Showing papers in "Journal of Radiological Protection in 2021"
TL;DR: The International Commission on Radiological Protection (ICRP) has embarked on a review and revision of the System of Radiological protection that will update the 2007 General Recommendations in ICRP Publication 103.
Abstract: The International Commission on Radiological Protection (ICRP) has embarked on a review and revision of the System of Radiological Protection that will update the 2007 General Recommendations in ICRP Publication 103. This is the beginning of a process that will take several years, involving open and transparent engagement with organisations and individuals around the world. While the System is robust and has performed well, it must adapt to address changes in science and society to remain fit for purpose. The aim of this paper is to encourage discussions on which areas of the System might gain the greatest benefit from review, and to initiate collaborative efforts. Increased clarity and consistency are high priorities. The better the System is understood, the more effectively it can be applied, resulting in improved protection and increased harmonisation. Many areas are identified for potential review including: classification of effects, with particular focus on tissue reactions; reformulation of detriment, potentially including non-cancer diseases; re-evaluation of the relationship between detriment and effective dose, and the possibility of defining detriments for males and females of different ages; individual variation in the response to radiation exposure; heritable effects; and effects and risks in non-human biota and ecosystems. Some of the basic concepts are also being considered, including the framework for bringing together protection of people and the environment, incremental improvements to the fundamental principles of justification and optimisation, a broader approach to protection of individuals, and clarification of the exposure situations introduced in 2007. In addition, ICRP is considering identifying where explicit incorporation of the ethical basis of the System would be beneficial, how to better reflect the importance of communications and stakeholder involvement, and further advice on education and training. ICRP invites responses on these and other areas relating to the review of the System of Radiological Protection.
82 citations
TL;DR: The International Commission on Radiological Protection has recently published a report (ICRP Publication 147;Ann. ICRP50, 2021) on the use of dose quantities in radiological protection, under the same authorship as this Memorandum as mentioned in this paper.
Abstract: The International Commission on Radiological Protection has recently published a report (ICRP Publication 147;Ann. ICRP50, 2021) on the use of dose quantities in radiological protection, under the same authorship as this Memorandum. Here, we present a brief summary of the main elements of the report. ICRP Publication 147 consolidates and clarifies the explanations provided in the 2007 ICRP Recommendations (Publication 103) but reaches conclusions that go beyond those presented in Publication 103. Further guidance is provided on the scientific basis for the control of radiation risks using dose quantities in occupational, public and medical applications. It is emphasised that best estimates of risk to individuals will use organ/tissue absorbed doses, appropriate relative biological effectiveness factors and dose-risk models for specific health effects. However, bearing in mind uncertainties including those associated with risk projection to low doses or low dose rates, it is concluded that in the context of radiological protection, effective dose may be considered as an approximate indicator of possible risk of stochastic health effects following low-level exposure to ionising radiation. In this respect, it should also be recognised that lifetime cancer risks vary with age at exposure, sex and population group. The ICRP report also concludes that equivalent dose is not needed as a protection quantity. Dose limits for the avoidance of tissue reactions for the skin, hands and feet, and lens of the eye will be more appropriately set in terms of absorbed dose rather than equivalent dose.
31 citations
TL;DR: In this paper, a visualization method is examined to facilitate the understanding of the spread of scattered radiation in radiography, computerized tomography (CT), and angiography rooms, and the application of this system for radiation protection education is proposed.
Abstract: When working in radiology and patient assistance in medical facilities, radiation workers need to understand how to properly protect themselves and others from scattered radiation. In this study, a visualization method is examined to facilitate the understanding of the spread of scattered radiation in radiography, computerized tomography (CT), and angiography rooms, and the application of this system for radiation protection education is proposed. X-ray radiography, X-ray CT, and angiography rooms were constructed using the particle and heavy ion transport code system (PHITS), and the scattered radiation distributions that occurred when a patient was irradiated with X-rays were simulated. The three-dimensional distribution of each moment was continuously displayed to create a four-dimensional distribution. Using the obtained data, a radiation protection education seminar was conducted that included exercises to allow the students to confirm the presence of scattered radiation from any direction. The effectiveness of the scattered radiation visualization data was evaluated using a interview. The position of the assistant for conducting standing chest radiographs that experienced the least scattered radiation was determined to be at the side and foot side of the patient. As a result of an interview that was provided to the participants following the seminar, the effectiveness of this system for providing education about radiation protection was confirmed. The visualization method allowed the students to better understand the behaviour of radiation and the sources of scattered radiation. The visualization of three- and four-dimensional scattered radiation distributions in radiological examination rooms can intuitively enhance the understanding of the spread of invisible radiation and the appropriate methods of mitigating radiation exposure.
25 citations
TL;DR: This article provides an overview on the generation and detection of x-rays in laser material processing, as well as on the handling of this radiation risk in the framework of radiological protection.
Abstract: Laser processing with ultra-short laser pulses enables machining of materials with high accuracy and throughput. The development of novel laser technologies with laser pulse repetition rates up to the MHz range opened the way for industrial manufacturing processes. From a radiological point of view this evolution is important, because x-ray radiation can be generated as an unwanted side effect in laser material processing. Even if the emitted x-ray dose per pulse is comparably low, the x-ray dose can become hazardous to health at high laser repetition rates. Therefore, radiation protection must be considered. This article provides an overview on the generation and detection of x-rays in laser material processing, as well as on the handling of this radiation risk in the framework of radiological protection.
