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International audience; Digital X-ray imaging systems for MeV range photon beams are based on a combination of a scintillator screen and either a camera or an amorphous silicon array. To limit dose rate on electronics and enhance imaging device lifetime, the scintillator screen can be mirror-coupled to the camera. Performances of such devices are a compromise between exposure time and spatial resolution. These technical characteristics are especially scintillator dependent. In this paper, we present, in a first part a performance evaluation of six different scintillators with a 9 MeV Bremsstrahlung X-ray source. The tested scintillators are composed of one micro-structured CsI(Tl) scintillator, two phosphor (GOS) screens and three transparent scintillators. These scintillators present a wide range of density, thickness and conversion efficiency. Each scintillator's performance is assessed based on the combination of light output (ADU number) and modulation transfer function (spatial resolution) obtained. The results are helpful to guide design and engineering of high energy imaging devices adapted to specific requirements. Then, in a second part, we show imaging performance comparison between our actual Gadox screen detector and a new CsI screen detector.

The invention relates to a method for determining the spectral and spatial distribution of a braking photon flow along at least one direction in space (x, y, z), characterised in that the method comprises measuring the neutrons resulting from the impact of the braking photons (ph) on at least one conversion target (5) which is moved in the direction (x, y, z) in space. The invention can be used for X-rays, medical imaging, tomography, etc., L'invention concerne un procédé de détermination de distribution spectrale et spatiale d'un flux de photons de freinage selon au moins une direction de l'espace (x, y, z), caractérisé en ce que le procédé s'effectue par une mesure de neutrons qui résultent de l'impact des photons de freinage (ph) sur au moins une cible de conversion (5) que l'on déplace selon la direction de l'espace (x, y, z). Application à la radiographie, à l'imagerie médicale, à la tomographie, etc.

International audience; This paper presents the progress of an ongoing study within Working Group N°27 of the CETAMA[1] regarding the performances of software used for determining the isotopic composition of plutonium and uranium, by means of γ spectrometry, in the presence of “disturbing” radioactive emitters and of various matrices. The “disturbing” radio-emitters are some minor actinides (242Am, 243Am, 237Np, 243Cm etc.), fission products (137Cs, 125Sb, 154Eu etc.) and/or activation products (60Co etc.). All these radionuclides can be found in waste from the nuclear industry. Matrices can also vary (metal, vinyl…). In some instances, these radionuclides and matrices are in high enough quantities to disturb the analysis by the software for determining the isotopic composition. This paper presents the outline and first achievements of this. [1] The CETAMA (Commission d'Etablissement des Méthodes d'Analyse), part of the CEA, has served laboratories for analysis and monitoring facilities throughout the French nuclear sector. Working group N°27 brings together experts in neutron and gamma spectrometry measurements to identify suitable non destructive assay methods for waste packages of all shapes, all backgrounds and all levels of alpha or beta-gamma emitters.

