Other

Biospace Instruments

Agence Nationale De Valorisation De La Recherche (anvar)

Agence Nationale De Valorisation De La Recherche

Eos Imaging

Georges Charpak

Jacques Lewiner

Pascal DeSaute

Wafa Skalli

David Mitton

Ioannis Giomataris

Fabio Sauli

Irène Dorion

Armando Policarpo

Jean-Pierre Robert

Elie Pollak

N'Guyen N Hoan

Hoan N Ngoc

Philippe Rebourgeard

Champlain Landry

Stéphane Veron

High-resolution position detector for high-flux ionizing particle streams

A high resolution radiographic imaging device for medical or industrial radiography includes at least one ionizing particles detector equipped with at least one gas chamber provided with a window for the lateral or frontal inlet of the illumination beam. A first, a second and a third flat electrode are placed in parallel with one another in order to form a conversion space and a amplification space with the distance separating the second and third electrodes being less than 200 .mu.m and the amplitude ratio of the electrical fields created between the second and third electrodes and the first and second electrodes being greater than 10.

High resolution radiographic imaging device

The invention relates to a medical imaging device using X or gamma ionizing radiation. It comprises a source (S) of radiation in a divergent beam, and a longitudinal slit (F) delivering a sheet-form beam in a plane containing the slit (F). A detection module (1) is provided, which comprises a drift chamber (12) and a multiwire chamber which are filled with a gas. The chambers comprise, in a direction orthogonal to the plane containing the slit (F), the drift space (12) for the electrons, comprising a cathode electrode (11), a converter (121), a proportional multiplier anode (13) for generating multiplied electrons and corresponding ions, and a second cathode electrode (14), placed in the vicinity of the multiplier anode (13). The multiplier anode (13) and the second cathode electrode (14) consist of conductor elements extending in two parallel planes, along substantially orthogonal directions, in order to permit two-dimensional localization of the electrons in this plane.

Medical imaging devices using low-dose X or gamma ionizing radiation

A device for forming images of ionizing particles through single-dimensional electrophoresis provided with a multi-wire proportional chamber. The chamber filled with a gas is of asymmetric structure and is formed successively by an entry window for the particles, taken to a negative potential, a multi-wire anode electrode, taken to a potential positive with respect to a reference potential, and a cathode electrode which is placed in the vicinity of the anode electrode. The cathode electrode, which is taken to the reference potential, is formed by a network of parallel electrically conducting strips. Detection of the position of impact of the ionizing particle along the pitch of the network is performed by induction of a delayed electric pulse caused by an avalanche of the ionization electrons issuing from the ionizing particle in the region of the strip situated in line with the impact by the particle in the chamber, the reference time being that of the ionization electrons close to the wires.

Device for forming images of ionizing particles by means of a multi-wire

A medical imaging device using X- or gamma ionizing radiation, provided with a source of radiation in a divergent beam diaphragmed by a slit and a module for detecting a beam transmitted by a body to be observed, illuminated by the beam. The detection module comprises a drift chamber and a multiwire chamber which are filled with a gas, these chambers comprising, in a direction orthogonal to the plane containing the slit and the illumination beam, a drift space for the electrons, an electron proportional multiplier grid for generating multiplied electrons and corresponding ions and a second cathode electrode making it possible to count the multiplied electrons by means of the corresponding ions for a plurality of directions of the sheet-form illumination beam.

Medical imaging device using low-dose X- or gamma ionizing radiation

A method for representing the spatial distribution of radioactive elements of radioactively labeled samples, by means of a screen of the erasable phosphor type, in which the labeled samples are placed near this screen in order to generate thereon a latent electronic image formed by the .beta. radiation or primary electrons generated by the radioactive elements. The primary electrons emitted by the radioelements are accelerated to an energy level lying between 20 keV and 1 MeV by means of an electric field E applied between the space separating the sample and the screen. The primary electrons subjected to acceleration in the space are confined, so as to limit the lateral excursion of these primary electrons. The latent image is formed, on this screen, from the confined and accelerated primary electrons. The primary electrons can generate low energy secondary electrons in CSI screens which are thus accelerated and focussed to give enlarged images onto a screen.

