Showing papers in "Annals of The Icrp in 2012"

ICRP PUBLICATION 118: ICRP Statement on Tissue Reactions and Early and Late Effects of Radiation in Normal Tissues and Organs – Threshold Doses for Tissue Reactions in a Radiation Protection Context

Abstract: This report provides a review of early and late effects of radiation in normal tissues and organs with respect to radiation protection. It was instigated following a recommendation in Publication 103 (ICRP, 2007), and it provides updated estimates of 'practical' threshold doses for tissue injury defined at the level of 1% incidence. Estimates are given for morbidity and mortality endpoints in all organ systems following acute, fractionated, or chronic exposure. The organ systems comprise the haematopoietic, immune, reproductive, circulatory, respiratory, musculoskeletal, endocrine, and nervous systems; the digestive and urinary tracts; the skin; and the eye. Particular attention is paid to circulatory disease and cataracts because of recent evidence of higher incidences of injury than expected after lower doses; hence, threshold doses appear to be lower than previously considered. This is largely because of the increasing incidences with increasing times after exposure. In the context of protection, it is the threshold doses for very long follow-up times that are the most relevant for workers and the public; for example, the atomic bomb survivors with 40-50years of follow-up. Radiotherapy data generally apply for shorter follow-up times because of competing causes of death in cancer patients, and hence the risks of radiation-induced circulatory disease at those earlier times are lower. A variety of biological response modifiers have been used to help reduce late reactions in many tissues. These include antioxidants, radical scavengers, inhibitors of apoptosis, anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, growth factors, and cytokines. In many cases, these give dose modification factors of 1.1-1.2, and in a few cases 1.5-2, indicating the potential for increasing threshold doses in known exposure cases. In contrast, there are agents that enhance radiation responses, notably other cytotoxic agents such as antimetabolites, alkylating agents, anti-angiogenic drugs, and antibiotics, as well as genetic and comorbidity factors. Most tissues show a sparing effect of dose fractionation, so that total doses for a given endpoint are higher if the dose is fractionated rather than when given as a single dose. However, for reactions manifesting very late after low total doses, particularly for cataracts and circulatory disease, it appears that the rate of dose delivery does not modify the low incidence. This implies that the injury in these cases and at these low dose levels is caused by single-hit irreparable-type events. For these two tissues, a threshold dose of 0.5Gy is proposed herein for practical purposes, irrespective of the rate of dose delivery, and future studies may elucidate this judgement further.

ICRP Publication 119: Compendium of Dose Coefficients based on ICRP Publication 60

Abstract: This report is a compilation of dose coefficients for intakes of radionuclides by workers and members of the public, and conversion coefficients for use in occupational radiological protection against external radiation from Publications 68, 72, and 74 (ICRP, 1994b, 1996a,b). It serves as a comprehensive reference for dose coefficients based on the primary radiation protection guidance given in the Publication 60 recommendations (ICRP, 1991). The coefficients tabulated in this publication will be superseded in due course by values based on the Publication 103 recommendations (ICRP, 2007).

Mechanisms and dose-response relationships for radiation-induced cardiovascular disease

Abstract: Epidemiological studies have shown a clear association between therapeutic doses of thoracic irradiation and increased risk of cardiovascular disease in long-term cancer survivors. Survivors of Hodgkin's lymphoma and childhood cancers, for example, show 2- to >7-fold increases in risk of cardiac death after total tumour doses of 30–40 Gy, given in 2-Gy fractions. The risk of cardiac mortality increases linearly with dose, although there are large uncertainties for mean cardiac doses <5 Gy. Experimental studies show that doses of ⩾2 Gy induce the expression of inflammatory and thrombotic molecules in endothelial cells. In the heart, this causes progressive loss of capillaries and eventually leads to reduced perfusion, myocardial cell death, and fibrosis. In large arteries, doses of ⩾8 Gy, combined with elevated cholesterol, initiates atherosclerosis and predisposes to the formation of inflammatory, unstable lesions, which are prone to rupture and may cause a fatal heart attack or stroke. In contrast, doses...

