Implementation of the 1990 recommendations of ICRP in the countries of the European community

The International Commission on Radiological Protection (ICRP) has published new Recommendations in ICRP Publication 60. These 1990 Recommendations provide a System of Radiological Protection that takes account of the most recent information on the effects on health of exposure to ionising radiation and trends in the setting of safety standards. Within the European Community the Recommendations fo the ICRP are implemented through a Euratom Directive which is binding on member states, a draft of which has been accepted by the Article 31 Group and must eventually be ratified by the Council of Ministers. It is expected that the new directive will broadly endorse the principles of protection given in the 1990 Recommendations together with the dose limits for both workers and members of the public. There are likely to be some modifications to the 1990 Recommendations that are mainly related to their practical application. As it will be some time before the directive is incorporated into national regulations, a number of member states have taken independent initiatives. The development of dose constraints for occupational, medical and public exposure is being seen by national organisations in many countries as a significant new approach to improving standards of radiation protection.     

Validation of a system of models for plutonium decorporation therapy

A recently proposed system of models for plutonium decorporation (SPD) was developed using data from an individual occupationally exposed to plutonium via a wound [from United States Transuranium and Uranium Registries (USTUR) Case 0212]. The present study evaluated the SPD using chelation treatment data, urine measurements, and post-mortem plutonium activities in the skeleton and liver from USTUR Case 0269. This individual was occupationally exposed to moderately soluble plutonium via inhalation and extensively treated with chelating agents. The SPD was linked to the International Commission on Radiological Protection (ICRP) Publication 66 Human Respiratory Tract Model (HRTM) and the ICRP Publication 30 Gastrointestinal Tract model to evaluate the goodness-of-fit to the urinary excretion data and the predictions of post-mortem plutonium retention in the skeleton and liver. The goodness-of-fit was also evaluated when the SPD was linked to the ICRP Publication 130 HRTM and the ICRP Publication 100 Human Alimentary Tract Model. The present study showed that the proposed SPD was useful for fitting the entire, chelation-affected and non-affected, urine bioassay data, and for predicting the post-mortem plutonium retention in the skeleton and liver at time of death, 38.5 years after the accident. The results of this work are consistent with the conclusion that Ca-EDTA is less effective than Ca-DTPA for enhancing urinary excretion of plutonium.

     

Dose limits for occupational exposure to ionising radiation and genotoxic carcinogens: a German perspective

This paper summarises the view of the German Commission on Radiological Protection (“Strahlenschutzkommission”, SSK) on the rationale behind the currently valid dose limits and dose constraints for workers recommended by the International Commission on Radiological Protection (ICRP). The paper includes a discussion of the reasoning behind current dose limits followed by a discussion of the detriment used by ICRP as a measure for stochastic health effects. Studies on radiation-induced cancer are reviewed because this endpoint represents the most important contribution to detriment. Recent findings on radiation-induced circulatory disease that are currently not included in detriment calculation are also reviewed. It appeared that for detriment calculations the contribution of circulatory diseases plays only a secondary role, although the uncertainties involved in their risk estimates are considerable. These discussions are complemented by a review of the procedures currently in use in Germany, or in discussion elsewhere, to define limits for genotoxic carcinogens. To put these concepts in perspective, actual occupational radiation exposures are exemplified with data from Germany, for the year 2012, and regulations in Germany are compared to the recommendations issued by ICRP. Conclusions include, among others, considerations on radiation protection concepts currently in use and recommendations of the SSK on the limitation of annual effective dose and effective dose cumulated over a whole working life.     

Organ and detriment-weighted dose rate coefficients for exposure to radionuclide-contaminated soil considering body morphometries that differ from reference conditions: adults and children

Radiation and Environmental Biophysics - The system of protection established by the International Commission on Radiological Protection (ICRP) provides a robust framework for ionizing radiation...     

Metabolic model and dosimetric data for copper

A metabolic model for copper is derived and presented in the context of the International Commission on Radiological Protection (ICRP) dosimetry models for the lungs and gastrointestinal tract. Research sponsored by the Energy Research and Development Administration under contract with Union Carbide Corporation.     

