Key comparison BIPM.RI(I)-K9 of the absorbed dose to water standards of the LNE-LNHB, France, and the BIPM in medium-energy x-rays
A key comparison has been made between the absorbed dose to water standards of the LNE-LNHB, France, and the BIPM in the medium-energy x-ray range. The results show the standards to be in general agreement at the level of the expanded (k = 2) uncertainty of the comparison of 2 parts in 102. The results are presented in terms of degrees of equivalence for entry in the BIPM key comparison database. 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).
First international comparison of primary absorbed dose to water standards in the medium-energy X-ray range
This report presents the results of the first international comparison of primary measurement standards of absorbed dose to water for the medium-energy X-ray range. Three of the participants (VSL, PTB, LNE-LNHB) used their existing water calorimeter based standards and one participant (ENEA) recently developed a new standard based on a water-graphite calorimeter. The participants calibrated three transfer chambers of the same type in terms of absorbed dose to water (N Dw) and in addition in terms of air kerma (NK ) using the CCRI radiation qualities in the range 100 kV to 250 kV. The additional NK values were intended to be used for a physical analysis of the ratios N Dw/NK . All participants had previously participated in the BIPM.RI(I)-K3 key comparison of air kerma standards. Ratios of pairs of NMI's NK results of the current comparison were found to be consistent with the corresponding key comparison results within the expanded uncertainties of 0.6 % - 1 %. The N Dw results were analysed in terms of the degrees of equivalence with the comparison reference values which were calculated for each beam quality as the weighted means of all results. The participant's results were consistent with the reference value within the expanded uncertainties. However, these expanded uncertainties varied significantly and ranged between about 1-1.8 % for the water calorimeter based standards and were estimated at 3.7 % for the water-graphite calorimeter. It was shown previously that the ratios N Dw/NK for the type of ionization chamber used as transfer chamber in this comparison were very close (within less than 1 %) to the calculated values of (μ̄en/ρ)w,a d, the mean values of the water-to-air ratio of the mass-energy-absorption coefficients at the depth d in water. Some of the participant's results deviated significantly from the expected behavior. 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).
Professional tensions in client-centered practice: using institutional ethnography to generate understanding and transformation.
For almost 20 years, occupational therapists have advocated client-centered practice. Yet client-centered practice is fraught with tensions that arise outside the practice of individual occupational therapists. This paper is guided by two questions: What produces professional tensions in client-centered practice? and What understanding and change might be generated using institutional ethnography? The sociological theory and method of institutional ethnography are described using data from an ongoing investigation of mental health services as a social institution. Illustrated are the research aim, research questions, and institutional analysis that distinguish institutional ethnography from conventional ethnography. Two professional tensions are associated with attempts to fulfill client-centered practice in mental health. One is that of working at cross-purposes with the prevailing hierarchical structure; the other tension is that of being celebrated yet subordinated in the medical and management hierarchies of health services. Although client-centered practice is difficult to do, the authors recommend institutional ethnography as a research approach to generate understanding and transformation of the context and practice of occupational therapy.