We can do better than effective dose for estimating or comparing low-dose radiation risks:

Abstract: The effective dose concept was designed to compare the generic risks of exposure to different radiation fields. More commonly these days, it is used to estimate or compare radiation-induced cancer risks. For various reasons, effective dose represents flawed science: for instance, the tissue-specific weighting factors used to calculate effective dose are a subjective mix of different endpoints; and the marked and differing age and gender dependencies for different health detriment endpoints are not taken into account. This paper suggests that effective dose could be replaced with a new quantity, ‘effective risk’, which, like effective dose, is a weighted sum of equivalent doses to different tissues. Unlike effective dose, where the tissue-dependent weighting factors are a set of generic, subjective committee-defined numbers, the weighting factors for effective risk are simply evaluated tissue-specific lifetime cancer risks per unit equivalent dose. Effective risk, which has the potential to be age and gender specific if desired, would perform the same comparative role as effective dose, be just as easy to estimate, be less prone to misuse, be more directly understandable, and would be based on solid science. An added major advantage is that it gives the users some feel for the actual numerical values of the radiation risks they are trying to control.

Effective dose and risks from medical x-ray procedures

Abstract: The radiation risks from a range of medical x-ray examinations (radiography, fluoroscopy, and computed tomography) were assessed as a function of the age and sex of the patient using risk models described in Publication 103 (ICRP, 2007) and UNSCEAR (2006, Annex A). Such estimates of risk based on typical organ doses were compared with those derived from effective doses using the International Commission on Radiological Protection's nominal risk coefficients. Methodologically similar but not identical dose and risk calculations were performed independently at the Institute of Radiation Hygiene (Russia) and the Health Protection Agency (UK), and led to similar conclusions. The radiogenic risk of stochastic health effects following various x-ray procedures varied significantly with the patient's age and sex, but to differing degrees depending on which body organs were irradiated. In general, the risks of radiation-induced stochastic health effects in children are estimated to be higher (by a factor of ≤ 4) than in adults, and risks in senior patients are lower by a factor of ≥ 10 relative to younger people. If risks are assessed on the basis of effective dose, they are underestimated for children of both sexes by a factor of ≤ 4. This approach overestimates risks by a factor of ≤ 3 for adults and about an order of magnitude for senior patients. The significant sex and age dependence of radiogenic risk for different cancer types is an important consideration for radiologists when planning x-ray examinations. Whereas effective dose was not intended to provide a measure of risk associated with such examinations, it may be sufficient to make simple adjustments to the nominal risk per unit effective dose to account for age and sex differences.

Independent but not isolated.

Abstract: On 8 August 2004, the International Commission on Radiological Protection (ICRP) formally began open, public consultation on what was then referred to as the draft ‘2005 Recommendations of ICRP’. As most readers will know, this was published in due course as Publication 103, ‘The 2007 Recommendations of the International Commission on Radiological Protection’ (ICRP, 2007). This was only one step in what Lars-Erik Holm, ICRP Chairman at the time of publication of the 2007 Recommendations, referred to – in the editorial to that publication – as ‘a much more open process than that used for the development of the previous recommendations’. However, it was a key step. Being managed through the ICRP website, it opened up the possibility for anyone, anywhere, with an internet connection and an interest in radiological protection, to review the draft document and submit comments directly to ICRP. Since then, ICRP has conducted 26 more public consultations on draft publications. Today, this important step is integrated into the development of most ICRP publications, the notable exceptions being those that are essentially collections of tabulated numbers, and the present publication. Public consultation was not sought on this publication because the papers contained herein are not recommendations of ICRP and do not necessarily represent the views of ICRP; they are the work of the individual authors. Formal public consultation on draft publications is but one aspect of ICRP’s efforts to become a more open and transparent organisation. Another cornerstone of these efforts is the holding of regular ICRP symposia. This is not undertaken lightly. As a registered charity with limited financial resources, ICRP cannot afford to take on the full expense of organising such large meetings. This is further complicated by ICRP not wanting to create financial barriers to participation; therefore, every effort has been made to avoid charging a substantial registration fee. Balanced with these challenges are the benefits afforded through holding regular ICRP symposia: opportunities to directly hear the views of many radiological protection professionals from around the world; and opportunities to more effectively disseminate, explain, and discuss the recommendations of ICRP. The First ICRP Symposium on the International System of Radiological Protection, or simply ICRP 2011, was held in Bethesda (Rockland) Maryland, just outside of Washington D.C., October 24–26, 2011. This was largely possible due to the financial support of several organisations with an interest in radiological protection:

Risk of lung cancer from radon exposure: contribution of recently published studies of uranium miners.

