The EURAMET #1177 project, identified as EURAMET RI(I) - S9 comparison, was the first EURAMET wide scale supplementary comparison in the field of diagnostic radiology for air kerma area product, PKA, and air kerma, K. It was conducted with the goal of testing the measurement and calibration capabilities for PKA and K, as well as of supporting the relevant CMCs of the participating laboratories. Two commercial KAP meters and an ionization chamber were selected as transfer instruments and circulated between the 22 European participants. The measurements were performed from April 2011 until July 2012. The stability and the performance of the transfer instruments were tested by the pilot laboratory (IRCL/GAEC-EIM) and few other laboratories as well. The test results revealed that the energy (radiation quality), Q, irradiation area, A, and air kerma rate, K̇ dependences of response of the transfer KAP meters influence the comparison of the results when different measurement conditions were pertained and therefore, appropriate correction factors were obtained and applied to the reported calibration results of the laboratories, when necessary. The comparison reference values (CRVs) for each instrument were determined as the weighted mean of the calibration coefficients of the three participating primary laboratories. The relative standard uncertainty of the CRVs were in the range of (0.4 - 1.6)% depending on the transfer instruments and beam qualities. The comparison result as the ratio of the corrected calibration coefficient of participant and the respective CRV, and its uncertainty were calculated for all beam qualities and transfer instruments. The informative degrees of equivalence (DoE) were calculated for the refrence RQR 5 beam quality. In case of air kema area product measurements the results for the RADCAL PDC KAP meter were used. The 216 KAP meter calibration results of the two different transfer instruments in terms of air kerma area product were consistent within 5% except 40 results of 8 participants. The 103 air kerma calibration results were consistent within 1.7%, except 10 results of 4 participants. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The results of an unprecedented international effort involving 26 countries are reported. The EUROMET.RI(I)-K1 and EUROMET.RI(I)-K4 key comparisons were conducted with the goal of supporting the relevant calibration and measurement capabilities (CMC) planned for publication by the participant laboratories. The measured quantities were the air kerma (K-air) and the absorbed dose to water (D-w) in Co-60 radiotherapy beams. The comparison was conducted by the pilot laboratory MKEH (Hungary), in a star-shaped arrangement from January 2005 to December 2008. The calibration coefficients of four transfer ionization chambers were measured using two electrometers. The largest deviation between any two calibration coefficients for the four chambers in terms of air kerma and absorbed dose to water was 2.7% and 3.3% respectively. An analysis of the participant uncertainty budgets enabled the calculation of degrees of equivalence (DoE), in terms of the deviations of the results and their associated uncertainties. As a result of this EUROMET project 813 comparison, the BIPM key comparison database (KCDB) will include eleven new K-air and fourteen new D-w DoE values of European secondary standard dosimetry laboratories (SSDLs), and the KCDB will be updated with the new DoE values of the other participant laboratories. The pair-wise degrees of equivalence of participants were also calculated. In addition to assessing calibration techniques and uncertainty calculations of the participants, these comparisons enabled the experimental determinations of N-Dw/N-Ka ratios in the Co-60 gamma radiation beam for the four radiotherapy transfer chambers.

In the current brachytherapy practice, the procedures to determine the absorbed dose imparted to the patient are affected by an uncertainty higher than in radiotherapy with external beams. That could reduce the success of brachytherapy treatments. Most of the uncertainty is due to a lacking metrology: no absorbed-dose primary standards are so far available to assure direct traceability in dosimetry of brachytherapy sources. This paper outlines the project "Increasing cancer treatment efficacy using 3D brachytherapy", co-funded in the framework of the project iMERA-Plus according to the Grant Agreement No. 217257 between the European Commission and the European Association of National Metrology Institutes. The aim of the project is to develop methods for the direct measurement of the absorbed dose to water and to extend the use of this reference quantity to brachytherapy dosimetry with an uncertainty on the dose delivered to the target volume less than 5% (k=1) at clinical level. The present project will potentially increase the accuracy and safety of brachytherapy to a level comparable to that typical of radiotherapy with external accelerator beams.

This paper outlines the joint research project “Increasing cancer treatment efficacy using 3D brachytherapy” co-funded in the FP7, according to the iMERA-Plus Grant Agreement No. 217257 between the EC and EURAMET e. V. (European Association of National Metrology Institutes). The project brings together the capabilities of ten major European National Metrology Institutes in the ionizing radiation field and it is focused on the targeted programme “Health”. It aims at establishing across Europe a more accurate metrological basis in brachytherapy by developing methods for the direct measurement of the quantity absorbed dose to water in brachytherapy dosimetry with an uncertainty on the dose delivered to the target volume less than 5% (k=1) at clinical level. In fact, in the current brachytherapy practice, the procedures to determine the absorbed dose imparted to the patient are affected by an uncertainty that could reduce the treatment success. Most of this uncertainty is due to a lacking metrology. No absorbed-dose primary standards are so far available to assure direct traceability in dosimetry of brachytherapy sources. In order to optimize the brachytherapy treatments there is also a need for more accurate dosimetry with high spatial resolution. The present research project is expected to increase the accuracy of brachytherapy to a level comparable to that typical of radiotherapy with external accelerator beams.

The effect of different X ray radiation qualities on the calibration of mammographic dosemeters was investigated within the framework of a EUROMET (European Collaboration in Measurement Standards) project. The calibration coefficients for two ionization chambers and two semiconductor detectors were established in 13 dosimetry calibration laboratories for radiation qualities used in mammography. They were compared with coefficients for other radiation qualities, including those defined in ISO 4037-1, with first half value layers in the mammographic range. The results indicate that the choice of the radiation quality is not crucial for instruments with a small energy dependence of the response. However, the radiation quality has to be chosen carefully if instruments with a marked dependence of their response to the radiation energy are calibrated.

The accuracy and traceability of the calibration of radiotherapy dosimeters is of great concern to those involved in the delivery of radiotherapy. It has been proposed that calibration should be carried out directly in terms of absorbed dose to water, instead of using the conventional and widely applied quantity of air kerma. In this study, the faithfulness in disseminating standards of both air kerma and absorbed dose to water were evaluated, through comparison of both types of calibration for three types of commonly used radiotherapy dosimeters at 60Co gamma beams at a few secondary and primary standard dosimetry laboratories (SSDLs and PSDLs). A supplementary aim was to demonstrate the impact which the change in the method of calibration would have on clinical dose measurements at the reference point. Within the estimated uncertainties, both the air kerma and absorbed dose to water calibration factors obtained at different laboratories were regarded as consistent. As might be expected, between the SSDLs traceable to the same PSDL the observed differences were smaller (less than 0.5%) than between PSDLs or SSDLs traceable to different PSDLs (up to 1.5%). This can mainly be attributed to the reported differences between the primary standards. The calibration factors obtained by the two methods differed by up to about 1.5% depending on the primary standards involved and on the parameters of calculation used for 60Co gamma radiation. It is concluded that this discrepancy should be settled before the new method of calibration at 60Co gamma beams in terms of absorbed dose to water is taken into routine use.