22 citations
TL;DR: However, the slope of the dose-response for solid cancers expressed in terms of the excess relative risk per unit dose, ERR/Gy, differs between the International Nuclear Workers Study (INWORKS) and studies of the Mayak workforce in Russia, such that when compared with the slope derived from the atomic-bomb survivors, INWORKS does not provide obvious support for the use in radiological protection of a dose and dose-rate effectiveness factor greater than one whereas the mayak workforce apparently does as discussed by the authors.
Abstract: Epidemiological studies of those exposed occupationally to ionising radiation offer an important opportunity to directly check the assumptions underlying the international system of radiological protection against low-level radiation exposures. Recent nuclear worker studies, notably the International Nuclear Workers Study (INWORKS) and studies of the Mayak workforce in Russia, provide powerful investigations of a wide range of cumulative photon doses received at a low dose-rate over protracted periods, and broadly confirm radiation-related excess risks of leukaemia and solid cancers at around the levels predicted by standard risk models derived mainly from the experience of the Japanese atomic-bomb survivors acutely exposed principally to gamma radiation. However, the slope of the dose-response for solid cancers expressed in terms of the excess relative risk per unit dose, ERR/Gy, differs between INWORKS and Mayak, such that when compared with the slope derived from the atomic-bomb survivors, INWORKS does not provide obvious support for the use in radiological protection of a dose and dose-rate effectiveness factor greater than one whereas the Mayak workforce apparently does. This difference could be a chance effect, but it could also point to potential problems with these worker studies. Of particular concern is the adequacy of recorded doses received in the early years of operations at older nuclear installations, such as the potential for 'missed' photon doses. A further issue is how baseline cancer rates may influence radiation-related excess risks. There is scope for a considerable increase in the statistical power of worker studies, with longer follow-up capturing more deaths and incident cases of cancer, and further workforces being included in collaborative studies, but the difficulties posed by dosimetry questions should not be ignored and need to be the subject of detailed scrutiny.
22 citations
TL;DR: In this paper, an anthropomorphic head phantom was used to examine the dose of x-ray radiation that physicians are exposed to during endoscopic retrograde cholangiopancreatography (ERCP).
Abstract: Increased x-ray exposure to physicians' eye lenses during radiology procedures is a significant concern. In this study, x-ray exposure to the eye was measured using an anthropomorphic head phantom, with and without radiation-protective devices, to examine the dose of x-ray radiation that physicians are exposed to during endoscopic retrograde cholangiopancreatography (ERCP). X-ray exposure of the eye was measured using novel dedicated direct eye lens dosimeters that could specifically measureHp(3) during the ERCP procedure. The spatial dose in the height direction of the physician was measured using an ionization chamber dosimeter. Eye dosimeters were attached inside and outside the lead (Pb) glasses attached to the head of the human phantom to demonstrate its protective effect. Irradiation from the system lasted for 30 min. When the overcouch x-ray tube system is used, the cumulative radiation dose over the 30 min x-ray fluoroscopy time, without the use of radiation-protective devices, to the left and right eyes was 3.7 and 1.5 mSv, respectively. This dose was estimated to be the dose to the lens per therapeutic ERCP examination. With radiation-protective glasses, the dose reduced to 1.8 and 1.0 mSv for the left and right eye, respectively. The results of our study indicated that radiation exposure to the eye was reduced by up to 80.0% using Pb glasses and by 96.8% using radiation-protective curtains. Our study indicates that a physician's maximum radiation exposure to the eyes during an ERCP procedure may be above the level recommended by the International Commission on Radiological Protection when the physician does not use radiation-protective devices. The eyewear, which is larger and fitted more closely to the face, provided a better protection effect even with a low lead equivalence, demonstrating that the shape of eyewear is important for protective function.
18 citations
TL;DR: In this article, a comprehensive literature search was done in the popular databases such as PubMed and Google Scholar under the key words 'p(a)ediatric DRL', 'dose reference level', 'diagnostic reference level' and 'DRL'. Twenty-three articles originating from 15 countries were included.
Abstract: This study aims to review the existing literature on diagnostic reference levels (DRLs) in paediatric computed tomography (CT) procedures and the methodologies for establishing them. A comprehensive literature search was done in the popular databases such as PubMed and Google Scholar under the key words 'p(a)ediatric DRL', 'dose reference level', 'diagnostic reference level' and 'DRL'. Twenty-three articles originating from 15 countries were included. Differences were found in the methods used to establish paediatric CT DRLs across the world, including test subjects, reference phantom size, anatomical regions, modes of data collection and stratification techniques. The majority of the studies were based on retrospective patient surveys. The head, chest and abdomen were the common regions. The volume computed tomography dose index (CTDIvol) and dose-length product (DLP) were the dosimetric quantities chosen in the majority of publications. However, the size-specific dose estimate was a growing trend in the DRL concept of CT. A 16 cm diameter phantom was used by most of the publications when defining DRLs for head, chest and abdomen. The majority of the DRLs were given based on patient age, and the common age categories for head, chest and abdomen regions were 0-1, 1-5, 5-10 and 10-15 years. The DRL ranges for the head region were 18-68 mGy (CTDIvol) and 260-1608 mGy cm (DLP). For chest and abdomen regions the variations were 1.0-15.6 mGy, 10-496 mGy cm and 1.8-23 mGy, 65-807 mGy cm, respectively. All these DRLs were established for children aged 0-18 years. The wide range of DRL distributions in chest and abdomen regions can be attributed to the use of two different reference phantom sizes (16 and 32 cm), failure to follow a common methodology and inadequate dose optimisation actions. Therefore, an internationally accepted protocol should be followed when establishing DRLs. Moreover, these DRL variations suggest the importance of establish a national DRL for each country considering advanced techniques and dose reduction methodologies.
