Radiation Protection Practices Research Articles

Re-examining the health effects of radiation and its protection

The health effects of radiation from atomic explosions in Japan were completely different from those due to radiation from the Co-60 contaminated apartments in Taiwan. The sudden exposure to acute radiation in extremely high doses killed Japanese people, and harmed the survivors in lower doses as shown by increased cancer mortality, especially the leukemia based on the LNT model. The chronic radiation received by the residents unknowingly in the Co-60 contaminated apartments in Taiwan, even in higher doses, caused no excess cancer deaths; on the contrary their spontaneous cancer deaths were sharply reduced to only about 2.5% of that of the general population, and hereditary defects in their offspring were only 5%–7% of those of the normal population. Therefore, the residents in the Co-60 contamination apartments had coincidently accomplished a human experiment of the health effects to human beings. The chronic radiation received from the Co-60 contaminated houses is quite similar to the radiation exposure to the workers and public in the peaceful use of nuclear energy and medical radiation. Acute radiation from a nuclear accident could harm a limited number of people, but the chronic radiation might benefit people, such as in the case of the Chernobyl accident. People should not be fearful of chronic exposure to low radiation and the traditional radiation protection policy and practices used in past 60 years should be revised based on the health effects observed in Taiwan.

Radiation protection practices and related continuing professional education in dental radiography: A survey of practitioners in the North-east of England

Purpose To establish the level of implementation of recommendations from the National Radiological Protection Board, relating to best radiation protection practice in dental radiography within general dental practices in the North-east of England. To survey the opinion of practitioners on the availability of related post-graduate courses in the region. Methods A postal survey in the form of a self-reported questionnaire was mailed to all practices in the North-east of England in November 2000. The questionnaire, consisting of closed and open-ended questions, was to be completed where possible by the resident radiation protection supervisor. Results Two hundred and sixteen practices responded to the questionnaire, a response rate of 53%. The survey revealed variation in the standards of application of best radiation protection practice. Some 23% of practitioners had not attended any post-graduate courses on radiation protection since qualifying. Post-graduate education provision on radiation protection in the region was considered insufficient by 51% of respondents. Conclusions It is concluded that a significant proportion of practices were not making full use of opportunities to reduce dose to their patients. In addition, a small number of practices had untrained staff acting as the Radiation Protection Supervisor. A significant proportion of practitioners had not been updated in radiation protection practices within a 5-year period, and this may account for the failure to implement best radiographic practice. Over half felt that there was insufficient availability of post-graduate courses in radiation protection. The regional provision of continuing professional education in this field may need development.

Increased cancer risk among surgeons in an orthopaedic hospital

Five cancer cases over 7 years were reported in a small orthopaedic hospital where radiation protection practice was poor. To investigate whether workers subject to routine radiation dosimetric assessment in that hospital had an increased cancer risk. One hundred and fifty-eight workers subject to routine dose assessment and 158 age-sex-matched unexposed workers were questioned about cancer occurrence. All tumours were analysed as a single diagnostic category. Cumulative 1976-2000 cancer incidence was 29 (9/31), 6 (8/125) and 4% (7/158) in orthopaedics, exposed other than orthopaedics, and unexposed workers, respectively. At logistic regression analysis, working as orthopaedic surgeon significantly (P<0.002) increased the risk of tumours. These findings caution against surgeons' underestimation of the potential radiation risk and insufficient promotion of safe work practices by their health care institutions.

MO‐B‐I‐611‐01: The Role of the Medical Physicist in Preparing for Radiation Disasters

Since 9/11, hospitals have seen the need to examine their emergency management plans to ensure that radiation disasters are adequately addressed. Hospitals need to be ready to deal with radiation casualties in addition to the possibility of many self‐presenters who want to know whether they are contaminated. Hospitals need to be prepared to handle this situation in the first day or two after a disaster until state and federal agencies can mobilize. Medical physicists will play a vital role as responders and sources of accurate information for hospital staff, patients and the public. Medical physicists will be asked to assist in the decision‐making process if an event does occur. This course provides information on the handling of patients who are injured and may be irradiated and/or contaminated with radioactive material. The Center for Disease Control website has guidance on ways to handle self‐presenters who may exceed the number of radiation casualties. The psychosocial considerations after a disaster will be discussed and its effects on staff, patients and the public. The course will also address issues to be anticipated for facility recovery after a disaster.Educational Objectives:1. To provide resources that are available for developing emergency plans that address radiation disasters and their unique policy considerations.2. To show how to utilize radiation protection procedures and practices and know how to prepare the facility for radiological emergency medical response.3. To provide a framework for handling self‐presenters who will seek help from their local hospital to determine whether they are contaminated.4. To understand the psychosocial considerations in responding to a radiological emergency.5. To know what activities can occur during facility's recovery from a radiation disaster.