Lesions of articular cartilage have a large variety of causes among which traumatic damage, osteoarthritis and osteochondritis dissecans are the most frequent. Replacement of articular defects in joints has assumed greater importance in recent years. This interest results in large part because cartilage defects cannot adequately heal themselves. Many techniques have been suggested over the last 30 years, but none allows the regeneration of the damaged cartilage, i.e. its replacement by a strictly identical tissue. In the first generation of techniques, relief of pain was the main concern, which could be provided by techniques in which cartilage was replaced by fibrocartilage. Disappointing results led investigators to focus on more appropriate bioregenerative approaches using transplantation of autologous cells into the lesion. Unfortunately, none of these approaches has provided a perfect final solution to the problem. The latest generation of techniques, currently in the developmental or preclinical stages, involve biomaterials for the repair of chondral or osteochondral lesions. Many of these scaffolds are designed to be seeded with chondrocytes or progenitor cells. Among natural and synthetic polymers, collagen- and polysaccharide-based biomaterials have been extensively used. For both these supports, studies have shown that chondrocytes maintain their phenotype when cultured in three dimensions. In both types of culture, a glycosaminoglycan-rich deposit is formed on the surface and in the inner region of the cultured cartilage, and type II collagen synthesis is also observed. Dynamic conditions can also improve the composition of such three-dimensional constructs. Many improvements are still required, however, in a number of key aspects that so far have received only scant attention. These aspects include: adhesion/integration of the graft with the adjacent native cartilage, cell-seeding with genetically-modified cell populations, biomaterials that can be implanted without open joint surgery and combined therapies, aimed at disease modification, pain relief and reduction of inflammation.Lesions of articular cartilage have a large variety of causes among which traumatic damage, osteoarthritis and osteochondritis dissecans are the most frequent. Replacement of articular defects in joints has assumed greater importance in recent years. This interest results in large part because cartilage defects cannot adequately heal themselves. Many techniques have been suggested over the last 30 years, but none allows the regeneration of the damaged cartilage, i.e. its replacement by a strictly identical tissue. In the first generation of techniques, relief of pain was the main concern, which could be provided by techniques in which cartilage was replaced by fibrocartilage. Disappointing results led investigators to focus on more appropriate bioregenerative approaches using transplantation of autologous cells into the lesion. Unfortunately, none of these approaches has provided a perfect final solution to the problem. The latest generation of techniques, currently in the developmental or preclinical stages, involve biomaterials for the repair of chondral or osteochondral lesions. Many of these scaffolds are designed to be seeded with chondrocytes or progenitor cells. Among natural and synthetic polymers, collagen- and polysaccharide-based biomaterials have been extensively used. For both these supports, studies have shown that chondrocytes maintain their phenotype when cultured in three dimensions. In both types of culture, a glycosaminoglycan-rich deposit is formed on the surface and in the inner region of the cultured cartilage, and type II collagen synthesis is also observed. Dynamic conditions can also improve the composition of such three-dimensional constructs. Many improvements are still required, however, in a number of key aspects that so far have received only scant attention. These aspects include: adhesion/integration of the graft with the adjacent native cartilage, cell-seeding with genetically-modified cell populations, biomaterials that can be implanted without open joint surgery and combined therapies, aimed at disease modification, pain relief and reduction of inflammation.

Lesions of articular cartilage have a large variety of causes among which traumatic damage, osteoarthritis and osteochondritis dissecans are the most frequent. Replacement of articular defects in joints has assumed greater importance in recent years. This interest results in large part because cartilage defects cannot adequately heal themselves. Many techniques have been suggested over the last 30 years, but none allows the regeneration of the damaged cartilage, i.e. its replacement by a strictly identical tissue. In the first generation of techniques, relief of pain was the main concern, which could be provided by techniques in which cartilage was replaced by fibrocartilage. Disappointing results led investigators to focus on more appropriate bioregenerative approaches using transplantation of autologous cells into the lesion. Unfortunately, none of these approaches has provided a perfect final solution to the problem. The latest generation of techniques, currently in the developmental or preclinical stages, involve biomaterials for the repair of chondral or osteochondral lesions. Many of these scaffolds are designed to be seeded with chondrocytes or progenitor cells. Among natural and synthetic polymers, collagen‐ and polysaccharide‐based biomaterials have been extensively used. For both these supports, studies have shown that chondrocytes maintain their phenotype when cultured in three dimensions. In both types of culture, a glycosaminoglycan‐rich deposit is formed on the surface and in the inner region of the cultured cartilage, and type II collagen synthesis is also observed. Dynamic conditions can also improve the composition of such three‐dimensional constructs. Many improvements are still required, however, in a number of key aspects that so far have received only scant attention. These aspects include: adhesion/integration of the graft with the adjacent native cartilage, cell‐seeding with genetically‐modified cell populations, biomaterials that can be implanted without open joint surgery and combined therapies, aimed at disease modification, pain relief and reduction of inflammation

International audience; The effects of MDP, a potent inducer of cytokines, were studied in four batches of Wistar Furth rats with established experimental arthritis. Arthritic rats were given a daily sc injection of 10, 100, 200 or 400 micrograms MDP respectively. Muramyl dipeptide increased the severity of clinical events in a dose-dependent manner, with the exception of the 10 micrograms dose which was ineffective. The levels of anti-collagen antibodies were not however significantly enhanced by MDP. Radiological lesions and histological changes were maximal at high dosage regimens. Paradoxically, the acute phase reactive alpha 1 glycoprotein was little affected by MDP treatment.