Establishment of a 241Am gamma calibration field based on international standards and its conversion coefficients.

A 241Am gamma (γ)-ray calibration field that meets the requirements for a γ-ray reference field as specified in the ISO 4037 standard series was established in the Facility of Radiation Standards of the Japan Atomic Energy Agency. The reference air kerma rates were measured using a reference ionization chamber calibrated by the N-80 quality X-ray calibration field of the national metrology standard in Japan and with a correction to account for differences in photon energy due to the calibration field. Conversion coefficients for the 241Am γ-ray calibration field, including those not listed in the ISO 4037 standard series, were calculated based on the measured γ-ray fluence rate spectra.

A fast correction method of the scattering contributions in the area gamma dosemeter calibration field.

In the calibration procedure of area gamma dosemeters, how to accurately evaluate and correct the scattering contribution from the complex environmental factors to the point of test is the key problem to ensure the calibration accuracy. This paper proposed a fast correction method of the scattering contributions in the area gamma dosemeter calibration field. First, Monte Carlo method is employed to simulate the influence of scattering caused by different environmental factors in the calibration field, which is named as semi-panoramic reference radiation field. Then, a prediction model of the relationship between environmental factors and environmental scattering contribution is constructed based on the simulation data through the least squares support vector machine. With the model, the scattering contribution from the environmental factors can be fast estimated to correct the calibration results of the area gamma dosemeters, which will improve the accuracy of the calibration.

The internal dosimetry user group position statement on molecular radiotherapy.

The Internal Dosimetry User Group (IDUG) is an independent, non-profit group of medical professionals dedicated to the promotion of dosimetry in molecular radiotherapy (www.IDUG.org.uk). The Ionising Radiation (Medical Exposure) Regulations 2017, IR(ME)R, stipulate a requirement for optimisation and verification of molecular radiotherapy treatments, ensuring doses to non-target organs are as low as reasonably practicable. For many molecular radiotherapy treatments currently undertaken within the UK, this requirement is not being fully met. The growth of this field is such that we risk digressing further from IR(ME)R compliance potentially delivering suboptimal therapies that are not in the best interest of our patients. For this purpose, IDUG proposes ten points of action to aid in the successful implementation of this legislation. We urge stakeholders to support these proposals and ensure national provision is sufficient to meet the criteria necessary for compliance, and for the future advancement of molecular radiotherapy within the UK.

Effective Dose Coefficients for Intakes of Uranium Via Contaminated Wounds for Reference Adults.

ABSTRACT: Effective dose coefficients for intakes of uranium radionuclides via contaminated wounds have been calculated for reference adults following the procedures in the ICRP 103 series. The number of transformations in each source region for all members of the radioactive series from time of intake to 50 y post intake are calculated by coupling the NCRP 156 wound model to the ICRP 137 systemic models and ICRP 100 human alimentary tract model. Together with the ICRP 107 nuclear decay data for dosimetric calculations, the ICRP 133 specific absorbed fractions are implemented to calculate the radiation-weighted S coefficient deposited in each target organ or tissue from each transformation in each source region. Effective dose coefficients for different categories of intake materials via contaminated wounds are calculated for the three major uranium isotopes-238U, 235U, and 234U. Originating from the combined effects of the new absorbed fractions, biokinetic and dosimetric models, the new coefficients are generally reduced by a percentage of 23-28% as compared to the old ones. The new dose coefficients benefit the assessment of internal exposures for intakes of uranium via contaminated wounds in actual applications.

Trend of strengthening clearance regulation in Japan and concerns about its worldwide effects on regulations for natural and artificial radionuclides.

The Nuclear Regulation Authority (NRA) of Japan invited comments from the public on a revised guide on measurement and evaluation for clearance in 2019, which included a strict decision on how to treat uncertainties in the measurement and the nuclide vector. To resolve the issue on the uncertainty in clearance, a probabilistic approach had been established previously in the Atomic Energy Society of Japan Standard and incorporated into International Atomic Energy Agency (IAEA) Safety Report No. 67. NRA's new decision on the uncertainty in clearance was up to 10 times stricter than the probabilistic approach. This issue has been discussed at an international level in the framework of the ongoing revision of IAEA Safety Guide RS-G-1.7. This discussion on the uncertainty in clearance has raised serious concerns about its effects on other radiological protection regulations worldwide. This is because if we need strict treatment for the uncertainty in clearance, the same or even stricter treatment for conformity assessment may have to be applied to other radiological protection criteria for doses exceeding 10 µSv year-1. Radiological protection experts including regulators, professionals, and operators should be aware of the essential meaning of the radiological protection criteria by considering the background scientific basis on which they were established.

