ICRP Recommendations Research Articles

Quality Control Status of Radiology Centers of Hospitals Associated with Mashhad University of Medical Sciences

Introduction Using ionization radiation for diagnostic and treatment fields has increased worldwide dramatically. This issue causes an increase in the absorbed and collective doses in society noticeably. With regard to two main principles in radiation protection, i.e., justification and optimization, it is necessary to have imaging process with minimum dose to patients and personnel. For achieving this, it is vital to perform quality control tests regularly. On this topic, many studies have been performed and reported worldwide which show necessities and meaningfulness of QC tests. Materials and Methods In this study, Unfors Mult-O-Meter model 303 is used for surveying accuracy of kVp and time, linearity of exposure with mAs, and reproducibility of exposure. Results According to recommendations of AAPM (2002) and ICRP 103, in this study, 27% of apparatuses in accuracy of kVp, 45% in accuracy of timer, and 30% in accuracy of reproducibility were out of accepted range. Conclusion In surveyed apparatuses, both ends of operating range have large errors in therefore it is recommended that these devices should not be used in the mentioned regions. Performing strict quality control on all radioactive devices is one of the radiation protection priorities that should be done periodically .With regard to the results, repair, substitution or omition of some devices are suggested.

Status of standard data on shielding calculation in standard committee of the Atomic Energy Society of Japan

In radiation shielding calculations, fluence-to-dose conversion coefficients are necessary to estimate dose rate. This standard gives effective dose conversion coefficients based largely on the ICRP recommendations in 1990. However, original values based on research conducted in Japan have been retained primarily with respect to the extension of energy range and multigroup-wise data. The gamma-ray buildup factor is defined by the ratio of gamma-ray dose included scattered gamma-ray contribution to dose of unscattered gamma-ray which has no experience of collision from source point to evaluation point. 20 years have passed since publication of standard data by the standard committee of America Nuclear Society at 1991, the extension of data is needed for the evaluation of effective dose and ambient dose equivalent in the shielding calculations, and the codes were also advanced for the evaluation of buildup factors. In the new report, buildup factors obtained by the Invariant Embedding (IE) method and its Geometrical-Progression (GP) fitting formula parameters appeared for 28 materials.

希土類資源開発と自然放射線源の放射線防護

There is growing demand for rare earth elements as raw materials for industrial goods such as high performance magnet. Thus, rare earth resources attract a lot of strategic attention internationally. The rare earth ore often contains uranium and thorium, that are Naturally Occurring Radioactive Material (NORM). Usually, such radioactive substances almost remain in the waste yielded in the extraction process for rare earth elements. Therefore, radiation protection is required in all of operation phases from mining and refining to waste disposal, and it is appropriate to the purpose to use the reference level of intervention in the ICRP recommendation. To ensure resource development, it is important that sites where wastes were disposed of are reused under monitored natural attenuation of the chemical conditions of the wastes after early physical stabilization of the land. This paper illustrates current status of rare earth development along with related radiation protection issue.

Public Health England survey of eye lens doses in the UK medical sector

The ICRP has recently recommended that the occupational exposure limit for the lens of the eye be reduced to 20 mSv in a year, averaged over defined periods of 5 years, with no single year exceeding 50 mSv. There has been concern amongst some groups of individuals, particularly interventional cardiologists and radiologists as well as relevant professional bodies, that implementation of these recommendations into UK law will adversely affect working patterns. However, despite a number of informative European studies, there is currently little UK dosimetry data available upon which judgements can effectively be based. In order to address this knowledge gap, Public Health England has carried out a small, targeted survey of UK lens doses to medical staff undertaking procedures likely to involve the highest levels of radiation exposure. Two out of a total of 61 individuals surveyed had projected annual doses which could be close to 20 mSv, measured outside lead glasses. Use of protective equipment was generally good; however, lead glasses were only used by 9 participants. The results of this survey suggest that compliance with the ICRP recommendations is likely to be possible for most individuals in the UK medical sector.