17 citations
TL;DR: In this article, the authors developed a new generation of adult and pediatric reference computational phantoms, named "mesh-type reference computations (MRCPs)" that can overcome the limitations of voxel-type Reference Computational Phantoms (VRCPs) of ICRP Publications 110 and 143.
Abstract: In 2016, the ICRP launched Task Group 103 (TG 103) for the explicit purpose of developing a new generation of adult and pediatric reference computational phantoms, named "mesh-type reference computational phantoms (MRCPs)," that can overcome the limitations of voxel-type reference computational phantoms (VRCPs) of ICRP Publications 110 and 143 due to their finite voxel resolutions and the nature of voxel geometry. After completing the development of the adult MRCPs, TG 103 has started the development of pediatric MRCPs comprising 10 phantoms (male and female versions of the reference newborn, 1-year-old, 5-year-old, 10-year-old, and 15-year-old). As part of the TG 103 project, within the present study, the skeletal systems, one of the most important and complex organ systems of the body, were developed for each phantom age and sex. The developed skeletal systems, while closely preserving the original bone topology of the pediatric VRCPs, present substantial improvements in the anatomy of complex and/or small bones. In order to investigate the dosimetric impact of the developed skeletons, the average absorbed doses and the specific absorbed fractions (SAFs) for radiosensitive skeletal tissues (i.e. active marrow and bone endosteum) were computed for some selected external and internal exposure cases, which were then compared with those calculated with the skeletons of pediatric VRCPs. The comparison result showed that the dose values of the pediatric MRCPs were generally similar to those of the pediatric VRCPs for highly penetrating radiations (e.g. photons >200 keV); however, for weakly penetrating radiations (e.g. photons ≤200 keV and electrons), significant differences up to a factor of 140 were observed.
16 citations
TL;DR: In this paper, it was shown that despite using the best possible approaches to justification and optimization including as well use of DRLs, a very large number of patients are receiving doses in excess of 100 mSv of effective dose or organ doses exceeding 100 mGy.
Abstract: The radiation protection principles of justification, optimization, and dose limitation as enumerated by the International Commission on Radiological Protection have been guiding light for the profession for over three decades. The dose limitation does not apply to medical exposure but keeping patients' doses low is achieved through optimization, particularly by developing and using diagnostic reference levels (DRLs). There are new findings that demonstrate that despite using the best possible approaches to justification and optimization including as well use of DRLs, a very large number of patients are receiving doses in excess of 100 mSv of effective dose or organ doses exceeding 100 mGy. A non-ignorable fraction of patients is receiving such high doses in a single day. The magnitude of such patients creates the need for a relook into the principles with the intent to understand what can be done to attend to today's problems. A look at other areas such as approaches, and principles used in the pharmaceutical industry and in traffic management throws some light into what can be learnt from these examples. It appears that the system needs to be enriched to deal with the protection of the individual patient. The currently available approaches and even the principles are largely based on the protection of the population or group of patients. The third level of justification for individual needs further refinement to take into account series of imaging many patients are needing, and cumulative radiation doses involved, many of which happen in a short duration of 1 to 5 years. There is every likelihood of patient radiation doses continuing to increase further that underscores the need for timely attention. This paper provides several suggestions to deal with the situation.
15 citations
TL;DR: The effect of external radiation on lymphoma, including non-Hodgkin lymphoma (NHL), Hodgkin lymphomas (HL) and multiple myeloma (MM) incidence was evaluated in the National Registry for Radiation Workers (NRRW) based upon the 3rd analysis cohort but with an additional 10 years of follow-up as mentioned in this paper.
Abstract: The effect of external radiation on lymphoma, including non-Hodgkin lymphoma (NHL), Hodgkin lymphoma (HL) and multiple myeloma (MM) incidence was evaluated in the National Registry for Radiation Workers (NRRW) based upon the 3rd analysis cohort but with an additional 10 years of follow-up. The study includes 172,452 workers, of whom (90%) were men with 3.6 million person-years of follow-up from 1950 through to the end of 2011. A total of 711 cases of NHL, 113 cases of HL and 279 cases of MM were registered. Poisson regression was used to estimate the excess relative risk (ERR) per unit of cumulative exposure to ionising radiation. A statistically significant association was found between radiation dose and the incidence of NHL and MM. There was no evidence of radiation associated excess risk for HL. The reported associations are based on a very small proportion of exposed workers, in particular among workers with cumulative doses above 0.5 Sv so should be treated with caution, further investigations are necessary to confirm our results.
14 citations
TL;DR: The purpose of this article is to review the SSDE concept and the factors influencing it and to potentially increase awareness among CT users of the effective utilization of SSDE as a tool to aid in the optimization of radiation dose in CT.
Abstract: The actual dose received during a Computed Tomography (CT) examination depends on both patient size and the radiation output of the scanner. To represent the actual patient morphometric, a new radiation dose metric named "Size-Specific Dose Estimates (SSDE) had been developed by the American Association of Physicists in Medicine (AAPM) in 2011. The purpose of this article is to review the SSDE concept and the factors influencing it. Moreover, the appropriate methodology of SSDE determination and the application of SSDE as a DRL quantity was critically analyzed based on the data available in the literature. It is expected that this review could potentially increase the awareness among CT users on the effective utilization of SSDE as a tool aid in the optimization of radiation dose in CT.
TL;DR: In this article, the authors used FLUKA, MCNP and GEANT4 radiation transport Monte-Carlo simulation codes to perform the calculations for neutrons and compared the results with those of the three codes.
