EURADOS Intercomparison 2008 for whole body dosemeters

EURADOS was created to be a scientific network of European laboratories involved in research in radiation dosimetry. The objective is to advance the scientific understanding and the technical development of the dosimetry of ionising radiation by stimulating collaboration between European facilities.

Over the last decade, EURADOS has coordinated the working group on Harmonisation of Individual monitoring in Europe (WG2) entrusting them different tasks along the time. With the aim to improve the harmonization of individual monitoring and help the individual monitoring services (IMS) to comply with ISO 17025 standard, the subgroup 2 (WG2-SG2) was assigned to undertake a feasibility study for a self sustained programme of intercomparisons in Europe.

As a result of this work, EURADOS has organized the EURADOS Intercomparison 2008 for whole body dosemeters.

The intercomparison concerned to whole body dosemeters intended to estimate H_p(10) and/or H_p(0,07)  and used routinely in individual monitoring of exposed workers.

The candidate participants were invited to fill in the Application Form. Invoices were sent out to about 50 candidate participants from 21 European countries, planning to participate with a total of about 60 dosimetry systems. The participants were requested to transfer the participation fee of 1250 Euro per participating dosimetry system to the EURADOS bank account before May 9^th. The fee was calculated on a non-profit base and any surplus money will be used primarily for the purpose of harmonisation in individual monitoring and maintaining the expertise in this field within EURADOS.

For this intercomparison a total of 26 dosemeters from each participant IMS were needed:

1.       20 dosemeters for irradiation

2.       2 transit dosemeters for background control

3.       4 spare dosemeters

The participants were requested to label the dosemeters following the guidelines provided by the Organization Group and sent the dosemeters to the coordinating laboratory (NRG Arnhem, Netherlands).

Irradiations, restricted to photons, have been performed in an European accredited irradiation facility in terms of H_p(10) and H_p(0,07) in the following ranges:

1.       Energy: 30 keV to 1,3 MeV

2.       Dose: 0,2 mSv to 1 Sv

3.       Angle of incidence: ± 60º

After completing the irradiations, the irradiation lab returned the dosemeters to the coordinating laboratory. At the end of August, the coordinating laboratory sent back the dosemeters to the participants for readout. The participants were requested to send back the results in terms of H_p(10) and / or H_p(0,07) in a response form provided by the Organization Group; the deadline was 30 September 2008.

The coordinator then processed the results received from the participants and reported the responses together with the data of the irradiations to the participants as a preliminary report. The participants were given the opportunity to either confirm the data, or to send any questions or remarks.

About 20 participants sent a comment to the Organization Group, some requesting to submit revised participants results, others requesting a review of the irradiation laboratories results. All comments were discussed by the Organization Group at a meeting in November 2008. After consulting the irradiation laboratory, the Organization Group decided not to change any data, except for one case in which the coordinator obviously interchanged the labels of two dosemeters.

A preliminary overview of the results was presented in a meeting that was organized to show and discuss the results among the Organization Group and the participants. This meeting took place coinciding with the EURADOS Annual Meeting 2009 at Braunschweig. At the end of this meeting, EURADOS provided the participants present at the meeting with a “Certificate of Participation” including information on the irradiation qualities and uncertainties, doses imparted and response values. The certificates for the participants not present at the meeting were sent by regular mail.  

The presentations of this meeting:
Intercomparison 2008 whole body dosemeters, Project overview
Dosemeter Intercomparison Exercises
GAEC Ionizing Radiation Calibration Laboratory
Intercomparison 2008 whole body dosemeters, Overview preliminary results
Dosemeter Algorithms
EURADOS Intercomparison 2008 - Film Dosemeters
EURADOS Intercomparison, HPA Personal Dosimetry Service

The Organization Group will prepare a report presenting the final results of the intercomparison. The numerical values of the doses reported by the participants and the irradiation laboratory are fixed as reported in the Certificates of Participation. However options to define outliers, for example by comparison with trumpet curve criteria for photons (ISO-14146), are still under discussion. The report will mention the name of the IMS that participated and the type of dosemeter used but the results will be given anonymously. An overview of participant comments received from the participants will be included in the report.

Intercomparison results will be considered by EURADOS as confidential data and only will be used with statistical purposes for technical and scientific studies. Both the identity of the participants and the reference data will be known only to a minimum of persons within the Organization Group.