Abstract: The International Commission on Radiological Protection (ICRP) recently estimated the risk of lung cancer associated with radon exposure, and a statement was issued in ICRP Publication 115. This was based on recent epidemiological studies and the results from a joint analysis of cohorts of Czech, French, and German uranium miners, and indicated that the excess relative risk of lung cancer per unit of exposure should be expressed with consideration of chronic exposure over more than 10 years, by modelling time since median exposure, age attained or age at exposure, and taking in account, if possible, interaction between radon and tobacco. The lifetime excess absolute risk (LEAR) calculated from occupational exposure studies is close to 5 × 10(-4) per working level month (WLM) (14 × 10(-5) per hmJ/m(3)). LEAR values estimated using risk models derived from both miners and domestic exposure studies are in good agreement after accounting for factors such as sex, attained age, and exposure scenario. A sensitivity analysis highlighted the high dependence of background mortality rates on LEAR estimates. Using lung cancer rates among Euro-American males instead of the ICRP reference rates (males and females, and Euro-American and Asian populations), the estimated LEAR is close to 7 × 10(-4) per WLM (20 × 10(-5) per hm J/m(3)).

Minimising medically unwarranted computed tomography scans

Abstract: As computed tomography (CT) is such a superb diagnostic tool and individual CT risks are small, whenever a CT scan is clinically warranted, the CT benefit/risk balance is by far in the patient's favour. However, if a CT scan is not clinically warranted, this balance shifts dramatically. It is likely that at least 25% of CT scans fall into this latter category, in that they could either be replaced with alternative imaging modalities or could be avoided entirely. Use of clinical decision rules for CT usage represents a powerful approach for slowing down the increase in CT usage, because they have the potential to overcome some of the major factors that result in some CT scans being undertaken when they may not be clinically helpful.

ICRP and IAEA actions on radiation protection in computed tomography

Abstract: In 1998, the International Commission on Radiological Protection (ICRP) warned that computed tomography (CT) doses were high, and the frequency of usage was likely to increase in view of spiral CT technology that enhances patient convenience and provides high-quality diagnostic information. Two ICRP publications (Publications 87 and 102) have provided patient dose management recommendations while reviewing the technology and results of optimisations to date, and stimulated interest in patient dose management. The International Atomic Energy Agency, on the other hand, has been instrumental in assessing the state of practice at grassroots level, identifying lacunae in justification and optimisation, providing guidance to counterparts in various countries, and improving practice. The results from approximately 50 less-resourced countries for adult and paediatric CT studies have become available, and some have been published. The concerted efforts and actions by these two international organisations have contributed to better awareness and improvement of patient protection in CT in adults and children in many countries.

Effective dose from inhaled radon and its progeny.

Abstract: Currently, the International Commission on Radiological Protection (ICRP) uses the dose conversion convention to calculate effective dose per unit exposure to radon and its progeny. In a recent statement, ICRP indicated the intention that, in future, the same approach will be applied to intakes of radon and its progeny as is applied to all other radionuclides, calculating effective dose using reference biokinetic and dosimetric models, and radiation and tissue weighting factors. Effective dose coefficients will be given for reference conditions of exposure. In this paper, preliminary results of dose calculations for Rn-222 progeny are presented and compared with values obtained using the dose conversion convention. Implications for the setting of reference levels are also discussed.

Radiation biology and radiation protection.

Abstract: For protection purposes, the biological effects of radiation are separated into stochastic effects (cancer, hereditary effects) presumed to be unicellular in origin, and tissue reactions due to injury in populations of cells. The latter are deterministic effects, renamed 'tissue reactions' in the 2007 Recommendations of the International Commission on Radiological Protection because of the increasing evidence of the ability to modify responses after irradiation. Tissue reactions become manifest either early or late after doses above a threshold dose, which is the basis for recommended dose limits for avoiding such effects. Latency time before manifestation is related to cell turnover rates, and tissue proliferative and structural organisation. Threshold doses have been defined for practical purposes at 1% incidence of an effect. In general, threshold doses are lower for longer follow-up times because of the slow progression of injury before manifestation. Radiosensitive individuals in the population may contribute to low threshold doses, and in the future, threshold doses may be increased by the use of various biological response modifiers post irradiation for reducing injury. Threshold doses would be expected to be higher for fractionated or protracted doses, unless doses below the threshold dose only cause single-hit-type events that are not modified by repair/recovery phenomena, or if different mechanisms of injury are involved at low and high doses.