Abstract: Dose equivalent limits for single organs are recommended by the ICRP (International Commission for the Radiological Protection publication 103). These limits do not lend themselves to be measured. They are assessed by convoluting conversion factors with particle fluences. The Fluence-to-Dose conversion factors are tabulated in the ICRP literature. They allow assessing the organ dose of interest using numerical simulations. In particular, the literature lacks the knowledge of local skin equivalent dose (LSD) coefficients for neutrons. In this article, we compute such values for neutron energies ranging from 1 meV to 15 MeV. We use FLUKA, MCNP and GEANT4 Radiation transport Monte-Carlo simulation codes to perform the calculations. A comparison between these three codes is performed. These calculated values are important for radiation protection studies and radiotherapy applications.
TL;DR: In this article, the pediatric mesh-type Reference Computational Phantoms (MRCPs) were constructed by converting the voxel-type reference phantoms to a high-quality mesh format with substantial enhancements in the detailed anatomy of the small and complex organs and tissues.
Abstract: Very recently, Task Group 103 of the International Commission on Radiological Protection (ICRP) completed the development of the pediatric Mesh-type Reference Computational Phantoms (MRCPs) comprising ten phantoms (newborn, 1-year-old, 5-year-old, 10-year-old, and 15-year-old males and females). The pediatric MRCPs address the limitations of ICRPPublication 143's pediatric reference computational phantoms, which are in voxel format, stemming from the nature of the voxel geometry and the limited voxel resolutions. The pediatric MRCPs were constructed by converting the voxel-type reference phantoms to a high-quality mesh format with substantial enhancements in the detailed anatomy of the small and complex organs and tissues (e.g., bones, lymphatic nodes, and extra-thoracic (ET) region). Besides, the pediatric MRCPs were developed in consideration of the intra-organ blood contents and by modelling the micron-thick target and source regions of the skin, lens, urinary bladder, alimentary tract organs, and respiratory tract organs prescribed by the ICRP. For external idealized exposures, the pediatric MRCPs provide very similar effective dose coefficients to those from the ICRP-143 phantoms but significantly different values for weakly penetrating radiations (e.g., the difference of ~20,000 times for 10-keV electron beams). This paper introduces the developed pediatric MRCPs with a brief explanation of the construction process. Then, it discusses their computational performance in Geant4, PHITS, and MCNP6 in terms of memory usage and computation speed and their impact on dose calculations by comparing their calculated values of effective dose coefficients for external exposures with those of the voxel-type reference phantoms.
TL;DR: Scar-tissue compartments corresponding to the larynx, bronchi, bronchioles and alveolar-interstitial regions were added to the existing human respiratory tract model structure and it was shown that approximately 30% of plutonium activity in the lung was sequestered in scar tissues.
Abstract: The U.S. Transuranium and Uranium Registries whole-body tissue donor Case 0407 had an acute intake of 'high-fired' plutonium oxide resulting from a glove-box fire in a fabrication plant at a nuclear defence facility. The respiratory tract of this individual was dissected into five regions (larynx, bronchi, bronchioles, alveolar-interstitial, and thoracic lymph nodes) and analysed for plutonium content. The activities in certain compartments of the respiratory tract were found to be higher than expected from the default models described in publications of the International Commission on Radiological Protection. Because of the extremely slow rate of dissolution of the material inhaled, the presence of bound fraction is incapable of explaining the higher-than-expected retention. A plausible hypothesis-encapsulation of plutonium in scar tissues-is supported by the review of literature. Therefore, scar-tissue compartments corresponding to the larynx, bronchi, bronchioles and alveolar-interstitial regions were added to the existing human respiratory tract model structure. The transfer rates between these compartments were determined using Markov Chain Monte Carlo analysis of data on urinary excretion, lung counts and post-mortem measurements of the liver, skeleton and regional retention in the respiratory tract. Modelling of the data showed that approximately 30% of plutonium activity in the lung was sequestered in scar tissues. The dose consequence of such sequestration is qualitatively compared against that of chemical binding.
TL;DR: It is recommended that dose values from dosimeters worn over a protective apron be reduced by a factor of 20 for estimating mean organ doses to tissues located in the torso and that 15% of the marrow should be assumed to remain unshielded for exposure scenarios when aprons are worn.
Abstract: The study of low dose and low-dose rate exposure is of central importance in understanding the possible range of health effects from prolonged exposures to radiation. The One Million Person Study of Radiation Workers and Veterans (MPS) of low-dose health effects was designed to evaluate radiation risks among healthy American workers and veterans. The MPS is evaluating low-dose and dose-rate effects, intakes of radioactive elements, cancer and non-cancer outcomes, as well as differences in risks between women and men. Medical radiation workers make up a large group of individuals occupationally exposed to low doses of radiation from external x-ray / gamma exposures. For the MPS, about 100,000 U.S. medical radiation workers have been selected for study. The approach to the complex dosimetry circumstances for such workers over 3 to 4 decades of occupation were initially and broadly described in NCRP Report No. 178. NCRP Commentary No. 30 provides more detail and describes an optimum approach for using personal monitoring data to estimate lung and other organ doses applicable to the cohort and provides specific precautions/considerations applicable to the dosimetry of medical radiation worker organ doses for use in epidemiologic studies. The use of protective aprons creates dosimetric complexity. It is recommended that dose values from dosimeters worn over a protective apron be reduced by a factor of 20 for estimating mean organ doses to tissues located in the torso and that 15% of the marrow should be assumed to remain unshielded for exposure scenarios when aprons are worn. Conversion coefficients relating personal dose equivalent, Hp(10) in mSv, to mean absorbed doses to organs and tissues, DT in mGy, for females and males for six exposure scenarios have been determined and presented for use in the MPS. This Memorandum summarizes several key points in NCRP Commentary No. 30.
