lungs were detected in 44% (n = 209). Localizations of the pathological changes were as follows: bilateral changes – 70.3% (n = 147), right-side changes – 19.6% (n = 41), left-side changes – 10% (n = 21); lower parts 26.8% (n = 26), average departments – 10% (n = 21), the upper divisions – 14.8% (n = 31), mid-lower 29.6% (n = 62), total – 18.6% (n = 39). The ranges of the area of lesion of the pulmonary parenchyma on MRI were graded according to MRI criteria into 4 groups (&lt; 25%, 25 – 50%, 50 – 75%, &gt; 75%). The collective radiation dose decrease was calculated for a group of patients (n = 450), which averaged 2.025 man-Sv for 1.5 months, of which 0.077 man-Sv were control studies.Conclusion. Based on the results obtained, the analyses of the possibilities of the MRI method in displaying pulmonary changes was performed. The method of MRI screening of the lungs is recognized as a possible alternative to computed tomography for dynamic monitoring in conditions of a shortage of CT records or the inability to perform it, and as a tool to reduce the collective effective dose of radiation to the population.

Calculation of natural external radiation dose rate for environmental impact assessment, case study: Abu Zenima area, Southwestern Sinai, Egypt

ABSTRACT The present article aims to assess environmental impact coming from terrestrial natural radionuclides, external gamma exposure dose radiation and the average effective annual dose value. The obtained data can be used to provide technical support for the social communication of nuclear energy bodies to understand the natural radiation background of the study area. To achieve the aim, 11271 measurements of 238U, 232Th and 40K were carried out using airborne gamma ray spectrometry for the study area. These measurements were used and converted in to specific activity for calculating the absorbed dose rate (D) and the annual effective dose (E) to infer the average annual effective dose value for the population of Abu Zenima area. The calculated specific activity of U238, Th232 and K40, absorbed dose rate, annual effective dose rate, collective dose and annual effective dose value for the population were mapped through Geographic Information System (GIS) using Arc map software version 10.5. The specific activity concentration of U238 ranged from 1 to 400 Bq/kg, Th232 ranged from 1 to 650 Bq/kg and K40 ranges from 1 to 4000 Bq/kg. The absorbed dose rate values ranged from 3.25nGy/h to 261 nGy/h. Annual effective dose rate values, varying from 21 to 9867 µSv y−1 with an average value of 172µSv y−1which is higher than the worldwide average value of 70µSv y−1 (for outdoor exposures from terrestrial radiation sources).The collective effective average dose (S), varied from 1.16 to 424.31 with an average value of 20.77 man mSv. Finally, average total population effective dose of Abu Zenima area ranged from 0.0013 to 0.0375 with an average value of 0.0129mSv. From all these results, it was concluded that Al Sahu, Al Nasb, Serabit El Khadim and Al Lehianlocalities have high background radiation.

Occupational radiation exposure among diagnostic radiology workers in the Saudi ministry of health hospitals and medical centers: A five-year national retrospective study

ObjectivesTo measure and establish a baseline for the annual mean occupational radiological dose for diagnostic radiology workers in Saudi Arabia. MethodsA retrospective analysis was performed on the effective radiation doses using Thermoluminescent dosimeters for diagnostic radiology workers in Saudi Arabia from 2015 to 2019. They were employed in 412 Saudi Ministry of Health hospitals and medical centers. The diagnostic radiology workers in this study are radiological technologists, radiologists, and medical assistants. ResultsThe study population contained 45,152 diagnostic radiology workers (58% male and 42% female). The annual mean effective doses were found to be 0.88 ± 0.002 mSv. Also, 95% of the workers received a radiation exposure dose below 1.60 mSv. The majority of the workers’ effective doses (55%) were frequently laid out between 0.50 and 1.00 mSv. An increase in the collective and mean effective doses have been observed during the study period, with a statistically significant time trend in the mean dose. ConclusionsDuring the study period, there was no incidence of an occupational dose exceeding the annual regulatory limits of 20 mSv or the investigation level I. This indicates good implementation of the radiation protection protocols in compliance with ICRP recommendations. However, enhancements in radiation protection practices should be applied for further dose reduction by supplying hospitals and medical centers with the necessary protective equipment.

