The aim of this study is to model plutonium (Pu) excretion from the analysis of a well-documented Pu wound case involving repeated diethylene-triamine-penta-acetic acid (DTPA) perfusions up to 390 d and monitoring up to 3109 d. Three modelling approaches were simultaneously applied involving: (1) release of soluble Pu from the wound, estimated with the ICRP66 dissolution model, (2) systemic behaviour of Pu by using ICRP67 model, but also two new models recently reported and (3) additional 'Pu-DTPA' compartments which transfer Pu directly to urinary compartment from blood, interstitial fluids and liver. The best fit of simulations to biological data was obtained by using the new Leggett's systemic model and assuming the presence of three DTPA compartments. Calculations have shown that DTPA treatments have contributed to a 3-fold reduction of the effective dose. Thus, reduction of doses associated with the DTPA treatments can be estimated by modelling which is useful to improve the efficacy of a DTPA treatment schedule based on a diminution of risk.

RÉSUMÉABSTRACT implication of the occupational physician and of the expert in the management and the dosimetry of an accidental contamination.This case concerns a wound contaminated by plutonium. In managing the consequences of such an incident, the occupational physician of a nuclear installation has to solve various questions in the field of dosimetry, communication and regulation. Dosimetry and risk evaluation of internal contamination are complex. Dose limits are annual limits and it is dificult to explain to the victim that for internal contamination the decision concerning the ability to work in controlled areas is determined on the basis of a commiîted dose on 50 years. Moreover, the notification of such an incident to the employer, to the labour inspectorate and to the govermental organism of control of radiation protection needs an important involvement in the domain of information. This case allows us to describe various practical aspects of medical management and dosimetry. The follow-up of measurements and therapy is given for a period of more than five years.

Use of hair as a biological dosimeter of neutron exposure was proposed a few years ago. To date, the (32)S(n,p)(32)P reaction in hair with a threshold of 2.5 MeV is the best choice to determine the fast neutron dose using body activation. This information is essential with regards to the heterogeneity of the neutron transfer to the organism. This is a very important parameter for individual dose reconstruction from the surface to the deeper tissues. This evaluation is essential to the adapted management of irradiated victims by specialized medical staff. Comparison exercises between clinical biochemistry laboratories from French sites (the CEA and COGEMA) and from the IRSN were carried out to validate the measurement of (32)P activity in hair and to improve the techniques used to perform this examination. Hair was placed on a phantom and was irradiated at different doses in the SILENE reactor (Valduc, France). Different parameters were tested: variation of hair type, minimum weight of hair sample, hair wash before measurement, delivery period of results, and different irradiation configurations. The results obtained in these comparison exercises by the different laboratories showed an excellent correlation. This allowed the assessment of a dose-activity relationship and confirmed the feasibility and the interest of (32)P measurement in hair following fast neutron irradiation.

RÉSUMÉThe use of decision threshold and detection limit concepts often poses many problems for metrologists in biological analysis laboratories in charge of the management of nuclear plant workers. These problems are frequently related to the understanding of a normalized formula or to the possible choice between several formulas whose numerical results are exceptionally significantly different. The true problems are in fact firstly the significance and the interpretation of these statistical tests, and secondly the numerical values used in these tests. Among those, the background estimate remains the essential and the most delicate value to define. The aim of this first article is to go back to the initial bases of the concepts of the decision threshold and detection limit. In the first step, a distinction will be made between the methods of decision threshold determination based upon definition of a priori first species error risks (i.e. before sample measurement) and the a posteriori interpretation of the sample Article publié par EDP Sciences A. VIVIER et al. 322 RADIOPROTECTION -VOL. 45 -N° 3 (2010) measurement result. In the second step, some examples of decision threshold and detection limit optimization in gamma spectrometry will be described. These examples will show that the essential parameter is the optimization of the estimation of background values, which requires the control of measurement rather than the management of statistical tools.