Non-stochastic effects: compatibility with present ICRP recommendations

The present recommendations of the ICRP (International Commission on Radiological Protection) are almost entirely based on 'stochastic effects' of ionizing radiation, i.e. cancer induction and heritable effects. In a recent report the compatibility of present recommendations with non-stochastic effects has been considered. The present paper is a summary of these findings.     

Monte Carlo simulation of the dose distribution of ICRP adult reference computational phantoms for acquisitions with a 320 detector-row cone-beam CT scanner

PurposeThe purpose of this study was to develop and validate a Monte Carlo (MC) simulation tool for patient dose assessment for a 320 detector-row CT scanner, based on the recommendations of International Commission on Radiological Protection (ICRP). Additionally, the simulation was applied on four clinical acquisition protocols, with and without automatic tube current modulation (TCM).MethodsThe MC simulation was based on EGS4 code and was developed specifically for a 320 detector-row cone-beam CT scanner. The ICRP adult reference phantoms were used as patient models. Dose measurements were performed free-in-air and also in four CTDI phantoms: 150 mm and 350 mm long CT head and CT body phantoms. The MC program was validated by comparing simulations results with these actual measurements acquired under the same conditions. The measurements agreed with the simulations across all conditions within 5%. Patient dose assessment was performed for four clinical axial acquisitions using the ICRP adult reference phantoms, one of them using TCM.ResultsThe results were nearly always lower than those obtained from other dose calculator tools or published in other studies, which were obtained using mathematical phantoms in different CT systems. For the protocol with TCM organ doses were reduced by between 28 and 36%, compared to the results obtained using a fixed mA value.ConclusionsThe developed simulation program provides a useful tool for assessing doses in a 320 detector-row cone-beam CT scanner using ICRP adult reference computational phantoms and is ready to be applied to more complex protocols.     

Radiation protection: the NCRP guidelines and some considerations for the future.

The National Council on Radiation Protection and Measurements (NCRP) in the USA and the International Commission on Radiological Protection (ICRP), worldwide, were formed about 1928 and have since made recommendations on appropriate levels of protection from ionizing radiation for workers and for the public. These recommendations and much of the guidance provided by these organizations have usually been adopted by regulatory bodies around the world. In the case of the NCRP, the levels have fallen from 0.1 roentgen per day in 1934 to the current 5 rem per year (a factor of about 5). The present levels recommended by both the ICRP and the NCRP correspond to reasonable levels of risk where the risks of harm from ionizing radiation are compared with the hazards of other, commonly regarded, as safe, industries. Some considerations for the future in radiation protection include trends in exposure levels (generally downward for the average exposure to workers) and improvements in risk estimation; questions of lifetime limits, de minimis levels, and partial body exposures; plus problems of high LET radiations, acceptability of risk, synergisms, and risk systems for protection.     

Ecological and radiological hazards due to natural radioactivity and heavy metals in soils of some selected mining sites in Nigeria

Abstract

In this study, the radiological and pollution risks associated with mining of minerals in Nigeria were assessed. Soil samples were collected from a total of 30 illegal mining sites, 10 each from gold, coal and tin mining sites. Thirty soil samples were also collected from unpolluted sites around the mine works. The activity concentrations of the natural radionuclides in the samples were determined using a well calibrated Sodium Iodide Na(Tl) detector. The concentration of Pb, Zn, Cu, Mn, Cr, Cd, Ni and As were determined using an energy dispersive X-ray fluorescence (EDXRF) analyses. The results showed elevated levels of the radionuclides and heavy metals in the mining sites compared to the unpolluted soils. The average outdoor annual effective dose (OAED) obtained were lower than the International Commission on Radiological Protection (ICRP) recommended limit of 1 mSv/y. The results of the geo-accumulation index however showed that the soils of the study areas were strongly contaminated with Pb, Cd and As.     

