First EURADOS intercomparison exercise of eye lens dosemeters for medical applications

Transcription

1 First EURADOS intercomparison exercise of eye lens dosemeters for medical applications I. Clairand 1, M. Ginjaume 2, F. Vanhavere 3, E. Carinou 4, J. Daures 5, M. Denoziere 5, E. Honorio da Silva 3, M. Roig 2, S. Principi 2, L. Van Rycheghem 1. 1 Institute for Radiological Protection and Nuclear Safety (IRSN), France 2 Universitat Politècnica de Catalunya (UPC), Spain 3 Belgian Nuclear Research Centre (SCK-CEN), Belgium 4 Greek Atomic Energy Commission (GAEC), Greece 5 CEA-LIST Laboratoire National Henri Becquerel (CEA-LNHB), France

2 Introduction Context: decrease of the eye lens dose limit for occupational exposure to 20 msv/year (European Directive 2013/59/EURATOM) EURADOS: organisation of an intercomparison exercise for eye lens dosemeters in the medical field Main objective: to assess the capabilities of the eye lens dosemeters currently in use in Europe. 2/18

3 Project phases and time schedule Phase Date Preparation Dec February 2014 Selection of participants March 2014 Execution April 2014 January 2015 Reception of dosemeters by coordinating laboratory June 2014 Irradiations July-August 2014 Irradiated dosemeters sent to the participants September 2014 Results reported by the participants October 2014 First draft individual result datasheets sent to participants January 2015 Interpretation of results and reporting February 2015 May 2015 FINAL individual result datasheets + certificates of attendance Under preparation 3/18

4 Eye lens dosemeter types included in this intercomparison A total of 20 European individual monitoring services from 15 different countries were registered. The dosemeters provided by the participants were all composed of thermoluminescent detectors, of various types and designs. SCK- CEN Belgium SURO Czech Republic GAEC Greece U.O.Fisica e Tecnologie Biomediche Italy Lithuanian Radiation Protection Center Lithuania IFJ Poland NIOM Poland SMU Slovakia RPI Ukraine 4/18

5 Eye lens dosemeter types included in this intercomparison IRSN, France AV-Controlatom, Belgium DOSILAB, Switzerland 5/18

6 Eye lens dosemeter types included in this intercomparison DOZIMED S.R.L., Rumania PHE, UK ENEA, Italy Seibersdorf labor GmbH, Austria 6/18

7 Eye lens dosemeter types included in this intercomparison UPC, Spain Tecnorad s.u.r.l., Italy Univ. Hospitals Birmingham, UK VINCA, Serbia 7/18

8 Radiation qualities and doses imparted Setup Radiation quality Ref. Mean energy Nb of irr. dosemeters Range H p (3) (msv) 1 S-Cs; 0 ISO kev S-Cs; 0 ISO kev S-Cs; 60 ISO kev N-40; 0 ISO kev N-60; 0 ISO kev N-80; 0 ISO kev RQR6; 0 IEC kev RQR6; 45 IEC kev RQR6; 75 IEC kev Realistic field (scattered field in int. rad.) CONRAD/ORAMED European projects (PCRD 7) 45 kev /18

9 Irradiations Irradiations were performed according to ISO 4037 standard in terms of personal dose equivalent H p (3) The head phantom (ORAMED design - 20*20) was used Irradiation laboratories UPC - Spain SCK-CEN - Belgium CEA - France IRSN - France For realistic configuration (scattered field in interventional radiology): head phantom was located in the scattered field, reference in H p (3), the scattered radiation produced by the patient was done with an ISO phantom. 9/18

10 Transit dose control/background/spare For each participant: 12 dosemeters were reserved for transit dose correction (3 dosemeters were dispatched to the 4 irradiation laboratories), this correction was made by the organisers. The background correction was made by participant according to the laboratory routine procedure. 6 dosemeters were reserved as spare in order to be used by the irradiation labs in case of damage or errors with the irradiations. Only a very few dosemeters had to be used for this purpose. 10/18

11 Results The numerical results in this intercomparison are reported as the dosemeter response R, where R is defined as R = H p (3) participant corrected for background and transit dose / H p (3) reference For the analysis of the global results, the performance limits according to ISO14146 («trumpet curves») were adopted: R is the response, the ratio between the participant measured value and the conventional true value F = 1.5 (ICRP 75) H C is the conventional true value, in this case, H p (3) reference H 0 : was chosen equal to msv for all participants, assuming a lower limit of the dose range for which the system has been approved of 1 msv in a year, and an issuing frequency of 12 per year, in order to be consistent with the EURADOS report EURADOS Intercomparison 2008 for Whole Body Dosemeters in Photon Fields EURADOS Report /18

12 Individual result datasheet First draft results sent in February Participants were asked: to confirm the results or if they considered that corrections should be made because of errors made by the organization group, to indicate what should be corrected and why. The organization group decided on the corrections on an individual basis. Final results + certificate of attendance: under preparation 12/18

13 Results Among the 20 participants: GENERAL COMMENTS 14 have 100% data within the trumpet curves for all setups, 17 have 90% data within the trumpet curves, 1 is out of the limits for setups with low energies, 3 are out of the limits for setups with large angles, 2 are out of the limits for both types of setup (low energies and large angles). 13/18

14 Calibration: general comments CALIBRATION ENERGY 9 participants use pure S-Cs, 3 participants use mixed S-Cs and X-ray, 8 use various X-ray spectra. CALIBRATION QUANTITY 16 participants use H p (3), 2 participants use H p (10), 2 participants use H p (0.07). PHANTOM USED FOR THE CALIBRATION 10 participants use a cylindrical phantom (20x20) (ORAMED design), 1 participant use a smaller cylindrical phantom (d=16 cm), 7 participants use ISO slab phantom, 1 participant uses the head of Rando phantom, 1 participant uses rod phantom. 14/18

15 Results R = H s /H c S-Cs, 0º, Low S-Cs, 0º, High S-Cs, 60º N-40, 0º N-60, 0º N-80, 0º RQR 6, 0º RQR 6, 45º RQR 6, 75º Realistic field H c (msv) 15/18

16 Results irradiation setups 2,5 Box plots showing the minimum, 1 st quartile, median, 3 rd quartile and maximum responses per irradiation setup 2 1,5 Response 1 0,5 0 S-Cs, 0, Low S-Cs, 0, High S-Cs,60 N-40, 0 N-60, 0 N-80, 0 RQR6, 0 RQR6, 45 RQR6, 75 Realistic field 16/18

17 Results - participants Box plots showing the minimum, 1 st quartile, median, 3 rd quartile, maximum values for each participant. 17/18

18 Conclusion A first European intercomparison exercise of eye lens dosemeters. This intercomparison gives an interesting overview of the different dosimetric systems available in Europe for eye lens dose monitoring. Results are satisfactory (some problems observed for large angles and low energies) Some participants could improve the performance of their system by improving their calibration. A larger eye lens dosemeter intercomparison should be organised by EURADOS in the future. 18/18

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