A review of radiation doses and associated parameters in Western Australian mining operations that process ores containing naturally occurring radionuclides for 2018–19

Naturally occurring radionuclides (NORs) are encountered in varying concentrations in a wide range of commodities that are mined and processed in Western Australia (WA), including mineral sands, coal, phosphate ores, sandblasting materials, and the production of bauxite, titanium dioxide pigment, copper, zinc, lead, tin, tantalum and the refining of zircon.Because they have the potential for workers to receive annual doses in excess of 1 mSv, 14 mining operations in WA are required to submit an annual report of worker doses to the regulatory authority. This research provides a summary of the workforce demographics and radiation doses reported by mining operations for the 2018–19 reporting period in order to establish a benchmark against which to compare future worker exposures. The 2018–19 data is compared to that presented in the last peer-reviewed research, published in 1994 in order to evaluate changes in worker dose profiles over the intervening period.In 1992–93, the collective effective dose received by 1496 workers across seven mining operations was 2824 man.mSv, whereas in 2018–19 it had decreased to 784 man.mSv for 1474 workers in 13 operations. The maximum committed effective dose (CED) decreased by 76%, from 18 mSv (36% of the annual limit) in 1992–93 to 4.4 mSv (22% of the derived annual limit) in 2018–19. The mean CED decreased by 49%, from 1.8 mSv in 1992–93 to 0.97 mSv in 2018–19.As a result of revised DC’s published in ICRP-137 and ICRP-141, the impacts upon the mean CED per unit intake of alpha activity arising from inhalation of insoluble NORs-containing dusts, and contribution to CED from inhalation of radon, thoron and their progeny will require evaluation for individual mining operations in the WA mining industry.

Status and Trend of Occupational Radiation Exposure in Radiotherapy and Diagnostic X-ray Practices in Bangladesh

Introduction: The evaluation of occupational exposure and related trends due to external ionizing radiation in diagnostic and therapeutic purposes has become crucial to understand the implementation of regulatory acts and technological advancement. This study describes the status of occupational radiation exposure in radiotherapy (RADT) and diagnostic X-ray (DRA) sector and the comparison with related research.Materials and Methods: Overall, 12141 number of radiation workers were monitored using thermoluminescent dosimeters (TLDs) which read-out by Harshaw TLD Reader (Model 4500) on a quarterly basis. Several parameters such as annual collective effective dose, average annual effective dose, collective and individual dose distribution, and the probability of cancer risk were analyzed.Results: The number of monitored workers increased by around 35%, whereas the number of radiation workers received a measurable amount of doses decreased by around 37% during 2014-2018. The annual average effective doses in RADT and DRA were in the range of 0.017-0.1112 and 0.076-0.1702 mSv, respectively. The results indicate that more than 94% of the total collective dose was for the non-physician group. Among exposed radiation workers, almost 78% received doses below 1mSv and

A Comprehensive Approach for Estimating Collective and Average Effective Doses of Galactic Cosmic Radiation Received by Pilots.

This study proposes a feasible and comprehensive approach for estimating collective and average effective doses of galactic cosmic radiation received by pilots on the basis of data in publicly available civil aviation annual statistical reports. Large uncertainties are associated with the estimation of these quantities because the radiation environment at aviation altitudes is complex, and a large number of flights operated by various air carriers is involved. A best estimate can be obtained through this approach because it considers all passenger, cargo, and charter flights operated during a long period of time instead of subjectively selecting some representative flights for dose evaluation. The approach becomes feasible and practical with the aid of a special feature called automatic batch analysis in the NTHU Flight Dose Calculator. There are two international airlines in Taiwan: China Airlines and EVA Air. As a demonstration, the collective effective dose received by the 2,513 pilots from the two airlines in 2018 was estimated to be 4,947 person-mSv, and the average effective dose per pilot was 1.97 mSv. These estimates were considered representative because they were based on all 151,526 flight segments operated that year. The assessment of the annual effective doses received by pilots in Taiwan from 2006 to 2018 was performed. The results varied in the range of 1.70-2.97 mSv because of variations in solar activity and operational flight routes. A regression model that can effectively reproduce the derived average effective dose rates on board aircraft was obtained for future application in aircrew dosimetry.