Effective dose: a radiation protection quantity:

Abstract: Modern radiation protection is based on the principles of justification, limitation, and optimisation. Assessment of radiation risks for individuals or groups of individuals is, however, not a primary objective of radiological protection. The implementation of the principles of limitation and optimisation requires an appropriate quantification of radiation exposure. The International Commission on Radiological Protection (ICRP) has introduced effective dose as the principal radiological protection quantity to be used for setting and controlling dose limits for stochastic effects in the regulatory context, and for the practical implementation of the optimisation principle. Effective dose is the tissue weighted sum of radiation weighted organ and tissue doses of a reference person from exposure to external irradiations and internal emitters. The specific normalised values of tissue weighting factors are defined by ICRP for individual tissues, and used as an approximate age- and sex-averaged representation of the relative contribution of each tissue to the radiation detriment of stochastic effects from whole-body low-linear energy transfer irradiations. The rounded values of tissue and radiation weighting factors are chosen by ICRP on the basis of available scientific data from radiation epidemiology and radiation biology, and they are therefore subject to adjustment as new scientific information becomes available. Effective dose is a single, risk-related dosimetric quantity, used prospectively for planning and optimisation purposes, and retrospectively for demonstrating compliance with dose limits and constraints. In practical radiation protection, it has proven to be extremely useful.

Relative biological effectiveness and radiation weighting factors in the context of animals and plants

Abstract: Radiation weighting factors have long been employed to modify absorbed dose as part of the process of evaluating radiological impact to humans. Their use represents an acknowledgement of the fundamental difference in energy deposition patterns of charged and uncharged particles, and how this can translate into varying degrees of biological impact. Weighting factors used in human radiation protection are derived from a variety of endpoints taken from in-vitro experiments that include human and animal cell lines, as well as in-vivo experiments with animals. Nonetheless, the application of radiation weighting factors in the context of dose assessment of animals and plants is not without some controversy. Specifically, radiation protection of biota has largely focused on limiting deterministic effects, such as reduced reproductive fitness. Consequently, the application of conventional stochastic-based radiation weighting factors (when used for human protection) appears inappropriate. While based on research, radiation weighting factors represent the parsing of extensive laboratory studies on relative biological effectiveness. These studies demonstrate that the magnitude of a biological effect depends not just on dose, but also on other factors including the rate at which the dose is delivered, the type and energy of the radiation delivering the dose, and, most importantly, the endpoint under consideration. This article discusses the efforts taken to develop a logical, transparent, and defensible approach to establishing radiation weighting factors for use in assessing impact to non-human biota, and the challenges found in differentiating stochastic from deterministic impacts.

NORM Management in the oil and gas industry

Abstract: It has been established that naturally occurring radioactive material (NORM) may accumulate at various locations along the oil and gas production process. Components such as wellheads, separation vessels, pumps, and other processing equipment can become contaminated with NORM, and NORM can accumulate in the form of sludge, scale, scrapings, and other waste media. This can create a potential radiation hazard to workers, the general public, and the environment if certain controls are not established. Saudi Aramco has developed NORM management guidelines, and is implementing a comprehensive strategy to address all aspects of NORM management that aim to enhance NORM monitoring; control of NORM-contaminated equipment; control of NORM waste handling and disposal; and protection, awareness, and training of workers. The benefits of shared knowledge, best practice, and experience across the oil and gas industry are seen as key to the establishment of common guidance. This paper outlines Saudi Aramco's experience in the development of a NORM management strategy, and its goals of establishing common guidance throughout the oil and gas industry.

Radiation effects: Modulating factors and risk assessment - an overview:

Abstract: Following low dose or low dose-rate exposures to ionising radiation, the principal resulting radiation-related risk is cancer. Site-specific cancer risk models have been developed that describe how the radiation-induced risk of a particular cancer type varies with the relevant tissue-specific absorbed dose of radiation. The degree of risk will also be determined by the radiation quality and the dose-rate, factors that will vary between types of radiation and cancer. Risk models also include a number of intrinsic factors that modify the radiation-related excess risk – sex, age at exposure, time since exposure, and attained age – although not all these factors enter into each site-specific model. Of some importance is how the radiation-related excess risk is transferred between populations when background incidence rates differ. For most cancer types, expert groups consider that the radiation-related excess risk in a population depends, to some extent, upon the background incidence rate, and therefore that radiation interacts with at least some of the major risk factors that determine the background risk for a person. For example, the radiation-induced risk of lung cancer depends on the degree of individual exposure to tobacco smoke, but the implicit assumption of the currently accepted risk transfer models is that interactions are a general feature of radiation-related cancer risk.