Report of Task Group on the implications of the implementation of the ICRP recommendations for a revised dose limit to the lens of the eye

Summary This report was commissioned by the IRPA President to provide an assessment of the impact on members of IRPA Associate Societies of the introduction of ICRP recommendations for a reduced dose limit for the lens of the eye. The report summarises current practice and considers possible changes that may be required. Recommendations for further collaboration, clarification and changes to working practices are suggested. Approved by the IRPA Executive Council in July 2013

The β-ray energy and angular response of the EYE-D™ eye-lens dosemeter

Following the recent ICRP recommendation to decrease the limit of occupational exposure to the eye lens from 150 mSv to 20 mSv/year, a dedicated individual eye-lens dosemeter, EYE-D™, was developed at the IFJ PAN. This dosemeter uses MCP-N (LiF:Mg,Cu,P) thermoluminescent detectors covered with a polyamide capsule and was so far optimized to achieve a flat photon energy and angular response for X-ray exposures typical in interventional radiology. To verify the applicability of this eye-lens dosemeter in external β-ray fields which arise, e.g. in nuclear medicine procedures, we measured and calculated its β-ray energy and angular response. Measurements, applying β-rays from Sr-90/Y-90 isotope, were performed at the Beta Secondary Standard type 2 (BSS 2) in CLOR. Calculations, using the PENELOPE Monte Carlo transport code which simulates coupled electron and photon transport in arbitrary materials, were performed for P-32, K-42 and Sr-90/Y-90 fields to simulate doses received by the eye lens within the human body. PENELOPE Monte Carlo transport code was also used to calculate doses received with EYE-D™ detectors. We found good agreement between the measured and calculated energy and angular responses which confirms the suitability of this dosemeter in assessing Hp(3) to estimate the eye lens. Obtained results and conclusions, however preliminary, conform with current ICRP recommendations when performing individual radiation protection dosimetry in external β-ray fields occurring in nuclear industry and nuclear medicine activities.

A proposed countermeasure simulation model for the new ICRP recommendations

In April 2011 the European Platform on Preparedness for Nuclear and Radiological Emergency Response and Recovery (NERIS-TP) decided to expand the two European Decision Support Systems JRodos and ARGOS with respect to the new ICRP-103 recommendations. The extension should be applicable for nuclear accidents and radiological emergencies and comprise a new screening model, the possibility to optimise dose reducing actions with the models ERMIN (European Model for Inhabited Areas) and AGRICP (Agricultural Countermeasure Program), respectively, and scenario preparation tools to support the user in defining countermeasure strategies. This paper describes the screening model that was developed by the authors and is foreseen for realisation and inclusion in JRodos and ARGOS in 2012/2013.

Methodological aspects of the implementation of the new ICRP recommendations

With the ICRP recommendations Publications 103, 109 and 111 (ICRP, 2007; ICRP 2009a, 2009b), new concepts and quantities have been introduced into emergency management and rehabilitation. Two of them will possibly influence national procedures, but for sure they will influence countermeasure simulation approaches: 1. The concept of a “reference level” for emergency and existing controllable exposure situations that represents the level of dose or risk, above which it is judged to be inappropriate to plan to allow exposures to occur, and for which therefore protective actions should be planned in advance. 2. When deciding on the optimum course of protective actions, all exposure pathways and all relevant actions have to be taken into account. The major changes for the simulation models result from the second recommendation that all exposure pathways must be considered when deciding on protective actions. So far all countermeasure simulations in the early phase of an emergency are carried out by considering individual countermeasures such as sheltering or evacuation, if some dose limit for the respective action is exceeded. This approach has to be changed and strategies of several countermeasures analysed and simulated with the ultimate goal not to exceed the reference level over a given time period, typically one year.

A dosimetry evaluation of 90y-stent implantation in intracoronary radiation treatment