ESTIMATION OF OCCUPATIONAL RADIATION EXPOSURE FOR MEDICAL WORKERS IN RADIOLOGY AND CARDIOLOGY IN THE UNITED ARAB EMIRATES: NINE HOSPITALS EXPERIENCE.

Occupational radiation exposure for medical workers in radiology and cardiology was analyzed in nine hospitals in the UAE between 2002 and 2016. The purpose of the study was to determine the time trend and the differences in occupational radiation exposure among worker groups and hospitals in the country. Readings of 5700 thermoluminescence dosimeters (TLDs) were obtained from 1011 medical workers and grouped into 5 worker groups (radiographers, diagnostic radiologists, nurses, cardiologists and physicians). The mean annual effective dose was from 0.38 to 0.62mSv per worker. Even though an increase in the collective effective dose has been noticed during the study period, no significant time trend was observed in the mean effective dose. Furthermore, cardiologists received higher mean and maximum effective doses than the other worker groups. The annual effective doses were below the limits set by national legislation and international standards, and for the average worker, the likelihood of high exposure is small. However, improvements in radiation protection practices could be implemented to reduce occupational radiation dose to cardiologists, who were the most exposed worker group in this study.

CONTEMPORARY COLLECTIVE EFFECTIVE DOSE TO THE POPULATION FROM X-RAY AND NUCLEAR MEDICINE EXAMINATIONS-CHANGES OVER LAST 10 YEARS IN FINLAND.

Contemporary collective effective doses to the population from x-ray and nuclear medicine examinations in Finland in 2018 was estimated. The estimated effective dose per caput from x-ray examinations increased from year 2008 to 2018 respectively from 0.45 mSv to 0.72 mSv and from nuclear medicine examinations from 0.03 mSv to 0.04 mSv. The proportional dose due to CT examinations of the total collective effective dose from all x-ray examinations increased from 58% in 2008 to 70% in 2018 and the dose did not change substantially in total when new conversion factors were applied. The collective effective dose from conventional plain radiography did not change substantially during the last ten years while the new (ICRP 103) tissue weighting factors were taken into use in 2018, however frequencies of examinations in total decreased. The collective effective dose from CT in nuclear medicine tripled between 2009 and 2018.

Patient Exposure from Radiologic and Nuclear Medicine Procedures in the United States: Procedure Volume and Effective Dose for the Period 2006-2016.

Background Comprehensive assessments of the frequency and associated doses from radiologic and nuclear medicine procedures are rarely conducted. The use of these procedures and the population-based radiation dose increased remarkably from 1980 to 2006. Purpose To determine the change in per capita radiation exposure in the United States from 2006 to 2016. Materials and Methods The U.S. National Council on Radiation Protection and Measurements conducted a retrospective assessment for 2016 and compared the results to previously published data for the year 2006. Effective dose values for procedures were obtained from the literature, and frequency data were obtained from commercial, governmental, and professional society data. Results In the United States in 2006, an estimated 377 million diagnostic and interventional radiologic examinations were performed. This value remained essentially the same for 2016 even though the U.S. population had increased by about 24 million people. The number of CT scans performed increased from 67 million to 84 million, but the number of other procedures (eg, diagnostic fluoroscopy) and nuclear medicine procedures decreased from 17 million to 13.5 million. The number of dental radiographic and dental CT examinations performed was estimated to be about 320 million in 2016. Using the tissue-weighting factors from Publication 60 of the International Commission on Radiological Protection, the U.S. annual individual (per capita) effective dose from diagnostic and interventional medical procedures was estimated to have been 2.9 mSv in 2006 and 2.3 mSv in 2016, with the collective doses being 885 000 and 755 000 person-sievert, respectively. Conclusion The trend from 1980 to 2006 of increasing dose from medical radiation has reversed. Estimated 2016 total collective effective dose and radiation dose per capita dose are lower than in 2006. © RSNA, 2020 See also the editorial by Einstein in this issue.