Dosimetry for Reference Animals and Plants: current state and prospects.

Abstract: The enormous diversity of non-human biota is a specific challenge when developing and applying dosimetric models for assessing exposures to flora and fauna from environmental radioactivity. Dosimetric models, adopted by the International Commission on Radiological Protection (ICRP), provide dose conversion coefficients for a large variety of biota, including the Reference Animals and Plants. The models use a number of simplified approaches, often ignoring presumably insignificant details. Simple body shapes with uniform composition and density, homogeneous internal contamination, a limited set of external radiation sources for terrestrial animals and plants, and truncation of radioactive decay chains are a few examples of simplifying assumptions underlying the dose conversion coefficients included in ICRP Publication 108. However, many specific assessment tasks require dosimetric data for non-standard species or irradiation scenarios. The further development of dosimetric models aims at the implementation of flexible choices of animals and plants, as well as of their irradiation conditions (e.g. trees); more systematic consideration of internal exposures from radionuclides concentrated in specific organs; and task-oriented choice of decay chains based on ICRP Publication 107. An extensive set of non-human dosimetric data might require specific software to facilitate fast, accurate, and flexible selection of pertinent dose conversion coefficients for specific assessment tasks.

NORM situation in non-uranium mining in China

Abstract: The Ministry of Environmental Protection in China is responsible for regulatory control on radiation protection from naturally occurring radioactive material (NORM). The natural radiation caused by human activities is a major contributor to public and occupational exposure in China. This paper introduces the first national census on pollution sources (target year 2007) in China, and describes NORM sites in Baotou, Inner Mongolia, one of the largest rare earth deposits in China. The ores are rich in radioactive elements, with a concentration of ThO2 of 0.01–0.05% and concentration of U3O8 of 0.0005–0.002%. The large amount of NORM residues is regulated and controlled. After treatment of the waste water, it is discharged into tailing ponds and then pumped directly to milling plants for re-use. The waste gas after off-dust cleaning is discharged into the environment. A substantial amount of blast furnace iron slag from the waste treatment is transformed into cement, concrete, and bricks, or used directly for highway construction. This raises a serious environmental concern. As a result, environmental radiation monitoring and assessment have been introduced recently. Regulatory control of NORM is very important in order to take effective measures to lower the dose.

Biological basis for protection of the environment.

Abstract: The approach to protection of the environment may vary considerably depending on ethical basis, methodological approach, and identification of endpoints and protective targets. The International Commission on Radiological Protection (ICRP) reviewed these issues in Publication 91, ‘A framework for assessing the impact of ionising radiation on non-human species’, published in 2003. At the same time, ICRP proposed that a possible future ICRP system addressing environmental assessment and protection would focus on biota, that the system should be effect-based so that any reasoning about adequate protection would be derived from firm understanding of harm at different exposure levels, and that the system should be based on data sets for Reference Animals and Plants. ICRP has thus chosen to approach environmental protection on the basis of biology, and further developed the approach in Publications 103, 108 and 114. This paper explores the biological basis for the ICRP system of environmental protection from the viewpoints of: the effects endpoints of concern; the hierarchy of biological organisation; adequate and appropriate protective targets; and the derivation of benchmark dose (rates) to guide protective efforts.

Radiological protection in paediatric computed tomography.

Abstract: It is well known that paediatric patients are generally at greater risk for the development of cancer per unit of radiation dose compared with adults, due both to the longer life expectancy for any harmful effects of radiation to manifest, and the fact that developing organs and tissues are more sensitive to the effects of radiation. Multiple computed tomography (CT) examinations may cumulatively involve absorbed doses to organs and tissues that can sometimes approach or exceed the levels known from epidemiological studies to significantly increase the probability of cancer development. Radiation protection strategies include rigorous justification of CT examinations and the use of imaging techniques that are non-ionising, followed by optimisation of radiation dose exposure (according to the 'as low as reasonably achievable' principle). Special consideration should be given to the availability of dose reduction technology when acquiring CT scanners. Dose reduction should be optimised by adjustment of scan parameters (such as mAs, kVp, and pitch) according to patient weight or age, region scanned, and study indication (e.g. images with greater noise should be accepted if they are of sufficient diagnostic quality). Other strategies include restricting multiphase examination protocols, avoiding overlapping of scan regions, and only scanning the area in question. Newer technologies such as tube current modulation, organ-based dose modulation, and iterative reconstruction should be used when appropriate. Attention should also be paid to optimising study quality (e.g. by image post-processing to facilitate radiological diagnoses and interpretation). Finally, improving awareness through education and advocacy, and further research in paediatric radiological protection are important to help reduce patient dose.