Mayak worker study: an improved biokinetic model for reconstructing doses from internally deposited plutonium

The plutonium production facility known as the Mayak Production Association was put into operation in June 1948. A high incidence of cancer in the Mayak workers has been related to the level of exposure to plutonium, but uncertainties in tissue doses have hampered development of dose-risk relationships. As part of an effort to improve dose estimates for these workers, the systemic biokinetic model for plutonium currently recommended by the International Commission on Radiological Protection (ICRP) has been modified to reflect recently developed data and facilitate interpretation of case-specific information. This paper describes the proposed model and discusses its implications for dose reconstruction for the Mayak workers.     

<Superscript>131</Superscript>I age-dependent inhalation dose in Southern Poland from Fukushima accident

A general method for calculating doses absorbed from isotopes released in nuclear accidents is presented. As an example, this method was used to calculate doses for inhabitants of Southern Poland due to inhalation of ¹³¹I released due to the Fukushima nuclear plant accident. ¹³¹I activity measurements in the air of that region provided the basis for the study. The proposed model is based on a complex biokinetic model for iodine merging the Leggett model developed in 2010 with the human respiratory tract and gastrointestinal tract models recommended by the International Commission on Radiological Protection (ICRP). This model is described here, and it is demonstrated that resulting dose estimates are consistent with those obtained using the ICRP methodology. Using the developed model, total doses were calculated for six age groups of both genders, for gaseous and aerosol fractions alike. The committed effective dose, H ₅₀, for an adult man reached 16 nSv, which is lower than 0.001% of the background dose. The dose for the thyroid of an adult reached 0.33 μSv, which corresponds to circa 0.0007% of the dose to the population of Southern Poland after the Chernobyl nuclear plant accident.     

Principal inferences from studies of radiobiological effects for radiation protection purposes

The most recent Recommendations (Publication 103) issued by the International Commission for Radiological Protection (ICRP) are based on the data that have been published since 1990 up to now. The basic task of the ICRP Committee 1 was to formulate the key implications of studies on radiobiological effects for the purposes of radiological protection. Presented in the paper are the new achievements in the field of biology, radiobiology and radiation epidemiology which were taken into account by the ICRP in the process of Publication 103 preparation. The Recommendations provide present-day values of weighting factors for radiation exposure and tissue weighting factors, as well as radiation detriment and radiogenic risk factors for cancer and genetic diseases. Also considered are tissue reactions to radiation exposure, consequences of in utero exposure and the risks of developing non-cancer diseases for exposed individuals. It should be noted that the key inferences and recommendations are to a considerable degree related to biological effects accounted for by acute and chronic exposure to ionizing radiation in the range of small doses (up to 100 mSv).     

Effective dose from radiation exposure in medicine: Past,present, and future

Effective dose (E) has been developed by the International Commission on Radiological Protection (ICRP) as a dose quantity with a link to risks of health detriment, mainly cancer. It is based on reference phantoms representing average individuals, but this is often forgotten in its application to medical exposures, for which its use sometimes goes beyond the intended purpose. There has been much debate about issues involved in the use of E in medicine and ICRP is preparing a publication with more information on this application. This article aims to describe the development of E and explain how it should be used in medicine. It discusses some of the issues that arise when E is applied to medical exposures and provides information on how its use might evolve in the future. The article concludes with responses to some frequently asked questions about uses of E that are in line with the forthcoming ICRP publication. The main use of E in medicine is in meaningful comparison of doses from different types of procedure not possible with measurable dose quantities. However, it can be used, with appropriate care, as a measure of possible cancer risks. When considering E to individual patients, it is important to note that the dose received will differ from that assessed for reference phantoms, and the risk per Sv is likely to be greater on average in children and less in older adults. Newer techniques allow the calculation of patient-specific E which should be distinguished from the reference quantity.     