TL;DR: The radiation protection community must get better at placing its research within the appropriate perspective and context, something that is far too rarely the case in discussions on radiation matters outside of the scientific community.
Abstract: As far as carcinogens are concerned, radiation is one of the best studied, having been researched for more than 100 years. Yet, radiation remains feared in many contexts as a result of its invisibility, its relationship with cancers and congenital disorders, aided by a variety of heuristics and reinforced by negative imagery. The strong socio-psychological response relating to nuclear energy has made radiation a classical case in the risk literature. This is reflected clearly following the nuclear accidents that have taken place, where the socio-psychological impacts of the clear dissonance between real and perceived health effects due to radiation exposure have caused considerable health detriment, outweighing the actual radiological impacts. Despite considerable efforts to normalise humankind's relationship with radiation, there has been little shift away from the perceived uniqueness of the health risks of radiation. One consistent issue is the failure to place radiation within its proper perspective and context, which has ensured that radiophobia has persisted. The radiation protection community must get better at placing its research within the appropriate perspective and context, something that is far too rarely the case in discussions on radiation matters outside of the scientific community. Each member of the radiation protection community has an ethical, professional and moral obligation to set the record straight, to challenge the misconceptions and factual errors that surround radiation, as well as putting it into the proper perspective and context. Failing to do so, the well-established harms of radiophobia will remain, and the many benefits of nuclear technology risk being withheld.
TL;DR: Experimental contamination testing and computational Monte Carlo simulation techniques (GEANT4) were employed to understand how radioactive contamination pick-up on three different robotic vehicles would affect their detection accuracy.
Abstract: Ground robotic vehicles are often deployed to inspect areas where radioactive floor contamination is a prominent risk. However, the accuracy of detection could be adversely affected by enhanced radiation signal through self-contamination of the robot occurring over the course of the inspection. In this work, it was hypothesised that a six-legged robot could offer advantages over the more conventional ground robotic devices such as wheeled and tracked rovers. To investigate this, experimental contamination testing and computational Monte Carlo simulation techniques (GEANT4) were employed to understand how radioactive contamination pick-up on three different robotic vehicles would affect their detection accuracy. Two robotic vehicles were selected for comparison with the hexapod robot based on their type of locomotion; a wheeled rover and a tracked rover. With the aid of a non-toxic fluorescent tracer dust, the contamination received by the all three vehicles when traversing a contaminated area was initially compared through physical inspection using high definition cameras. The parametric results from these tests where used in the computational study carried out in GEANT4. A cadmium zinc telluride detector was simulated at heights ranging from 10 to 50 cm above each contaminated vehicle, as if it were mounted on a plinth. Assuming a uniform activity of 60 Bq cm-2on all contaminated surfaces, the results suggested that due to the hexapod's small ground-contacting surface area and geometry, radiation detection rates using an uncollimated detector are likely to be overestimated by between only 0.07%-0.12%, compared with 3.95%-8.43% and 1.75%-14.53% for the wheeled and tracked robot alternatives, respectively.
TL;DR: In this article, the date of a single irradiation with 12 mSv within a monitoring interval of 42 days from glow curves of novel TL-DOS personal dosimeters developed by the Materialprufungsamt NRW in cooperation with TU Dortmund University.
Abstract: The time- or temperature-resolved detector signal from a thermoluminescence dosimeter can reveal additional information about circumstances of an exposure to ionizing irradiation. We present studies using deep neural networks to estimate the date of a single irradiation with 12 mSv within a monitoring interval of 42 days from glow curves of novel TL-DOS personal dosimeters developed by the Materialprufungsamt NRW in cooperation with TU Dortmund University. Using a deep convolutional network, the irradiation date can be predicted from raw time-resolved glow curve data with an uncertainty of roughly 1-2 days on a 68% confidence level without the need for a prior transformation into temperature space and a subsequent glow curve deconvolution. This corresponds to a significant improvement in prediction accuracy compared to a prior publication, which yielded a prediction uncertainty of 2-4 days using features obtained from a glow curve deconvolution as input to a neural network.
TL;DR: In this paper, a web-based database system for the analysis of environmental monitoring data has been proposed for the evaluation and implementation of countermeasures to mitigate the effects of the accident at the Fukushima Daiichi Nuclear Power Plant.
Abstract: An enormous amount of environmental monitoring data has been acquired by various organisations for the evaluation and implementation of countermeasures to mitigate the effects of the accident at the Fukushima Daiichi Nuclear Power Plant. However, it is difficult to collate, compare, and analyse this data because it was published in different formats at different sites according to the respective objectives of the publishing organisations. Moreover, these organisations have been accumulating data in large volumes for over nine years after the accident. We established procedures to collect this data, convert them into a unified format, classify them according to categories, and make the data accessible on a web-based database system. The database contains environmental monitoring data on air dose rates, ground deposition densities, and concentrations in various environmental samples such as soil, water, and food. This data is being provided not only in numerical format for quantitative analysis but also as distribution maps and time-series graphs for visual understanding. The database system enabled us to spatially and temporally compare large volumes of monitoring data. By using the database functions, characteristics of some representative data in the database was clarified.
TL;DR: The main contribution to the contamination was that of gas aerosol emissions of the Mayak Production Association in 1950-s (total activity was 38 PBq, mainly 131I), liquid radioactive waste releases into the Techa River in 1949-1956, including long-lived 90Sr and 137Cs, as well as accidental atmospheric releases as a result of the thermochemical explosion of the storage tank for liquid radioactive wastes in 1957 (74 PBq), relatively short-lived radionuclides were the main contributors as mentioned in this paper.