Application of radiological protection measures to meet different environmental protection criteria.

Abstract: The International Commission on Radiological Protection (ICRP) recognises that there is no simple or single universal definition of ‘environmental protection’, and that the concept differs from country to country and from one circumstance to another. However, there is an increasing need to be able to demonstrate that the environment is protected from radioactive substances released under authorisation for various reasons, such as for wildlife conservation requirements, or wildlife management for commercial reasons, or simply as part of pollution control. The Commission is developing the concept of Representative Organisms, which may be identified from any specific legal requirements or from more general requirements to protect local habitats or ecosystems. Such organisms may be the actual objects of protection or they may be hypothetical, depending on the objectives of the assessment. They may be similar to, or even congruent with, one or more of the Reference Animals and Plants (RAPs). Where this is not the case, attempts can be made to consider the extent to which the Representative Organisms differ from the nearest RAP in terms of known radiation effects upon it, basic biology, radiation dosimetry, and pathways of exposure. This paper discusses the practical implications of such an approach.

Accident prevention in day-to-day clinical radiation therapy practice

Abstract: Nearly 50–60% of cancer patients will undergo radiotherapy at some point in their treatment. Around 85% of the world’s population live in developing countries served by approximately 30% of the world’s radiotherapy facilities. It has been suggested that 1 megavoltage unit is required for every 500 new treatment courses per year, while others estimate that 1 megavoltage unit is needed for every 300 new treatments. However, these numbers do not necessarily take into account the development of new technologies and treatment modalities, which are more time- and resource-intensive. The International Commission on Radiological Protection has emphasised that ‘purchasing new equipment without a concomitant effort on education and training and on a programme of quality assurance is dangerous’, and ‘the decision to implement a new technology for radiation therapy should be based on a thorough evaluation of the expected benefits, rather than being driven by the technology itself’. It is estimated that the rate of serious mistakes could be as high as 0.2%, which is several orders of magnitude higher than the rate reported for commercial aviation. So, how safe is safe? It can be stated that the development of a culture of safety is critical and requires efforts in education and training, which could prove difficult in overloaded departments.

Genetic predisposition to radiation-related cancer and potential implications for risk assessment

Abstract: Several lines of evidence suggest that risk estimates for cancer associated with radiation exposure incorporate individuals who are more and less inherently susceptible to the carcinogenic effects of radiation, and the technology to further evaluate this issue is now available. For example, genome-wide association scan studies could be undertaken to address, at least in part, the direction of causality in the observations of differential sensitivity to radiomimetic agents in cancer cases compared with normal individuals, thereby building on previous observations that sensitivity to these agents is higher in apparently normal individuals carrying gene mutations in NBS and ATM. Direct studies of risk of second cancers in relation to radiation are underway, and some results have been reported (e.g. for the PRDM1 gene as related to sensitivity to radiation-related cancers after treatment for Hodgkin's lymphoma). It is important to understand the risk synergies between variants affecting associations with various cancers defining susceptibility in unexposed populations and the excess risk in populations therapeutically or occupationally exposed to radiation for the purpose of risk protection, especially as additional baseline risk variants are discovered in increasingly large-scale analyses. While there are studies that are beginning to address these questions, there have been no compelling new discoveries, to date, to indicate that predisposition information should be included in risk assessment. The conclusions in ICRP Publications 79 and 103 appear relevant today.

Clarifying and simplifying the management of environmental exposures under different exposure situations.