Guidance Needed for Continued Employment of Long-term Contaminated Individuals.

Operational practices in nuclear power utilities often restrict job assignments for workers with internal contamination due to the difficulty of monitoring for new intakes and strict radioactive material controls. However, restriction of job assignments for an extended period (i.e., months to years) may be too conservative. An industry consensus on guidance in these conditions would be helpful for Radiation Safety Officers (RSOs) to allow long term contaminated workers to have less work restrictions.

ICRP recommendations on radon.

The International Commission on Radiological Protection (ICRP) publishes guidance on protection from radon in homes and workplaces, and dose coefficients for use in assessments of exposure for protection purposes. ICRP Publication 126 recommends an upper reference level for exposures in homes and workplaces of 300 Bq m-3. In general, protection can be optimised using measurements of air concentrations directly, without considering radiation doses. However, dose estimates are required for workers when radon is considered as an occupational exposure (e.g. in mines), and for higher exposures in other workplaces (e.g. offices) when the reference level is exceeded persistently. ICRP Publication 137 recommends a dose coefficient of 3 mSv per mJ h m-3 (approximately 10 mSv per working level month) for most circumstances of exposure in workplaces, equivalent to 6.7 nSv per Bq h m-3 using an equilibrium factor of 0.4. Using this dose coefficient, annual exposure of workers to 300 Bq m-3 corresponds to 4 mSv. For comparison, using the same coefficient for exposures in homes, 300 Bq m-3 corresponds to 14 mSv. If circumstances of occupational exposure warrant more detailed consideration and reliable alternative data are available, site-specific doses can be assessed using methodology provided in ICRP Publication 137.

Operational intervention levels for enabling the transition from an emergency exposure situation to an existing exposure situation following a radiological emergency involving release of radioactive material in the environment.

Experience has demonstrated lack of preparedness at national levels to manage the consequences of a nuclear or radiological emergency in its later phase which, on occasions, resulted in unjustified actions. To assist Member States preparing for this phase, the International Atomic Energy Agency (IAEA) published guidance (IAEA Safety Standards Series No. GSG-11) recommending, inter alia, for operational intervention levels (OILT) to be developed for enabling the transition from an emergency exposure situation to an existing exposure situation. OILT are intended to also support decisions be made on lifting or adapting public protective actions imposed early in the emergency response and on actions to be taken to further reduce exposures. Using the methodology provided therein, OILT have been calculated for radiological emergencies involving release of the most commonly used alpha, beta and gamma emitting radionuclides in the environment. In addition, an approach for deriving a default OILT value has been presented and a default OILT value for the ambient dose equivalent rate at 1 m above ground level has been derived. The derived OILT values support the application of relevant IAEA safety standards (i.e. No. GSR Part 7 and No. GSG-11) as well as relevant recommendations of the Council Directive 2013/59 in relation to the transition from the emergency exposure situation to an existing exposure situation at national levels. However, they need to be integrated within the national protection strategies to guide the implementation of activities and actions that support the resumption of normal social and economic activity after the emergency which include those concerning return of members of the public, who were resettled during the implementation of evacuation or relocation, to their homes.

A Comprehensive CT Radiation Dose Reduction and Protocol Standardization Program in a Complex, Tertiary Hospital System.

PURPOSE: To present our experience in reducing CT radiation doses in a complex tertiary health system through CT protocol standardization and optimization. METHODS: A CT radiation task force was created to reduce CT protocol heterogeneity and radiation doses. Redundant protocols were eliminated. By an iterative process, protocols with least radiation dose were identified. Radiation dose tracking software was used to store and analyze radiation doses. CT protocols were published in an intranet site after training of technologists. SOPs were established for maintaining and changing protocols. The radiation doses for each CT protocol before and after optimization were compared using geometric means. RESULTS: A total of 222 CT protocols were reviewed, with elimination of 86 protocols. One-year follow-up showed homogeneous protocols with lower radiation doses. The improvement in radiation doses ranged from 23% to 58% (P< 0.001). CONCLUSION: CT radiation dose reduction of up to 58% can be achieved by homogenizing and optimizing CT protocols through a comprehensive CT operations program.

The role of a commercial radiation dose index monitoring system in establishing local dose reference levels for fluoroscopically guided invasive cardiac procedures.

