[en] In the context of nuclear imagery research the LETI is studying neutron, X-ray and γ-ray localisation detectors, the fields of application being neutron diffraction, X-ray diffraction and nuclear medicine. This report deals only with gas localisation methods, describing the physical results obtained in neutron and X-ray diffraction

[en] A proportional detector for the localization of particles comprises a leak-tight chamber filled with fluid and fitted with an electrode of a first type consisting of one or more conducting wires and with an electrode of a second type consisting of one or more conducting plates having the shape of a portion of cylindrical surface and a contour which provides a one-to-one correspondence between the position of a point of the wires and the solid angle which subtends the plate at that point, means being provided for collecting the electrical signal which appears on the plates. 12 Claims, 10 Drawing Figures

[en] A new important step has been made in the performances of the time-of-flight positron imaging for the two last years. It has been proved that a high spatial resolution can be obtained with the T.O.F. technique. It has also been shown that the overall sensitivity (taking into account the sensitivity gain and BaF2 detection characteristics) is quite close to the one of conventional methods. On the other hand, the basic advantages related to the high counting rate capability, the random coincidences rejection etc... of course remain. It is probably safe to assume that significant improvements can be expected if new technological efforts are invested. Unfortunately, P.E.T. is a complex and expensive tool which has been only used up to now in the research groups (about 50 centers in the world). The justification of new technical developments will be quite clear when this modality will be considered in the assessment of diseases and in clinical diagnostic applications

No abstract available

[en] A competition is arising between C.T. and NMR in the field of medical diagnostic imaging, and it is clear that the medical community interest is presently focused on NMR imaging. Nevertheless, it appears reasonable to assume that the clinical interest of C.T. for different pathologies is remaining. As long as this statement is confirmed, new technical advances can be expected in the near future in order to improve the main characteristics which are: the density resolution, the spatial resolution and the X-ray exposure time. Since only the technological aspects are concerned in this paper, the major advances can be expected in the field of photons flux production and detection. C.T. requires very stringent demands on X-ray tubes. Special tubes have already been developed for that application but further improvements are needed for high spatial resolution multislice machines. Multilinear array of detectors seems to be the major technological advance to accomplish in the near future in order to significantly improve the image quality, and to reach a true three-dimensional imaging

No abstract available

[en] Material for scintillators, application to the construction of very fast, high energy photon detectors and to the construction fo tomographs. The material for scintillators is constituted by barium fluoride which, under excitation, is subject to light emission having a slow component with a maximum centered on 3200 A and a fast component with a maximum centered on 2250 A, the barium fluoride being purified so as to reduce the defects of its crystal lattice, in order to reinforce the intensity of the fast component of its light emission

[en] The present invention relates to an X-ray detector adapted to detect rays having passed through an object or an organ. This detector comprises at least one main tight chamber containing a gas ionizable by X-ray and, in this chamber, a plate for collecting the charges resulting from ionization of the gas. It comprises a secondary ionization chamber, coupled to the main chamber to compensate the scattering current

[en] The present invention relates to a portable radiation measuring device, comprising a detector adapted to deliver electrical signals whose amplitude spectrum depends biunivocally on the energy spectrum of a radiation which may be received by the detector, amplification means and electronic means for compensating the sensitivity of the detector as a function of the energy so as to render it identical to that of human tissues, producing an output signal which is in a constant ratio with the energy of said radiation which may be absorbed by human tissues and display means, connected to the amplification and compensation means, for displaying the dose of radiation received by the detector

[en] The present invention is aimed at improving the random access time to a stimulable radioluminescent screen point (and consequently the reading time of the screen image); it is noticeably useful for longitudinal tomography. The reading device contains a source emitting a stimulation radiation beam towards the stimulable radioluminescent screen, a control mean of the stimulation radiation beam and a deflection mean which allows the beam to scan the screen surface. The device is characterized by the use of a very fast acousto-optical type deflection mean