Abstract: The process of the nuclear weapon production in 1949-1987 was accompanied by the generation of a great amount of radioactive waste. Waste processing operations and controls on discharges at this time were not to the same standard as today. Because of this, vast territories of the Urals region of Russia surrounding the Mayak Production Association were exposed to routine and accidental radioactive contamination. The greatest contribution to the contamination was that of gas aerosol emissions of the Mayak PA in 1950-s (total activity was 38 PBq, mainly 131I), liquid radioactive waste releases into the Techa River in 1949-1956 (total activity - 115 PBq, including long-lived 90Sr and 137Cs), as well as accidental atmospheric releases as a result of the thermochemical explosion of the storage tank for liquid radioactive waste in 1957 (74 PBq, relatively short-lived radionuclides were the main contributors). Protective measures helped to relieve the pressing problem of population safety in 1950-1960s. But they led to appearance of new sources of contamination of the territory surrounding the Mayak PA - the Lake Karachay (total activity of beta-emitters was 4,400 PBq) and Techa Cascade of Reservoirs (total activity - 8 PBq). Owing to natural radioactive decay and rehabilitation measures, the radiation situation in the East Urals Radioactive Trace (EURT) has improved considerably over the years. Economic activity was partially restored in these territories. Only the most contaminated territory of the East Urals Radioactive reserve cannot be used for any economic activities up to the present day. Marked non-uniformity of radioactive contamination of the EURT and the Techa River floodplain, as well as the radionuclide washout from the Lake Karachay and Techa Cascade of Reservoirs into the underground waters and the Techa River require on-going radioecological monitoring, management and regulatory supervision.
TL;DR: This paper considers a particular case study in which the dredging of non-hazardous sediment in the United Kingdom near a now decommissioned nuclear power station raised substantial public concern about radiological exposure, at a significant cost disproportionate to the level of radiological risk.
Abstract: The ALARA (an acronym for 'as low as reasonably achievable') principle, keeping the likelihood of incurring exposure, the number of people exposed and the magnitude of their individual doses 'as low as reasonably achievable, taking into account economic and societal factors', is at the core of radiation protection. For many decades the principle has been an area of continuous development, with recent work highlighting the importance of engaging not only with the decision-makers in the ALARA process but all stakeholders who may incur an exposure. This paper considers a particular case study in which the dredging of non-hazardous sediment in the United Kingdom near a now decommissioned nuclear power station raised substantial public concern about radiological exposure. This turned what was a straightforward construction activity into a complex public engagement and reassurance task, at a significant cost disproportionate to the level of radiological risk. This paper highlights the key lessons learnt from the case study, including not only the importance of engaging the public as part of the ALARA process but also of considering the societal impact arising from stress and concerns if misinformation is allowed to promulgate. A discussion is included on the need to underpin any engagement with a clear plan, including pre-engagement, implementation and reinforcement of messages. In addition, the role of the radiation protection professional is considered in ensuring that all stakeholders are informed, so that ultimately they can come to their own decision on what is safe.
TL;DR: The results showed that the CR-39 detectors are capable of providing high lateral resolution of carbon ion at different depths and can be used for measuring both the particle flux and its spatial distribution of carbon ions.
Abstract: The motivation of this study was to explore a new method to test the particle spatial distribution for a therapeutic carbon beam. The CR-39 plastic nuclear track detectors (PNTD) were irradiated to a 276.5 MeV/u mono-energy carbon beam at the heavy ion facility in SPHIC (Shanghai Proton and Heavy Ion Center). The spatial distribution of primary carbon beam and secondary fragments in a water phantom were systematically analyzed both in transverse direction (perpendicular to the projection direction of primary beam) and at different depths in longitudinal direction (along the projection direction of primary beam) with the measured tracks on the CR-39 detectors. Meanwhile, the theoretically spatial distribution and linear energy transfer (LET) spectra of primary beam and secondary fragments were calculated using the Monte Carlo toolkit Geant4. The results showed that the CR-39 detectors are capable to provide high lateral resolution of carbon ion at different depths. In the range of primary carbon beam, the beam width simulated with MC is in good agreement with that of experimental measurement. The track size registered in the CR-39 has a good correlation with the particle LET. These findings indicate that the CR-39 can be used for measuring both the particle flux and its spatial distribution of carbon ions.
TL;DR: In this article, a comparison of novel pregnant model phantoms with a handmade phantom in terms of shape and radiation measurement points was made to determine which model is more suitable for measuring the foetal radiation dose during x-ray examinations.
Abstract: This study presents a comparison of novel pregnant model phantoms with a handmade phantom in terms of shape and radiation measurement points to determine which model is more suitable for measuring the foetal radiation dose during x-ray examinations. Novel pregnant model phantoms were constructed using an anthropomorphic phantom in combination with two differently-sized custom-made abdomen phantoms simulating pregnancy, which were constructed from a polyurethane resin. The size and shape of the polyurethane resin were designed based on abdominal sizes and shapes collected from the computed tomography examinations at 18 pregnant patients of one hospital. The handmade pregnant model phantom was constructed using an anthropomorphic phantom and a beach ball containing water. Compared with the handmade phantom, there were additional dose measurement points on the novel pregnant model phantoms. Our model phantoms improved upon the handmade phantom in terms of shape and radiation measurement points. We produced pregnant model phantoms that simulated the shapes and sizes of actual patients for the first time.
TL;DR: In this article, animal models, essential for determining MCM efficacy, were developed and validated to assess organ-specific, potentially lethal, radiation effects against the gastrointestinal (GI) and hematopoietic acute radiation syndrome (H-ARS), and radiation-induced delayed effects to lung and associated comorbidities of prolonged immune suppression, GI, kidney and heart injury.