PURPOSE: The primary goal was to evaluate local dose level for fluoroscopically guided invasive cardiac procedures in a high-volume activity catheterization laboratory, using automatic data registration with minimal impact on operator workload. The secondary goal was to highlight the relationship between dose indices and acquisition parameters, in order to establish an effective strategy for protocols optimization. METHODS: From September 2016 to December 2018, a dosimetric survey was conducted in the 2 rooms of the catheterization laboratory of our institution. Data collection burden was minimized using a commercial Radiation Dose Index Monitoring System (RDIMs) that analyzes dicom files automatically sent by the x-ray equipment. Data were combined with clinical information extracted from the HIS records reported by the interventional cardiologist. Local dose levels were established for different invasive cardiac procedures. RESULTS: A total of 3029 procedures performed for 2615 patients were analyzed. Median KAP were 21 Gycm2 for invasive coronary angiography (ICA) procedures, 61 Gycm2 for percutaneous coronary intervention (PCI) procedures, 59 Gycm2 for combined (ICA+PCI) procedures, 87 Gycm2 for structural heart intervention (TAVI) procedures. A significant dose reduction (51% for ICA procedures and 58% for PCI procedures) was observed when noise reduction acquisition techniques were applied. CONCLUSIONS: RDIMs are effective tools in the establishment of local dose level in interventional cardiology, as they mitigate the burden to collect and register extensive dosimetric data and exposure parameters. Systematic review of data support the multi-disciplinary team in the definition of an effective strategy for protocol management and dose optimization.

Radon Exposures of Miners at Small Underground Construction Sites in Old Mining: Recommendations to Improve Radiation Protection Measures by the Saxon Radiation Protection Authority.

The Ore Mountains (Erzgebirge) and Vogtland are low-mountain regions in the East German state of Saxony. Here, silver deposits were found in 1168. Mining began shortly after, continues at varying intensity to this day, and has left numerous galleries and shafts. Today, eight companies with about 250 miners carry out maintenance at more than 40 small and frequently changing underground construction sites throughout the year. Miners are protected against high radon exposure by radiation protection measures such as ventilations, stoppings made of wood, foil, and expanding foam, and staff rotations. However, some of them still show high annual exposure levels; for example, in 2015 up to 14.4 mSv measured by passive radon dosimeters. Reasons for this include the high radon potential in old mining and the natural density driven mine air current through the galleries. Mine air currents can change directions during the day depending on outdoor temperatures. This paper presents the experiences of the Saxon Radiation Protection Authority in monitoring miners in old mining. For this purpose, the paper looks at seven examples of miners' critical exposures based on measurement curves of radon activity concentration and derives respective radiation protection measures. These encompass, for example, to activate mine fans, erect stoppings, extend ventilation pipes, and change the locations of mine fans. Conclusions are drawn for the operative and strategic radiation protection in old mining.

RAMESIS PROJECT: COLLABORATION WITH SCHOOLS AND INSTITUTIONS ON THE BUILDING OF A CITIZEN MONITORING NETWORK.

In a radiation emergency situation, including its post-emergency recovery phase, substantial needs for radiation measurements can be expected. In such situations, responsible authorities might not be able to satisfy all requirements for measurement. Therefore, involvement of local communities is desirable. Citizen radiation monitoring networks, established in advance as citizen science structures, can serve as a knowledge basis for later participation in self-help protective actions. The article describes the progress of citizen radiation monitoring networks being established in the Czech Republic in the frame of Radiation Monitoring Network for Institutions and Schools project. During the project launch, it has been shown that conducting radiation measurements and results processing have educational effect on students and enhance awareness among interested groups in the field of radiation protection and radiation in general. This article describes the socially oriented part of the project.

SUPPORT TO CITIZEN RADIATION MONITORING OF RADIOACTIVITY IN THE CZECH REPUBLIC-PROJECT RAMESIS.

Project 'RAMESIS', solved by SURO+UTEF+NUVIA, is aimed at the improvement of population safety through supporting Citizen Monitoring in Czechia. Radiation monitoring system at the level of institutions, schools and citizens will be developed and implemented, covering equipment for both fixed-site and mobile monitoring using simple-designed and easy-to-operate detectors, enabling their usage by public and mass-production at acceptable price. The instrumentation includes central application for reception, storage, administration and publication of monitoring results analyzed and presented on web-portal, tools for user's local online and offline data visualization on a map background, and web portal providing training and informational materials for understanding radiation problems. The system will be implemented in selected institutions and schools, initial sets of detectors are distributed free of charge among schools, institutions and the public. This article describes the technical part of the project, solved in the framework of Ministry of Interior-founded security research ID VI20152019028.