The requirement for energy imparted in radiation protection practice

The lifetime probability of an 'excess' cancer for an individual is assumed by the ICRP to be a linear function of dose, without threshold. This linear-no-threshold (LNT) model is not based on firm data, but on conservative estimates which provide simplifying guidelines for individual values for lifetime risk. Yet, such values are currently used as the basis for radiation protection. However, the present authors do not accept the ICRP assumptions with regard to the LNT model, and instead use the A-Bomb human carcinogenesis data as a basis for recommending an alternative method for determining exposure limits for radiation workers. A change in the radiation protection system is recommended in which absorbed dose is replaced with energy imparted. Alternative reporting requirements for radiation protection are also suggested.

Active personal dosemeters for individual monitoring and other new developments

In this paper, we will present a first (but not complete) status description of active personal dosemeters (APDs) and their implementation in European countries. In modern radiation protection practices, APDs are becoming absolutely necessary operational tools for satisfying the ALARA principle. Despite their success, they are relatively new for individual monitoring of workers. Regulation, legal requirements and calibration procedures are different in European member states. A catalogue of commercially available and prototype devices is presented. Improvement on devices and in implementation of calibration method are expected in the forthcoming years. End-user feedback experience and requirements are reported.

The Bell Tolls for LNT

The linear no-threshold (LNT) model has been a convenient tool in the practice of radiation protection, but it is not supported by scientific data at doses less than about 100 millisievert or at chronic dose rates up to at least 200 millisievert per year. Radiation protection practices based on the LNT model yield no demonstrable benefits to health when applied at lower annual doses. The assumption that such exposures are harmful may not even be conservative and has helped to foster an unwarranted fear of low-level radiation. For its new recommendations, to be issued probably in 2005, the International Commission on Radiological Protection (ICRP) has said that it expects to continue the application of the LNT model "above a few millisievert per year." National societies for radiation protection may wish to consider the need to lobby the ICRP, through the auspices of International Radiation Protection Association, to further relax adherence to the LNT assumption--up to "a few tens of millisievert per year."

The bell should toll for the linear no-threshold model**This is an amended version of a paper which was accepted for presentation at the IRPA-11International Congress in Madrid, Spain, 23–28 May 2004. It was not presented because theauthor was unable to attend the Congress.

The linear no-threshold (LNT) model has been a convenient tool in thepractice of radiation protection but it is not supported by scientific dataat doses less than about 100 mSv or at chronic dose rates up to at least200 mSv yr−1. Radiation protection practices based on the LNT model yield no demonstrable benefits tohealth when applied at lower annual doses. The assumption that such exposures areharmful may not even be conservative and has helped to foster an unwarranted fear oflow-level radiation.For its new recommendations, to be issued probably in 2005, the ICRP has said that itexpects to continue the application of the LNT model ‘above a few millisieverts per year’.National societies for radiation protection may wish to consider the need to lobbythe ICRP, through the auspices of IRPA, to further relax adherence to the LNTassumption—up to ‘a few tens of millisieverts per year’.

Adaptation of the present concept of dosimetric radiation protection quantities for external radiation to radiation protection practice.

The present concept of dosimetric radiation protection quantities for external radiation is reviewed. For everyday application of the concept some adaptations are recommended. The check of the compliance with dose limits should be performed either by the comparison with values of the respective operational quantities directly or by the calculation of the protection quantity by means of the operational quantity, the appertaining conversion coefficient and additional information of the radiation field. Only four operational quantities are regarded to be sufficient for most applications in radiation protection practice. The term equivalent should be used in the connection dose equivalent only. Proposals are made for names of frequently used operational quantities which are denoted up to now by symbols only.

