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Radiation protection advisers are accustomed to carrying out internal audit in organizations for which they provide services but, traditionally, external audit has not been a part of the radiation protection adviser function. To provide an external audit function, two teams of radiation protection advisers undertook external radiation protection audits of their respective organizations, including the radiation protection adviser function itself. These audits were more representative of audits or inspections carried out by government agencies, for example the Health and Safety Executive and the former Inspectorate of Pollution, now the Environment Agency. Subsequently, reports, including recommendations for remedial action, were prepared for each management by the external auditors. The process of setting up and carrying out the external audits is described. Guidelines are suggested for those seeking to carry out an external audit.
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The science of radiation protection is a fundamental outgrowth of peaceful and military applications of ionizing radiation and the use of nuclear energy. Scientific progress in radiation protection has not, however, been as dramatic as progress in other scientific endeavors, because many users of ionizing radiation have perceived that the major technical and institutional problems have already been solved. This misperception is not based on solid fact and is not shared by radiation protection professionals, who have a broader vision of both past achievements and problems remaining in this area. Experience gained as a consequence of the Chernobyl accident has highlighted new problems and demonstrated the urgency of finding better answers to some old questions. This paper addresses the future impact of the recent Chernobyl accident on the science of radiation protection. In summary, the accident demonstrated that particular emphasis should be directed toward: Improvement of dosimetric and health-effects models for predicting the consequences of exposure of the public to low doses of ionizing radiation. Development of optimized, realistic countermeasures and improvement in emergency preparedness. Education of the public, including students, scientists and politicians with regard to radiation protection issues. Development of advanced computer programs and radiation instruments for evaluating reactor accidents and their consequences. Transfer of learned concepts, methods and approaches to other scientific fields, such as environmental sciences, toxicology, pharmacology, etc.
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The current radiation protection framework provides an adequate basis for protecting workers, the public and the environment. Nevertheless, international and national radiation protection organizations are presently engaged in updating, clarifying and enhancing radiation protection principles-and rightly so, given our culture of pursuing excellence in radiation safety through a process of continuous improvement. Accordingly, the nuclear energy industry appreciates the opportunity to provide its perspective on this effort. The nuclear energy industry's perspective is shaped in several ways-as an operator, we carry out a primary responsibility for protecting human health and safety and the environment; as a licensee, we are responsible for complying with government regulations; and as an energy producer, we are responsible for the safe, reliable, and economic generation of electricity for consumers. Our objective in regard to improving radiation protection principles is to help promote an outcome that has a clearly articulated basis in science, is flexible in regard to how it might be applied to a very wide range of current and future regulated activities, and is practical and cost-effective in terms of how it can be implemented and maintained.
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Radiosensitization of V79 Chinese hamster fibroblasts by 0.5 mM misonidazole is a smooth function of endogenous glutathione (GSH) levels as modulated upwards by pre-incubation in medium containing cysteamine, or downwards by pre-incubation in medium containing buthionine sulfoximine. The enhancement ratio (radiation sensitivity in nitrogen/radiation sensitivity in nitrogen +/- sensitizer or thiol) varies from 1.3 at 12 mM to 2.25 at less than 0.1 mM endogenous GSH. The enhanced radiosensitivity of thiol-depleted hypoxic cells is reversed when exogenous thiols are added, and for equivalent ER, the exogenous thiol concentrations are much lower than the endogenous GSH concentrations. Measurement of intracellular drug concentrations amplified rather than diminished the above discrepancy, since intracellular concentrations of cysteamine were lower and glutathione much lower than the extracellular concentrations. Three possible explanations are addressed: an external membrane component of damage is involved, long-range protection to DNA target radicals is possible from outside the cell (e.g., donation of electrons), and (c) endogenous glutathione is not in a free or exchangeable state (e.g., bound).
PURPOSE: Currently, lead-free x-ray-protective clothing is classified by the European production standard EN 61 331-3. To evaluate protective effects of lead-free materials according to this standard, the certifying offices as well as customers solely refer to the lead equivalent (LE). The LE of lead-free protective clothing, however, depends on the tube voltage (energy spectrum). Therefore, stating a single value for x-ray-protective clothing does not reveal the protective efficacy for the complete range of energy as applied in clinical practice. Moreover, the method of narrow beam geometry does not account for information on secondary radiation (scattered and fluorescent radiation) generated within the material. Lead-free materials, however, generate large-scale fluorescent radiation, especially for elements with atomic numbers below 60. As a consequence, full-scale secondary radiation of a given material can only be detected with a broad beam setup. MATERIALS AND METHODS: In accordance with IEC 61 331-1, we compared commercially available radiation-protective aprons manufactured with lead-free or partially lead-free materials with aprons manufactured on a lead-oxide basis. In addition to the LE, attenuation ratios and dose-build-up-factors under broad beam-conditions were evaluated. RESULTS: In comparison with lead-oxide materials, protection efficacy of lead-free materials is reduced by up to 70 %, particularly for a tube voltage below 80 kV. Lead-composite materials (partially lead-free materials) are less affected. CONCLUSION: Users and patients wearing lead-free x-ray-protective clothing might unknowingly be exposed to a much larger dose than generally assumed. In the future, radiation protection rating should exclusively refer to the "attenuation ratio", which is based on broad beam geometry and characterizes radiation attenuation much more precisely than the lead equivalent.
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From February 2002 to November 2003 the National Centre of Radiobiology and Radiation Protection conducted a PHARE twinning project 'Radiation Protection and Safety at Medical Use of Ionising Radiation'. The main purposes of the project were the harmonization of Bulgarian legislation in the field of radiation protection with EC Directives 96/29 and 97/43 Euratom, and the establishment of appropriate institutional infrastructure and administrative framework for their implementation. This paper presents the main results of the project: elaboration of Ordinance for Protection of Individuals from Medical Exposure; performance of a national survey of distribution of patient doses in diagnostic radiology and of administered activities in nuclear medicine and establishment of national reference levels for the most common diagnostic procedures.
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Radiation protection standards for the individual exposed to ionizing radiation in his/her daily work have evolved over more than 50 years since the first recommendations on limits by the NCRP and the ICRP. Initial standards were based on the absence of observable harm, notably skin erythema, but have since been modified as other concerns, such as leukemia and genetic effects, became more important. More recently, the general carcinogenic effect of radiation has become the principal concern at low doses. Genetic effects are also of concern in the younger individual. Modern radiation protection practices take both of these risks into account. Quantification of these risks improves as new information emerges. The study of the Japanese survivors of the atomic bombs continues to yield new information and the recent revisions in the dosimetry are about to be completed. The special circumstances of space travel suggest approaches to limits not unlike those for radiation workers on the ground. One approach is to derive a career limit based on the risks of accident faced by many nonradiation workers in a lifetime. The career limit can be apportioned according to the type of mission. The NCRP is considering this and other approaches to the specification of radiation standards in space.
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