Ionizing particles have been used for the treatment of atherosclerosis. Internal irradiation is commonly carried out by means of several methods (catheter-based systems, radioactive stents or balloons) to reduce the probability of restenosis. 90Y, due to some of its characteristics, is an appropriate radioisotope for intravascular brachytherapy. However, since there are some critical tissues in the vicinity of the heart like the breast and lymph nodes, it is necessary to perform a dosimetry calculation around the artery under radiotherapy to justify the treatment method. In this study, a 3-D dose distribution was obtained for the coronary vessel and its surrounding tissues for a standard 90Y stent in a MCNPX program. The results were compared with other investigations on restenosis prevention using 90Y-coated stents. The calculations represented a 28-day cumulative dose between 1230 cGy and 2400 cGy at 0.1 mm from the stent surface, while this quantity was about 23.8 cGy at 8.5 mm from the stent surface. An assessment of the dose equivalent and effective dose was also performed at r = 8.5 mm for the mentioned surrounding tissues which may be located in the area, based on the latest changes in ICRP recommendations. Additionally, the dose equivalent calculated within the treatment period for these organs was compared with published dosimetry data for 90Sr/90Y seed sources in order to evaluate radiation protection concerns about these two radiotherapy methods. It has been found that, depending on stent parameters, 90Y stent implantation might increase the unfavorable side effects for the patient, but to a much lesser degree than the other methods.

Recent Recommendations on Emergency Exposure Situations and a Discussion on Setting Reference Levels with the NEA Perspective

Expert Group on Implementation of New International Recommendations for Emergency Exposure Situations (EGIRES) of the Working Party on Nuclear Emergency Matter (WPNEM) has been mandated by the Committee of Radiation Protection and Public Health (CRPPH) of the OECD Nuclear Energy Agency to investigate issues in, and approaches to, the implementation of the new ICRP recommendations and revised Basic Safety Standards of the IAEA for emergency exposure situations, specifically nuclear/radiological emergencies including accidents and consequence management for malicious acts. This also includes the application of optimisation of protection strategies, setting of reference levels and the inclusion of stakeholder input in this process. The expected output of the expert group is to prepare a report on issues covering mentioned topics. Emergency exposure situations, as defined by the ICRP, are unexpected situations that may require urgent protective actions, and perhaps longer-term protective actions to be implemented. The Commission continues to recommend optimisation and the use of reference levels to ensure an adequate degree of protection with respect to exposure to ionising radiation in emergency exposure situations. Setting reference levels is a responsibility of national authorities and reference levels represent the level of dose or risk, above which it is judged to be inappropriate to plan to allow exposures to occur and for which therefore protective actions should be planned and optimized. EGIRES decided to analyze the established processes for optimization of the protection strategy for emergency exposure situations and practical implementation of reference levels concept in several member states of the NEA by performing a survey. It is planned to collect information on the definition of optimization strategy in different countries, optimization of protection for different protective actions and also optimization of urgent protective actions. In addition, national criteria in setting reference levels, its use, relevant processes including specific triggers and dosimetric quantities in setting reference levels are focus points that will be evaluated. Benefits expected from the work of the expert group will be useful to find a path and even common understanding of surrounding issues in emergency exposure situations with the inclusion of national perspectives and also to discuss stakeholder involvement.

Preparedness for nuclear and radiological emergency response and recovery: Outcomes of the First NERIS Platform Workshop on practical implementation of the new ICRP recommendations

Preparedness for nuclear and radiological emergency response and recovery: Outcomes of the First NERIS Platform Workshop on practical implementation of the new ICRP recommendations

The Finnish processing pipeline during nuclear or radiological emergency preparedness and response

During nuclear or radiological emergency preparedness and response a processing pipeline is put in place at the Finnish Radiation and Nuclear Safety Authority to produce assessment reports of the current situation, its likely evolution with time, and recommendations on protective actions. Within the processing pipeline raw data is more and more refined towards these end products as experts, advisors, and decision makers collect, analyze, portray, annotate, filter, arrange and rearrange, share, approve or dismiss, and publish content. Emergency procedures and guidelines assist and guide them through the process, as do information and communication technologies. The inner working of the processing pipeline is in constant flux as information and communication technologies develop and allow better facilitation of the process, and as social and political demands change. The present article describes the overall working of the pipeline, and how it has recently been improved by the KETALE collaborative software. The focus then shifts to the new ICRP recommendations and how the new national emergency guidelines are planned to be implemented within the KETALE software. The KETALE software has greatly increased the throughput of our emergency processing pipeline and improved product quality.