Abstract: Recent advances in medical countermeasures (MCMs) has been dependent on the Food and Drug Administration (FDA) animal rule (AR) and the final guidance document provided for industry on product development. The criteria outlined therein establish the path for approval under the AR. The guidance document, along with the funding and requirements from the federal agencies provided the basic considerations for animal model development in assessing radiation effects and efficacy against the potential lethal effects of acute radiation injury and the delayed effects of acute exposure. Animal models, essential for determining MCM efficacy, were developed and validated to assess organ-specific, potentially lethal, radiation effects against the gastrointestinal (GI) and hematopoietic acute radiation syndrome (H-ARS), and radiation-induced delayed effects to lung and associated comorbidities of prolonged immune suppression, GI, kidney and heart injury. Partial-body irradiation models where marginal bone marrow was spared resulted in the ability to evaluate the concomitant evolution of multiple organ injury in the acute and delayed effects in survivors of acute radiation exposure. There are no MCMs for prophylaxis against the major sequelae of the ARS or the delayed effects of acute exposure. Also lacking are MCMs that will mitigate the GI ARS consequent to potentially lethal exposure from a terrorist event or major radiation accident. Additionally, the gap in countermeasures for prophylaxis may extend to mixed neutron/gamma radiation if current modelling predicts prompt exposure from an improvised nuclear device. However, progress in the field of MCM development has been made due to federal and corporate funding, clarification of the critical criteria for efficacy within the FDA AR and the concomitant development and validation of additional animal models. These models provided for a strategic and tactical approach to determine radiation effects and MCM efficacy.
TL;DR: In this article, the ICRU recommended operational quantities for external radiation exposure were used for lens of the eye dosimetry, and the use of absorbed dose instead of dose equivalent has been selected as the appropriate operational quantity since deterministic (i.e. non-stochastic) effects are of primary importance for the lens.
Abstract: The International Commission on Radiation Units and Measurements (ICRU) Report Number 95 (2020 Operational quantities for external radiation exposureICRU Rep. 95 J. ICRU20) recommends new definitions ffor operational quantities as estimators of the International Commission on Radiological Protection radiation protection quantities. As part of this report, dose coefficients for neutron fluences are included for energies from 10-9-50 MeV. For lens of the eye dosimetry, several changes in the ICRU recommended quantities are of particular interest. First, an updated eye model is used that includes segmentation of the sensitive lens region. In addition, the use of absorbed dose instead of dose equivalent has been selected as the appropriate operational quantity since deterministic (i.e. non-stochastic) effects are of primary importance for the lens of the eye. The ICRU report also addresses computational parameters, such as absorbed dose tally volumes, depths, source areas and source rotational angles. In this work, neutron dose coefficients calculated for the lens of the eye in support of the ICRU report are presented. Dose coefficients for mono-energetic neutrons and reference neutron spectra are presented. The source is a parallel beam, and the mono-energetic dose coefficients are provided for rotational angles with respect to the front face of the head ranging from 0°-90°. In addition, monoenergetic dose coefficients for the parallel beam incident on the back of the head (180°) and for a rotational source geometry where the head is irradiated from all angles are reported. For all scenarios, absorbed doses to the complete lens and the sensitive volume of each eye were calculated. Eye lens absorbed dose coefficients,Dp,slab(3,0)/Φ, were also calculated in an ICRU tissue slab phantom at a depth of 3 mm for a parallel beam irradiating the slab perpendicular to the front face, and these results are compared to the values determined using the eye phantom.
TL;DR: Assessment of planar MGDs across Scotland and set DRLs based on data collected from all screening and symptomatic units across Scotland, considering craniocaudal and OB views and a wider range of CBTs show that use of different CBT ranges and inclusion of CC views increases the number of images included in dose audit data analysis from approximately 12%–92%, which is substantially more representative of the population.
Abstract: Optimisation must be carried out on all medical radiological units to ensure doses are as low as reasonably practicable, consistent with the intended purpose. To achieve this, population doses must be estimated and diagnostic reference levels (DRLs) set. For mammography examinations, mean glandular doses (MGDs) are calculated for this purpose. The average MGD per unit is compared to the national mammography DRL, which is applicable to compressed breast thicknesses (CBTs) of 50-60 mm for oblique (OB) views only and set using data from screening units. It is the purpose of this work to assess planar MGDs across Scotland and set DRLs based on data collected from all screening and symptomatic units across Scotland, considering craniocaudal (CC) and OB views and a wider range of CBTs. Data from the most recent dose audit (spanning 2015-2017) for 67 mammography x-ray units were collated and analysed (26 195 images). No large differences between MGD of CC and OB views were found when considering specific CBT ranges (median difference 2.6%). There was, however, a significant difference between screening and symptomatic data (19%). As expected, MGD increased with CBT and there were significant differences in MGD between manufacturers. From the data analysed, Scottish DRLs were set based on 95th percentile values for digital mammography units for three CBT ranges (30-49, 50-60 and 61-80 mm): 1.3, 1.8 and 2.6 mGy respectively. These values consider OB and CC views collectively. Fifth percentile values are quoted to highlight units at greater risk of insufficient image quality. These MGD values, together with image quality assessments, will facilitate optimisation across Scotland. Results show that use of different CBT ranges and inclusion of CC views increases the number of images included in dose audit data analysis from approximately 12%-92%, which is substantially more representative of the population.
TL;DR: The results present the first-time data on the national typical values of DRL quantities for the CT part of most common PET-CT procedures in Slovenia, which are within the DRL values established in some other countries.