The Bystander Effect: Recent Developments and Implications for Understanding the Dose Response

The bystander effect refers to the biological response of a cell resulting from an event in an adjacent or nearby cell. Such effects depend on intercellular communication and amplify the consequences of the original event. These responses are of particular interest in the assessment of ionizing radiation risk because at public or occupational exposure levels not every cell receives a radiation track. Current radiation protection regulations and practices are based on the assumption of a linear increase in risk with dose, including low doses where not all cells are hit. Mechanisms that amplify biological effects are inconsistent with these assumptions. Evidence suggests that there are two different bystander effects in mammalian cells. In one type, a radiation track in one cell leads to damaging, mutagenic, and sometimes lethal events in adjacent, unhit cells. In the other type, a radiation track in one cell leads to an adaptive response in bystander cells, increasing resistance to spontaneous or radiation-induced events. This paper describes some of the data for radiation-induced bystander effects in vitro and correlates that data with in vitro and in vivo observations of risk at low doses. The data suggest that protective effects, including beneficial bystander effects, outweigh detrimental effects at doses below about 100 mGy, but that the reverse is true above this threshold.

Trends in radiation protection: possible effects on fusion power plant design

Since the design of fusion power plants involves long-term issues, ranging over several decades, it is useful to try to foresee under what kind of regulations the first fusion plants are to be operated. Application of present radiological regulations and practice to a fusion power plant concept is considered. The current design phase of fusion power plants motivates the top-down dose assessment, but it is crucial to aim at bottom-up assessments to ensure radiation doses as low as reasonably achievable. Since several issues, relating both to our knowledge on radiation as well as to the practice of radiation protection, may change in the future, it is necessary to continuously follow the development in the further design of fusion power plants.

Mortality patterns in British and US radiologists: what can we really conclude?

Mortality patterns in British and US radiologists: what can we really conclude?

Solid cancer risk coefficient for fast neutrons in terms of effective dose.

Cancer mortality risk coefficients for neutrons have recently been assessed by a procedure that postulates for the neutrons a linear dose dependence, invokes the excess risk of the A-bomb survivors at a gamma-ray dose D(1) of 1 Gy, and assumes a neutron RBE as a function of D(1) between 20 and 50. The excess relative risk (ERR) of 0.008/mGy has been obtained for R(1) = 20 and 0.016/mGy for R(1) = 50. To compare these results to the current ICRP nominal risk coefficient for solid cancer mortality (0.045/Sv for a population of all ages; 0.036/Sv for a working population), the ERR is translated into lifetime attributable risk and is then related to effective dose. The conversion is not trivial, because the neutron effective dose has been defined by ICRP not as a weighted genuine neutron dose (neutron kerma), but as a weighted dose that includes the dose from gamma rays that are induced by neutrons in the body. If this is accounted for, the solid cancer mortality risk for a working population is found to agree with the ICRP nominal risk coefficient for neutrons in their most effective energy range, 0.2 MeV to 0.5 MeV. In radiation protection practice, there is an added level of safety, because the effective dose, E, is-for monitoring purposes-assessed in terms of the operational quantity H*, which overestimates E substantially for neutrons between 0.01 MeV and 2 MeV.

Survey of radiography and radiation protection in general dental practice in Uganda

Survey of radiography and radiation protection in general dental practice in Uganda

Patient and staff exposure during endoscopic retrograde cholangiopancreatography.

Despite a number of efforts being put into the radiological protection of both patient and staff during interventional radiological (IR) procedures during recent years, information about radiation exposure during endoscopic retrograde cholangiopancreatography (ERCP) procedures remains scarce. The purpose of this study was to estimate both patient and staff radiation doses during therapeutic ERCP procedures by direct measurement and to compare these results with data from other IR procedures. For 54 patients, effective dose and skin dose were estimated by measuring the dose-area product. For staff, entrance surface doses to the lens of the eye, thyroid and hands were estimated by thermoluminescent dosemeters. A median effective dose of 7.3 mSv and a median entrance surface dose of 271 mGy per procedure were estimated for patients. The gastroenterologist received a median dose of 0.34 mGy to the lens of the eye, 0.30 mGy to the skin at the level of the thyroid and 0.44 mGy to the skin of the hands, per procedure. When comparing the dosimetric quantities presented in this study with data from other IR procedures, it is clear that patient skin doses and doses to staff are high owing to the use of inappropriate X-ray equipment. ERCP requires the same radiation protection practice as all IR procedures. It should be consistently included in future multicentre IR patient and staff dose survey studies at national or international level.

Survey of radiography and radiation protection in general dental practice in Uganda.