Abstract: The International Commission on Radiological Protection recognises three different exposure situations: planned, existing, and emergency. In all three situations, the release of radionuclides into the natural environment leads to exposures of non-human species, as well as having the potential for exposures of the general public. Each release may therefore need separate evaluations of these two consequences in order to clarify the relevant objectives of protection, their compliance with various legal requirements, and how these objectives can be achieved. However, the need to meet more than one objective should not necessarily lead to a more complicated regulatory system. Indeed, with regard to low-level routine discharges from most nuclear plants, there would appear to be scope for simplifying the entire system, to protect both humans and biota, by using discharge consent and specified radionuclide environmental quality standards for water, soil, and air in a manner similar to that used to regulate other major, non-nuclear industries. In contrast, different objectives for humans and the environment need to be set and evaluated independently for existing exposure situations. For emergency situations, the separate consequences of different management options for humans and the environment should be made clear. Should an emergency occur, it is important to have meaningful environmental criteria in order to communicate clearly with the public at large as events unfold.

Advances in NORM management in Norway and the application of ICRP's 2007 recommendations.

Abstract: In Norway, the largest reported quantities of radioactive discharges and radioactive waste containing naturally occurring radioactive material (NORM) come from the oil and gas sector, and smaller quantities of other NORM waste are also produced by industrial or mining processes. The Gulen final repository for radioactive waste from the oil and gas industry from the Norwegian continental shelf was opened in 2008 and has a capacity of 6000 tonnes. As of 1 January 2011, a new regulation was enforced whereby radioactive waste and radioactive pollution was integrated in the Pollution Control Act from 1981. This means that radioactive waste and radioactive pollution are now regulated under the same legal framework as all other pollutants and hazardous wastes. The regulation establishes two sets of criteria defining radioactive waste: a lower value for when waste is considered to be radioactive waste, and a higher value, in most cases, for when this waste must be disposed of in a final waste repository. For example, waste containing ≥ 1 Bq/g of Ra-226 is defined as radioactive waste, while radioactive waste containing ≥ 10 Bq/g of Ra-226 must be disposed of in a final repository. Radioactive waste between 1 and 10B q/g can be handled and disposed of by waste companies who have a licence for handling hazardous waste according to the Pollution Control Act. Alternatively, they will need a separate licence for handling radioactive waste from the Norwegian Radiation Protection Authority. The goal of the new regulation is that all radioactive waste should be handled and stored in a safe manner, and discharges should be controlled through a licensing regime in order to avoid/not pose unnecessary risk to humans or the environment. This paper will elaborate on the new regulation of radioactive waste and the principles of NORM management in Norway in view of the International Commission on Radiological Protection's 2007 Recommendations.

Tools for risk assessment in radiation therapy.

Abstract: Radiotherapy has unquestionable benefits, but it is also associated with unique and specific safety issues. It is the only application of radiation in which humans are intentionally delivered very high doses. Safety in radiotherapy remains heavily dependent on human actions. A step-by-step approach is suggested for the prevention of accidental exposures in radiation therapy: (1) allocation of responsibilities to qualified professionals, and design of a quality and safety programme - no radiotherapy practice should be operated without these key elements; (2) use of the lessons from accidental exposures to test whether the quality and safety programme is sufficiently robust against these types of events -publications by the International Commission on Radiological Protection (ICRP) and the International Atomic Energy Agency provide a collection of lessons to facilitate this step; and (3) find other latent risks by posing the questions 'What else could go wrong?' or 'What other potential hazards might be present?' in a systematic, anticipative manner - methods to do so are described briefly in ICRP Publication 112.

Radiological protection in medicine: work of ICRP Committee 3

Abstract: Committee 3 of the International Commission on Radiological Protection (ICRP) is concerned with protection in medicine, and develops recommendations and guidance on the protection of patients, staff, and the public against radiation exposure in medicine. This paper presents an overview of the work of Committee 3 over recent years, and the work in progress agreed at the last annual meeting in Bethesda, MD in October 2011. The reports published by ICRP dealing with radiological protection in medicine in the last 10 years cover topics on: education and training in radiological protection; preventing accidental exposures in radiation therapy; dose to patients from radiopharmaceuticals; radiation safety aspects of brachytherapy; release of patients after therapy with unsealed radionuclides; managing patient dose in digital radiology and computed tomography; avoidance of radiation injuries from medical interventional procedures; pregnancy and medical radiation; and diagnostic reference levels in medical imaging. Three new reports will be published in the coming months dealing with aspects of radiological protection in fluoroscopically guided procedures outside imaging departments; cardiology; and paediatric radiology. The work in progress agreed by Committee 3 is also described.