Abstract: The aim was to determine typical values of diagnostic reference level (DRL) quantities for the computed tomography (CT) part of the most common positron emission tomography-computed tomography (PET-CT) procedures in Slovenia. The most common PET-CT procedures were identified, and data collated for 565 patients imaged in all three PET-CT units in Slovenia during a time span of 11 months. As the number of facilities is too low to establish national DRLs, we followed ICRP recommendations and determined typical values of DRL quantities as the median values of the pooled set of data. Mean, median, and standard deviation of CT dose index (CTDIvol) and total dose length product (DLP) for the CT part of the most common PET-CT procedures were determined for pooled data as well as for each PET-CT unit. The data were compared between all three units to identify possible outliers that would likely benefit from optimization. Three most common CT protocols covering approximately 2/3 of all PET-CT imaging performed in Slovenia were considered: from the base of the cranium to the middle of the femur, from the top of the head to the middle of the femur, and for the whole-body PET-CT. The established typical values in terms of total DLP were 295, 359, and 676 mGyċcm, respectively; and in terms of CTDIvol3.05, 3.22, and 3.60 mGy, respectively. Comparing the data between all three units showed significantly higher (p< 0.001) patient doses on one unit, indicating a need for optimization. The results present the first-time data on the national typical values of DRL quantities for the CT part of most common PET-CT procedures in Slovenia. While the determined typical values are within the DRL values established in some other countries, significant differences were found between the individual units included in the study.
TL;DR: In this paper, a review of the use of molecular protein or gene expression (mRNA) marker for early (1-3 day after irradiation), high-throughput and point-of-care diagnosis of acute radiation syndrome (ARS) in radiological or nuclear scenarios is presented.
Abstract: Radiation-induced biological changes occurring within hours and days after irradiation can be potentially used for either exposure reconstruction (retrospective dosimetry) or the prediction of consecutively occurring acute or chronic health effects. The advantage of molecular protein or gene expression (mRNA) marker lies in their capability for early (1-3 day after irradiation), high-throughput and point-of-care diagnosis, required for the prediction of the acute radiation syndrome (ARS) in radiological or nuclear scenarios. These molecular marker in most cases respond differently regarding exposure characteristics such as e.g. radiation quality, dose, dose rate and most importantly over time. Changes over time are in particular challenging and demand certain strategies to deal with. With this review, we provide an overview and will focus on already identified and used mRNA gene expression and protein markers of the peripheral blood related to the ARS. These molecules are examined in light of "ideal" characteristics of a biomarkers (e.g. easy accessible, early response, signal persistency) and the validation degree. Finally, we present strategies on the use of these markers considering challenges as their variation over time and future developments regarding e.g. origin of samples, point of care and high-throughput diagnosis.
TL;DR: In this paper, an inter-comparison exercise among individual monitoring services (IMSs) on passive whole-body dosimetry is performed in terms of both the existing operational dose quantityHp(10) and its proposed replacementHp, to allow an evaluation of the actions that may be necessary to adapt dosimetric systems to the proposed quantity.
Abstract: The new operational dosimetric quantities framework, proposed in the ICRU95 report, has stimulated the scientific community to start investigations that aim to assess its impact on radiation protection practices. As part of this effort, the present study describes an inter-comparison exercise among individual monitoring services (IMSs) on passive whole-body dosimetry. The inter-comparison is performed in terms of both the existing operational dose quantityHp(10)and its proposed replacementHp, to allow an evaluation of the actions that may be necessary to adapt dosimetry systems to the proposed quantity. For two of the tested IMSs, simple modifications to the detector response function, or the dose calculation algorithm, were sufficient to obtain results within acceptable limits. However, these approaches are not sufficient to give a level of performance comparable to that achieved in terms ofHp(10). This may require a modification to dosemeter design.
TL;DR: In this paper, the authors extended the ICRP model to the South Korean population, whose dietary iodine intake is much higher than the global mean, and selected three transfer coefficients as targets for Korean-specific values: thyroidal uptake rate, hormonal secretion rate, and leakage rate of thyroidal organic iodine as inorganic iodide.
Abstract: The International Commission on Radiological Protection (ICRP) recently adopted a detailed biokinetic model for systemic iodine with reference transfer coefficients based on typical worldwide dietary intakes of stable iodine. The regional data provided demonstrate that the ICRP reference thyroidal biokinetics may differ substantially across regions with atypically low or high dietary intakes of stable iodine. Importantly, the design of the ICRP model facilitates modifications of reference thyroidal kinetics based on regional dietary iodine intake. The present study extended the ICRP model to the South Korean population, whose dietary iodine intake is much higher than the global mean. The following three transfer coefficients were selected as targets for Korean-specific values: thyroidal uptake rate (λ1), hormonal secretion rate (λ4) and leakage rate of thyroidal organic iodine as inorganic iodide (λ5). The Korean-specific values forλ1,λ4andλ5were determined to be 4.48, 0.0086 and 0.0171 d-1, respectively, to yield the measurements of thyroidal iodine and physiological status of Korean adults. The determinedλ1andλ5values differed noticeably from the ICRP values, whereas theλ4value was comparable to that of the ICRP. Compared with the ICRP reference model, the Korean model, in which the Korean-specific transfer coefficients were adopted, predicted noticeably lower thyroidal uptake and faster decrease of thyroidal iodine. In addition, the predicted cumulative activities of radioiodine in the thyroid were substantially lower (40-80%) than those predicted by the ICRP model. The Korean model developed in this study demonstrates that the iodine biokinetics for Koreans (i.e. a population with a high iodine consumption) obviously differ from the prediction of the ICRP model. Hence, the Korean model may serve to improve the accuracy of thyroid dose estimation for Koreans and will lead to practical changes in matters concerned with radiological protection.