Radiosensibilité comparative des cellules épithéliales de trachée de rats après irradiation alpha

La contamination interne par inhalation de radionucléides émetteurs alpha de haut TEL est le risque majeur de l'industrie nucléaire. Les cibles principales de la cancérogenèse pulmonaire sont les cellules épithéliales de l'appareil respiratoire. Une étude in vitro a été menée pour déterminer s'il existe une différence de radiosensibilité aux rayonnement alpha, des cellules épithéliales trachéales de deux souches de rats : Sprague Dawley et Wistar Furth-Fischer F344. Les cellules sont irradiées sédimentées au fond d'un puit spécifique à l'aide de sources électrodéposées de 241Am. L'évaluation de la survie cellulaire en fonction de la dose d'irradiation est complétée par un suivi cinétique de la formation et de la prolifération des colonies

Dynamical substate mixing of fast ions in solids: a density matrix approach

International audienceWe have developed an exploratory model that allows for the temporal evolution of the capture density matrix of a hydrogen-like ion subject to dynamical mixing in solid targets. We show that certain selection rules apply, in effect simplifying the problem to the calculation of reduced (2 × 2) density matrices. This model permits us to extract, from available experimental results, values for the effective wake field and some of the diagonal and off-diagonal capture density matrix elements. Assessment of the approach is discussed in the light of recent experiments

Observation of dynamical substate mixing of fast ions in solids

Using high-resolution x-ray spectroscopy, we have measured, as a function of target thickness, the relative intensities of the fine-structure components of the Balmer α line emitted by fast hydrogen-like krypton ions (33.2 MeV u−1 Kr35+) propagating through thin carbon and copper targets. Our results are in clear disagreement with the predictions of a rate-equation model accounting for collisional l mixing. On the other hand, good agreement is found with a model taking solely into account a wake field-induced Stark mixing of degenerate n, l, j substates. Within this model, the values obtained for the electric field agree well with those deduced from measured total stopping power, which indicates that the effect of core electrons must be considered. Furthermore, off-diagonal density matrix elements of the initial capture process to the n = 3 states are inferred from the experimental intensities. A comparison, for carbon targets, with available (gas-phase) calculations of these matrix elements, reveals important differences

Ionisation en couche K et effet biologique

Les étapes initiales des mécanismes d'effet biologique des radiations sont encore mal connues. La forte corrélation observée entre sections efficaces d'inactivation par ions lourds et sections efficaces d'ionisation K a attiré l'attention sur ce processus. Bien que de faible probabilité, l'ionisation K engendre des grappes d'ionisation très efficaces. Les valeurs de rendement létal extraites des efficacités biologiques relatives mesurées pour les rayonnements X ultra-mous suggèrent une contribution majeure -peut-être dominante- de l'ionisation K à l'effet biologique des ions

Radiation fields, dosimetry, biokinetics and biophysical models for cancer induction by ionising radiation 1996-1999 Biokinetics and dosimetry of incorporated radionuclides. Final report

The final report 'Biokinetics and Dosimetry of Incorporated Radionuclides' presented here is one part of the 5 individual reports. The work to be carried out within this project is structured into four Work Packages: Workpackage 1 concentrates on ingested radionuclides, considering doses to the GI tract and radionuclide absorption. A major objective is the development of a new dosimetric model of the GI tract, taking account of most recent data on gut transit and dose to sensitive cells. Workpackage 2 seeks to improve and extend biokinetic and dosimetric models for systemic radionuclides. Existing models for adults and children will be extended to other elements and new models will be developed for the embryo and fetus. Workpackage 3 is to improve assessment of localised distribution of dose within tissues at the cellular level for specific examples of Auger emitters and alpha emitting isotopes, in relation to observed effects. The work will include experimental studies of dose/effect relationship and the development of localisation methods. Workpackage 4 concerns the development of computer codes for the new dosimetric models, quality assurance of the models and the calculation of dose coefficients. Formal sensitivity analysis will be used to identify critical areas of model development and to investigate the effects of variability and incertainty in biokinetic parameters. (orig.)Available from TIB Hannover: RO 2674(01/00) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLECommission of the European Communities, Brussels (Belgium). Directorate General for Science, Research and Development (DG 12)DEGerman