Model-derived dose rates per unit concentration of radon in air in a generic plant geometry

A model for the derivation of dose rates per unit radon concentration in plants was developed in line with the activities of a Task Group of the International Commission on Radiological Protection (ICRP), aimed at developing more realistic dosimetry for non-human biota. The model considers interception of the unattached and attached fractions of the airborne radon daughters by plant stomata, diffusion of radon gas through stomata, permeation through the plant’s epidermis and translocation of deposited activity to plant interior. The endpoint of the model is the derivation of dose conversion coefficients relative to radon gas concentration at ground level. The model predicts that the main contributor to dose is deposition of ²¹⁴Po α-activity on the plant surface and that diffusion of radon daughters through the stomata is of relatively minor importance; hence, daily variations have a small effect on total dose.     

Polonium-210 Absorption in Rats: Effects of Biological Modification

CALCULATIONS of maximum permissible body burdens of polonium-210 for radiation workers and the general public made by the International Commission on Radiological Protection (ICRP) assume 0.06 as the fraction going from the gastrointestinal tract to blood¹. This estimate is based on the work of Delia Rosa et al.², in which freshly neutralized polonium chloride solution was given orally to rats by stomach intubation (gavage). Excretion functions and tissue retention were measured and used to calculate the transfer of polonium across the gut. Hill³ and Kauranen and Miettinen⁴, who studied the transfer of Po along the lichen-reindeer or caribou-man food chain, suggested that the ²¹⁰Po found in the soft tissues of herbivores may be organically bound and therefore readily available to humans. Their data indicated that the ²¹⁰Po ingested from reindeer meat was from five to twenty-five times more available than predicted from the transfer values adopted by the ICRP. Experiments reported here indicate that polonium secreted in the milk of a goat which had been given an acute oral dose of PoO₂ is absorbed across the gut of rats in concentrations approximately twenty times greater than that absorbed when rats are fed PoO₂ or PoCl₄ in drinking water. These results are at least partial verification of the greater availability of ²¹⁰Po through biological modification as estimated by Hill.     

Comparison of neutron organ and effective dose coefficients for PIMAL stylized phantom in bent postures in standard irradiation geometries

Neutron dose coefficients for standard irradiation geometries have been reported in International Commission on Radiological Protection (ICRP) Publication 116 for the ICRP Publication 110 adult reference phantoms. In the present work, organ and effective dose coefficients have been calculated for a receptor in both upright and articulated (bent) postures representing more realistic working postures exposed to a mono-energetic neutron radiation field. This work builds upon prior work by Dewji and co-workers comparing upright and bent postures for exposure to mono-energetic photon fields. Simulations were conducted using the Oak Ridge National Laboratory’s articulated stylized adult phantom, “Phantom wIth Moving Arms and Legs” (PIMAL) software package, and the Monte Carlo N-Particle (MCNP) version 6.1.1 radiation transport code. Organ doses were compared for the upright and bent (45° and 90°) phantom postures for neutron energies ranging from 1 × 10^??9 to 20 MeV for the ICRP Publication 116 external exposure geometries—antero-posterior (AP), postero-anterior (PA), and left and right lateral (LLAT, RLAT). Using both male and female phantoms, effective dose coefficients were computed using ICRP Publication 103 methodology. The resulting coefficients for articulated phantoms were compared to those of the upright phantom. Computed organ and effective dose coefficients are discussed as a function of neutron energy, phantom posture, and source irradiation geometry. For example, it is shown here that for the AP and PA irradiation geometries, the differences in the organ coefficients between the upright and bent posture become more pronounced with increasing bending angle. In the AP geometry, the brain dose coefficients are expectedly higher in the bent postures than in the upright posture, while all other organs have lower dose coefficients, with the thyroid showing the greatest difference. Overall, the effective dose estimated for the upright phantom is more conservative than that for the articulated phantom, which may have ramifications in the estimation or reconstruction of radiation doses.     