Doses from radiation exposure

Abstract: Practical implementation of the International Commission on Radiological Protection's (ICRP) system of protection requires the availability of appropriate methods and data. The work of Committee 2 is concerned with the development of reference data and methods for the assessment of internal and external radiation exposure of workers and members of the public. This involves the development of reference biokinetic and dosimetric models, reference anatomical models of the human body, and reference anatomical and physiological data. Following ICRP's 2007 Recommendations, Committee 2 has focused on the provision of new reference dose coefficients for external and internal exposure. As well as specifying changes to the radiation and tissue weighting factors used in the calculation of protection quantities, the 2007 Recommendations introduced the use of reference anatomical phantoms based on medical imaging data, requiring explicit sex averaging of male and female organ-equivalent doses in the calculation of effective dose. In preparation for the calculation of new dose coefficients, Committee 2 and its task groups have provided updated nuclear decay data (ICRP Publication 107) and adult reference computational phantoms (ICRP Publication 110). New dose coefficients for external exposures of workers are complete (ICRP Publication 116), and work is in progress on a series of reports on internal dose coefficients to workers from inhaled and ingested radionuclides. Reference phantoms for children will also be provided and used in the calculation of dose coefficients for public exposures. Committee 2 also has task groups on exposures to radiation in space and on the use of effective dose.

Radiation and protection of the environment: the work of Committee 5

Abstract: The development of a systematic approach to protection of the environment has required a number of basic steps to be taken, including a discussion of what objectives could reasonably be set, together with an examination of how existing knowledge could best be used in order to achieve them. It has required bold decisions to be made, new modelling to be undertaken, and new data sets to be compiled. Equally challenging, however, has been the need to fold the entire subject area into an expanded system originally developed for the protection of human beings. There are, inevitably, a number of data gaps, and further decisions need to be made. However, the priority now is to examine how this approach to protection of the environment can be used in practice. With an intensifying worldwide debate about the environmental merits of different forms of energy production, it would seem imperative that the various practices involved in the nuclear fuel cycle are able to demonstrate, clearly and independently, their own actual or potential impact on the environment. The International Commission on Radiological Protection now has the basic means for such evaluations to be made, and further developments in this system will reflect the experience of its practical application.

Report of ICRP Task Group 80: ‘Radiological protection in geological disposal of long-lived solid radioactive waste’

Abstract: The report of International Commission on Radiological Protection (ICRP) Task Group 80 entitled ‘Radiological protection in geological disposal of long-lived solid radioactive waste’ updates and consolidates previous ICRP recommendations related to solid waste disposal (ICRP Publications 46, 77, and 81 ). The recommendations given in this report apply specifically to geological disposal of long-lived solid radioactive waste. The report explains how the 2007 system of radiological protection, described in ICRP Publication 103 , can be applied in the context of the geological disposal of long-lived solid radioactive waste. The report is written as a self-standing document. It describes the different stages in the lifetime of a geological disposal facility, and addresses the application of relevant radiological protection principles for each stage depending on the various exposure situations that can be encountered. In particular, the crucial factor that influences application of the protection system over the different phases in the lifetime of a disposal facility is the level of oversight that is present. The level of oversight affects the capability to reduce or avoid exposures. Three main time frames have to be considered for the purpose of radiological protection: time of direct oversight when the disposal facility is being implemented and active oversight is taking place; time of indirect oversight when the disposal facility is sealed and indirect oversight is being exercised to provide additional assurance on behalf of the population; and time of no oversight when oversight is no longer exercised because memory is lost.

Impact of complexity and computer control on errors in radiation therapy

Abstract: A number of recent publications in both the lay and scientific press have described major errors in patient radiation treatments, and this publicity has galvanised much work to address and mitigate potential safety issues throughout the radiation therapy planning and delivery process. The complexity of modern radiotherapy techniques and equipment, including computer-controlled treatment machines and treatment management systems, as well as sophisticated treatment techniques that involve intensity-modulated radiation therapy, image-guided radiation therapy, stereotactic body radiation therapy, volumetric modulated arc therapy, respiratory gating, and others, leads to concern about safety issues related to that complexity. This article illustrates the relationship between complexity and computer control, and various safety problems and errors that have been reported, and describes studies that address the issue of these modern techniques and whether their complexity does, in fact, result in more errors or safety-related problems. Clinical implications of these results are discussed, as are some of the ways in which the field should respond to the ongoing concerns about errors and complexity in radiation therapy.