To carry out the first survey in Uganda of all dentists and all public health dental officers (PHDO) to assess the status of dental radiography and radiation protection. All 74 dentists and 76 PHDOs in Uganda were sent a postal questionnaire including 33 questions relating to various demographic details, radiographic equipment and radiographic techniques, including processing and radiation protection. A second questionnaire was sent to non-respondents after 3 months. Eighty-two per cent of dentists responded and 83% of PHDOs. Seventy per cent of the dentists and 100% of the PHDOs were trained in Uganda. Seventy-five per cent of the dentists and 30% of the PHDOs had access to one of the approximately 30 X-ray machines in the country. The majority of the equipment did not comply with current recommendations in Europe. Fifty-one per cent of dentists used machines with mechanical timers, 28% used machines with no visual warning signal and 17% used equipment with no audible warning signal. Most of the equipment was over 30 years old and only 15% of dentists knew when the equipment was last serviced. The most relevant finding of the surveys was the level of 'don't know' responses to many questions from both groups. The lack of knowledge regarding dental radiography and radiation protection plus the condition of most equipment in Uganda is a matter of concern. Standards of care are considerably lower than in developed countries requiring improved undergraduate training, provision of postgraduate courses and Ugandan governmental or international financial assistance.

Topics Under Debate - Is the Linear-No-Threshold Hypothesis Appropriate for Use in Radiation Protection?

There are few things more important to the practice of radiation protection than the basic assumptions regarding the actions of ionising radiation at low levels. In addition, there are few things that have caused more consternation among investigators due to the fact that data relating to the biological effects of low levels of ionising radiation have such large uncertainties. Given that the data have large uncertainties, it is useful to consider whether the simple hypothesis of a linear-no-threshold relationship is appropriate for use in radiation protection. The two participants in this debate have extensive experience in research on the biological actions of ionising radiation, and the implications of those actions for radiation protection.

Alternative goals and policy mechanisms for radiation protection.

For decades, radiation protection philosophy and practice have been the domain of professionals trained in the physical and medical sciences. Radiation protection policy was formulated and implemented largely without consultation with or participation by other professional disciplines or the general public. Although, from a public health standpoint, past radiation protection efforts have worked well, there are growing signs that the public has lost confidence in the radiation risk management system as currently configured. This paper draws on perspectives of political science, social psychology, economics, and decision analysis to analyze the limitations of the current radiation protection regime and to suggest alternatives for enhancing public trust and improving efficacy.

Die Berechnung von Konversionsfaktoren für den Strahlenschutz bei äußerer Strahlenexposition

Calculations are essential for radiation protection practice because organ doses and effective doses cannot be measured directly. Conversion coefficients describe the numerical relationships of protection quantities and operational quantities. The latter can be measured in practical situations using suitable dosimeters. The conversion coefficients are calculated using radiation transport codes - usually based on Monte Carlo methods - that simulate the interactions of radiation with matter in computational models of the human body. A new generation of human body models, the so-called voxel models, are constructed from image data of real persons using suitable image processing systems, consequently, they represent the human anatomy more realistically than the so-called mathematical models. The numerical effects of realistic body anatomy on the calculated conversion coefficients can amount to 70 % and more for external exposures.

Quality Criteria Development within the Fourth Framework Research Programme

The revised EC patient Directive 97/43/EURATOM introduces a number of new and extremely relevant requirements into the legal framework of radiation protection of persons who undergo medical exposure throughout Europe. Key elements of the most relevant changes involve a more objective assessment of radiological performance. In particular, the establishment of optimisation strategies involving clinical and patient dose audits, as well as quality assurance, will be required. There is no doubt that within this changing framework for radiation protection of the patient, advice and guidance regarding best practice at a European level will play a vital role in the achievement of consistent and harmonised practice. In order to establish a starting point for both the structure and content of advice and guidance on best practice for radiation protection of the patient, the Commission of European Communities has established European Guidelines on Quality Criteria for diagnostic radiographic images for adult and paediatric patients as well as computed tomography. These documents have already been made available throughout Europe in English and translation into a number of European Languages is under way for re-circulation within specific Member States. Whilst this process was continuing a Fourth Framework Research Programme has been under way in the period 1996-2000 to develop and evaluate further the robustness of the Quality Criteria for diagnostic radiographic images for adult patients. An overview is presented of the most relevant findings of the Fourth Framework Research Project with a strong emphasis on operational outcomes relevant to focused multipartner, multinational research programmes of a multidisciplinary nature. Detailed findings of the project will be presented elsewhere in the meeting and through future publications.