Human biokinetics of strontium—part II: Final data evaluation of intestinal absorption and urinary excretion of strontium in human subjects after stable tracer administration

Fractional intestinal absorption (f ₁ value) and urinary excretion of strontium in healthy human volunteers has been measured by simultaneous oral and intravenous administration of the stable isotopes ⁸⁶Sr and ⁸⁴Sr using the double-isotope method. Final evaluation of the complete data set confirmed that ingestion of different foodstuff and nutritional factors could influence the fractional gut uptake of strontium. In some cases, significant deviations from the f ₁ value adopted by the International Commission on Radiological Protection (ICRP) were found. The arithmetic mean (± standard deviation) of the f ₁ values of all experiments performed was determined to be 0.46 (± 0.24). The probability distribution function of the f ₁ values is represented by a lognormal curve with a geometric mean of 0.38 and a geometric standard deviation of 2.06. Urinary excretion in all subjects varied depending on the administered foodstuff in a wide range and differs from the ICRP model, up to 2 days after tracer administration. No age or gender dependence of the absorbed strontium fraction and of the urinary excretion of strontium after an oral load was found.     

Assessment of radon equilibrium factor from distribution parameters of simultaneous radon and radon progeny measurements

In Canada, a radon and radon progeny survey was carried out in the 1970s in 19 cities. To the authors’ knowledge, this is the only large survey of simultaneous radon and radon progeny measurements up to the present time. However, the survey was carried out for the purpose of establishing geographic variation of radon and radon progeny; therefore, radon equilibrium factors, F, were not assessed at that time. From the summary results of this large simultaneous radon and radon progeny survey, the characteristics of radon equilibrium factor were assessed. The average F factor assessed from this survey in 12,576 houses is 0.54. The current assessment may indicate that the typical F value of 0.4 recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), and the International Commission on Radiological Protection (ICRP) could lead to a downward bias in the estimation of radon doses to the lung.     

National survey to set diagnostic reference levels in nuclear medicine single photon emission imaging in Croatia

PurposeIn order to introduce the concept of diagnostic reference levels (DRLs) in the national nuclear medicine practice a survey was proposed and completed through all nuclear medicine departments in Croatia. An additional aim was to increase the awareness of importance and full implementation of a comprehensive quality program that includes devices used in the nuclear medicine chain.MethodsData were collected for more than 30 nuclear medicine single photon emission procedures. National DRLs (NDRLs) as administered activity and also as administered activity per unit mass were calculated in accordance to International Commission on Radiological Protection (ICRP) recommendations. Additionally, effective doses were estimated using conversion factors published by the ICRP.ResultsNDRLs for nuclear medicine single photon emission procedures were proposed. For procedures performed in only one department typical values were presented as reference. Effective doses related to applied radiopharmaceuticals were calculated to estimate radiation risk related to respective nuclear medicine procedure in more detail.ConclusionThis work presents results of the first national survey on DRLs of nuclear medicine single photon emission procedures and proposes reliable NDRLs that represent an actual status of nuclear medicine practice in Croatia. Results have motivated departments to introduce and set their own typical values to be used, as one of the tools, for further optimization process. One of the drawbacks of the DRL concept in nuclear medicine is the lack of the image quality parameters involved. For this reason, a quantity that considers both radiation protection and image quality should be introduced.     

Transfer parameters for ICRP reference animals and plants collected from a forest ecosystem

The International Commission on Radiological Protection (ICRP) have suggested the identification of a series of terrestrial, marine and freshwater sites from which samples of each Reference animal and plant (RAP) could be systematically collected and analysed. We describe the first such study in which six of the eight terrestrial RAPs, and associated soil samples, were collected from a site located in a managed coniferous forestry plantation in north-west England. Adult life stages of species representing six of the terrestrial RAPs (Wild grass, Pine tree, Deer, Rat, Earthworm and Bee) were sampled and analysed to determine concentrations of 60 elements and gamma-emitting radionuclides. The resultant data have been used to derive concentration ratios (CR_wo-soil) relating element/radionuclide concentrations in the RAPs to those in soil. This paper presents the first-reported transfer parameters for a number of the RAP–element combinations. Where possible, the derived CR_wo-soil values are compared with the ICRPs-recommended values and any appreciable differences discussed.