Case study on the improved use of collective dose for nuclear and/or radiological emergencies

The improved use of collective dose following the 2007 ICRP recommendations is studied for nuclear and radiological emergency situations. To study the accumulation of low individual doses to the collective dose the collective dose is calculated as a function of the minimum individual dose for three cases including nuclear as well as radiological accidents. It is found that the use of collective dose in this way can have an added value in nuclear emergency preparedness and response in particular related to decisions on overall protective actions following an accident.

Activities in Germany related to ICRP 103

In Germany, the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) has asked the German Commission on Radiological Protection (SSK) to provide advice on the revision of the German “Radiological Fundamentals for Decisions on Measures for the Protection of the Population against Accidental Releases of Radionuclides” (Radiologische Grundlagen). A working group has been established to guide the preparation of a new version of that document. It was asked that the revision has to consider most relevant publications of international bodies such as ICRP, EC and IAEA. Therefore, the ICRP recommendations 103, 109 and 111 have to be considered together with the draft documents of the European Union and the IAEA Basic Safety Standards. Recommendations of working groups of NEA (WPNEM) as well as the EPAL working group of HERCA (Heads of European Radiological Protection Competent Authorities) will be also taken into account. Within the discussion it turned out that the practical application of the new recommendation for professionals working in the operational community is extremely important. As the current recommendations are widely accepted and operational all over Germany, it was investigated to which extent the current procedures can be taken over with minor modifications.

Updates to UK emergency and recovery advice following changes in international guidance

HPA is updating and consolidating its advice on radiation emergencies and recovery. Current advice was published in 1997. Since 2007, the ICRP has issued a set of recommendations to elaborate its guidance for emergency exposure and existing exposure situations. It is expected that the European Basic Safety Standards, when published, will also reflect the ICRP recommendations. The new ICRP guidance represents a marked change in approach, with emphasis placed on optimisation of whole protection strategies using reference levels of residual dose. These new concepts as well as the relevant lessons identified following the Fukushima accident will be included in the new UK advice document. The scope of the UK advice includes reactor and transport accidents as well as releases from waste stores, reprocessing and defence activities. The revised advice will consider the initiation of emergency countermeasures based on averted dose criteria and optimisation of the subsequent protection strategy based on reference levels of residual dose. The advice will illustrate that the type of protection strategy selected depends on the contribution of different exposure pathways over time to projected dose, and this will vary according to the scenarios considered as reasonably foreseeable. Due to the potential impact of the advice, a wide range of stakeholders are being consulted. In particular, feedback will be required on the potential for adapting current practices for sheltering and stable iodine prophylaxis to situations involving longer duration releases or those with a prolonged threat phase. The advice document will contain guidance for emergency planning and response, criteria for the withdrawal of emergency countermeasures, factors to consider during the transition to an existing exposure situation and the management of long term contaminated areas. It is the first time that the whole spectrum of advice will be presented in a single publication, which is expected to be published in 2013, following a public consultation process.

Obesity Triples the Radiation Dose of Stone Protocol Computerized Tomography

Patients with recurrent nephrolithiasis are often evaluated and followed with computerized tomography. Obesity is a risk factor for nephrolithiasis. We evaluated the radiation dose of computerized tomography in obese and nonobese adults. We scanned a validated, anthropomorphic male phantom according to our institutional renal stone evaluation protocol. The obese model consisted of the phantom wrapped in 2 Custom Fat Layers (CIRS, Norfolk, Virginia), which have been verified to have the same radiographic tissue density as fat. High sensitivity metal oxide semiconductor field effect transistor dosimeters were placed at 20 organ locations in the phantoms to measure organ specific radiation doses. The nonobese and obese models have an approximate body mass index of 24 and 30 kg/m(2), respectively. Three runs of renal stone protocol computerized tomography were performed on each phantom under automatic tube current modulation. Organ specific absorbed doses were measured and effective doses were calculated. The bone marrow of each model received the highest dose and the skin received the second highest dose. The mean ± SD effective dose for the nonobese and obese models was 3.04 ± 0.34 and 10.22 ± 0.50 mSv, respectively (p <0.0001). The effective dose of stone protocol computerized tomography in obese patients is more than threefold higher than the dose in nonobese patients using automatic tube current modulation. The implication of this finding extends beyond the urological stone population and adds to our understanding of radiation exposure from medical imaging.

