Report on EUROMET.RI(I)-K1 and EUROMET.RI(I)-K4 (EUROMET project no. 813): Comparison of air kerma and absorbed dose to water measurements of ^sup 60^Co radiation beams for radiotherapy

• Published in: Metrologia 2010-01, p.1
• Main Authors: Csete, I, Leiton, A G, Sochor, V, Lapenas, A, Grindborg, J-E, Jokelainen, I, Bjerke, H, Dobrovodsky, J, Megzifene, A, Hourdakis, C J, Ivanov, R, Vekic, B, Kokocinski, J, Cardoso, J, Buermann, L, Stucki, W, van Dijk, E, Toni, M P, Minniti, R, McCaffrey, J P, Silva, C N M, Kharitonov, I, Webb, D, Saravi, M, Delaunay, F
• Format: Article
• Language: English
• Subjects: Calibration; Comparative analysis; Gamma rays; Radiation therapy; Uncertainty
• ISSN: 0026-1394; 1681-7575

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...) and the absorbed dose to water (D...) in ...Co 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... and fourteen new D... 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.../N... ratios in the ...Co gamma radiation beam for the four radiotherapy transfer chambers. (ProQuest: ... denotes formulae/symbols omitted.)