Andrew McWhan

EURADOS self-sustained programme of intercomparisons for individual monitoring services

Within EURADOS working group 2, a system for self-sustained intercomparisons for individual monitoring services for external radiation was developed. With the intercomparison results, the participants can show compliance within their quality management system, compare their results with those from other participants and develop plans for improvement of their system. The costs of the exercises are covered by the participants fees. In this programme, the first intercomparison exercise for whole-body dosemeters has been executed in 2008 with 62 participating dosimetry systems from participants across Europe. In general, film systems show the largest deviations, although the results of some participants indicate that it is possible to achieve results with a film system with similar quality as for thermoluminescence dosimetry (TLD) systems. A second intercomparison has been organised for extremity dosemeters in 2009. For 2010 it is planned to organise a second intercomparison for whole-body dosemeters.

Results of the EURADOS extremity dosemeter intercomparison 2009

This paper presents the results of an intercomparison for extremity dosemeters organised by the European radiation dosimetry group in 2009. In total, 59 systems were tested during this exercise including ring, stall and wrist dosemeters. A total of 1652 dosemeters were irradiated in the selected fields of photons and beta radiation qualities on appropriate phantoms (ISO finger and pillar phantom) in the dose quantity H(p)(0.07). All irradiations were carried out in selected accredited reference dosemetry laboratories (Seibersdorf Laboratories, Austria and IRSN, France). The results show that, especially at low-energy beta radiations ((85)Kr) and for beta irradiations with large angles of incidence (60°), many tested systems show pronounced under responses. On the other hand, for photon irradiations down to energies of 16 keV most systems showed good results. A participants meeting was held at IM2010 with discussion on both general aspects of this intercomparison and specific problems.

EURADOS INTERCOMPARISONS IN EXTERNAL RADIATION DOSIMETRY: SIMILARITIES AND DIFFERENCES AMONG EXERCISES FOR WHOLE-BODY PHOTON, WHOLE-BODY NEUTRON, EXTREMITY, EYE-LENS AND PASSIVE AREA DOSEMETERS

The European Radiation Dosimetry Group (EURADOS) has been organising dosimetry intercomparisons for many years in response to an identified requirement from individual monitoring services (IMS) for independent performance tests for dosimetry systems. The participation in intercomparisons gives IMS the opportunity to show compliance with their own quality management system, compare results with other participants and develop plans for improving their dosimetry systems. In response to growing demand, EURADOS has increased the number of intercomparisons for external radiation dosimetry. Most of these fit into the programme of self-financing intercomparisons for dosemeters routinely used by IMS. This programme is being coordinated by EURADOS working group 2 (WG2). Up to now, this programme has included four intercomparisons for whole-body dosemeters in photon fields, one for extremity dosemeters in photon and beta fields, and one for whole-body dosemeters in neutron fields. Other EURADOS working groups have organised additional intercomparisons including events in 2014 for eye-lens dosemeters and passive area dosemeters for environmental monitoring. In this paper, the organisation and achievements of these intercomparisons are compared in detail focusing on the similarities and differences in their execution.

EURADOS PROGRAMME OF INTERCOMPARISONS FOR INDIVIDUAL MONITORING SERVICES: SEVEN YEARS OF DEVELOPMENT AND FUTURE PLANS

In 2008 the European Radiation Dosimetry Group (EURADOS) started a new programme of intercomparisons for individual monitoring services (IMS). The aim was to provide the possibility to IMS in Europe to participate in dosimetry intercomparions with regular time intervals with all types of dosemeter systems that are used routinely to monitor workers for exposure to external radiation. A self-evaluation of the programme shows that, apart from a few problems encountered, the programme can be judged as fit for its purpose. The results of a questionnaire among the participants support this conclusion. The conclusions encourage EURADOS to continue this programme of self-sustained intercomparisons for IMS.

Different versions of the right answer: the importance of measurement uncertainty in radiation dosimetry.

The performance of radiation dosemeters that are issued by approved individual monitoring services generally meet international standards, with typical results within a few tens of per cent of the reference value. Experienced dosimetry practitioners will understand the uncertainties and treat monitoring results with due caution. However, where different technologies (for example, where passive and electronic dosemeters) are used side by side, apparent disagreements can arise. These apparent disagreements between different systems can be significant, and dosimetrists must be prepared to help in addressing the issues that result.

Intercomparisons for individual monitoring services in Europe: Organization, experience and results

The European Radiation Dosimetry Group (EURADOS) has set-up a worldwide unique program of self-sustainable international intercomparisons for individual monitoring services (IMS). Starting in 2008, with three intercomparisons for whole body photon dosimeters every 2 nd year, one intercomparison in 2009 for photon and beta extremity dosimeters and in 2012, an intercomparison for neutron whole body dosimeters, the intercomparisons became fundamental for the harmonization of radiation protection and individual monitoring in Europe. With the intercomparison results, the participants can show compliance within their quality management system, compare their results with those from other participants and develop plans for improvement of their system. The costs of the exercises are covered by the participants fees. For the whole body photon intercomparisons a the number of participating systems increased from 62 in 2008 to 88 in 2012, showing the big demand for such exercises. Some of the system types like film dosimeters showed decreasing deviations of their results in the general and subsequently increased their quality in the dosimetric performance. The calibration of the systems showed to be an important factor for the performance of all system types. The intercomparison for extremity dosimeters for photon and beta radiation revealed large deviations for quite a few of the participating systems. The intercomparison actions are planned to be continued on a regular basis; the next whole body photon intercomparison is scheduled for 2014. International intercomparisons for IMS for external radiation will bring in improvement and harmonization in individual monitoring.