Radiological protection from radioactive waste management in existing exposure situations resulting from a nuclear accident.

In environmental remediation after nuclear accidents, radioactive wastes have to be appropriately managed in existing exposure situations with contamination resulting from the emission of radionuclides by such accidents. In this paper, a framework of radiation protection from radioactive waste management in existing exposure situations for application to the practical and reasonable waste management in contaminated areas, referring to related ICRP recommendations was proposed. In the proposed concept, intermediate reference levels for waste management are adopted gradually according to the progress of the reduction in the existing ambient dose in the environment on the basis of the principles of justification and optimisation by taking into account the practicability of the management of radioactive waste and environmental remediation. It is essential to include the participation of relevant stakeholders living in existing exposure situations in the selection of reference levels for the existing ambient dose and waste management.

Commentary on the appropriate radiation level for evacuations.

This commentary reviews the international radiation protection policy that resulted in the evacuation of more than 90,000 residents from areas near the Fukushima Daiichi NPS and the enormous expenditures to protect them against a hypothetical risk of cancer. The basis for the precautionary measures is shown to be invalid; the radiation level chosen for evacuation is not conservative. The actions caused unnecessary fear and suffering. An appropriate level for evacuation is recommended. Radical changes to the ICRP recommendations are long overdue.

A retrospective evaluation of radiation dose associated with low dose FDG protocols in whole-body PET/CT

The objective of the study is to retrospectively measure patient radiation dose resulting from whole body X-ray CT and FDG PET studies using a low-dose protocol performed on the Siemens Biograph mCT scanner. A total of 483 patient studies were reviewed. For each, the CT dose-length product was used to estimate radiation dose to the patient as a result of the whole body X-ray CT component of the PET/CT study. The net injected FDG dose was used to calculate the whole body effective dose based on ICRP recommendations. Dose calculations were also modified to take into account individual patient weight. The total effective dose received by each patient was taken as the sum of the PET and CT components of the study. The mean effective dose from the CT component of the diagnostic study was found to be 8.2mSv (3.4-23.4mSv), for a CT protocol of 120 kV(p) and effective tube current-time product of 80mAs with automatic exposure control. For an average injected FDG activity of 304MBq the mean PET effective dose was found to be 6.3mSv when using the ICRP standard models, or 6.0mSv when scaling effective dose to individual patient weight or patient blood volume. The average total effective dose across the entire patient cohort for a combined PET/CT study was found to be ~14.5mSv (9.6-29.8mSv). Low-dose protocols for whole-body PET/CT scanning result in an effective radiation dose to the patient of approximately 14.5mSv. Additional reductions through the use of iterative CT reconstruction and optimized low-dose FDG protocols could see total effective doses for whole-body PET/CT fall to below 10mSv.

Radiation cataracts: epidemiology and biology

AbstractPurpose The lens is one of the most radiosensitive tissues in the body. Ocular ionizing radiation exposure results in characteristic, dose related, progressive changes leading to cataract formation. While initial, early stages of such opacification may not cause visual disability, the severity of such changes progressively increases with dose until vision is impaired and cataract extraction surgery may be required. The latency of such changes is inversely related to dose. Within the past few months, the ICRP released new guidelines and recommendations concerning ocular ionizing radiation exposure, significantly lowering the presumptive threshold for radiation cataract to 0.5 Gy, regardless of acute, protracted or chronic exposure. Similarly, the occupational lens exposure limit was lowered, from 150 mSv/yr to an average of 20 mSv/yr over 5 years, with no single year exceeding 50 mSv.Methods Recent human epidemiological studies have helped refine radiation cataract risk in various exposed populations. Nevertheless, considerable uncertainties remain concerning the precise pathobiology and the relationship between cataract development, age at exposure, threshold dose and genetic determinants of radiosensitivity.Results Recent findings will be reviewed and new data on the genetic and individual basis of radiation cataract risk will be presented.Conclusion New ICRP recommendations are likely to have significant implications for presumed radiation cataract risk, especially in radiosensitive individuals, as well as the need for occupational eye protection in fields such as interventional medicine. Cellular and molecular pathways leading to radiation cataract have fundamental relevance to that in other tissues and likely involves genomic damage, abberent division and abnormal differentation.