Method for representing the spatial distribution of radioactive elements

Gas ionizing-radiation detector

A device according to the invention includes: a gas detector, comprising at least one chamber (2) and containing a noble gas and a gas or vapor that emits photons between two parallel electrodes (3a, 3b) between which a continuous high voltage (HT) is applied, whereby a first electrode (3a) is intended for receiving, against its external face, the surface of the radioactive body (5,6) to be observed; a brilliance amplifier (13) arranged for receiving the photons emitted by the excited atoms which are produced in the vicinity of a second electrode (3b) by the electron avalanche ascribable to the electrical field between the first and second electrodes; a camera (12) arranged behind the brilliance amplifier; and computing means (15) capable of computing, from the output signal of the camera, the entrance points (9) in said gas detector, at the first electrode, of the electrons emerging from said surface of the radioactive body.

Process and device for determining the spatial distribution of electrons

A method and device are disclosed for determining the distribution of the .beta. rays emerging from a surface. The device comprises an enclosure (3) filled with a gas mixture having a first preamplification chamber (6) between two grids (9 and 10), a second transfer chamber (7) between two grids (10 and (11) and a third multiplication chamber (8) between two grids (11 and 12); as well as three DC voltage sources (13, 14 15); and an impeding assembly (22, 23, 17, 18, 19, 20 and 21).

Method and device for determining the distribution of .beta.rays

For displaying 'electric' images recorded in the form of charges (+) on a dielectric sheet (1), this sheet is surrounded by two electrodes (2,3) one (3) of which is transparent, on the face of this latter turned towards the dielectric sheet is provided a layer (4) of an electroluminescent material held spaced at a small distance from said sheet, this sheet is caused to vibrate perpendicularly to itself (arrows F) and the image developed at the level of the layer (4) by the alternating electric charges generated by the vibrating charges is recorded on a photographic support (5).

Devices for making electric charge images visible

The invention relates to a device for reading the quantities of electrical charges borne by a dielectric sheet using a probe scanning the charged surface of the sheet and connected to an electronic circuit adapted to measure the quantities of charges induced on said probe. This electronic circuit comprises an operational transimpedance amplifier and an analog integrator reset to zero periodically by suitable circuitry.

Devices for reading the quantities of electrical charges borne by a

In order to read-out and reproduce as a visible image the electric charge distribution carried by a dielectric sheet, and formed by the impact of X-rays having traversed a body to be analyzed, one has recourse to a detecting probe (2) out of center with respect to the axis of a head carrying the probe, the head being put in rotation at a high speed (for instance at 6,000 turns/minute), by a small turbine, the axis of the head being displaced relative to the surface of the sheet, parallel to the sheet along two perpendicular directions X and Y in such a way that the probe scans the sheet along a trajectory (T) which has the form of a circle the center of which is subjected to a transverse translation. The read-out can be made very rapidly and leads to a good signal/noise ratio. This allows the use of low irradiation doses for the object to be analyzed. Means can be used to compensate for variations of distance between the probe and the sheet.

Read-out devices of electric charge distributions on dielectric surfaces

In order to measure the values of the electrical charges (2) carried by a surface S of a dielectric sheet (1), one uses a device consisting of a first electrode or probe (S) facing the surface S, a second electrode (4) applied against the back surface of this sheet, means (F) to displace laterally the probe with respect to the sheet and means (5) to measure the charges (6) induced on this probe. In addition, by means of acoustical, optical or electrical methods, one subjects the surface S to deformation localized in very small spots p (of an area inferior to the one defining the spatial resolution of the measurement) during very short times and repeatly at frequence high enough and in such a way as to have some overlapping of the spots sequentially deformed.

Devices designed to measure locally the electric charges carried by

A gas scintillation proportional counter, with a photosensitive layer, is coupled, through a UV transparent window, to a multi-anode proportional chamber filled with a gas mixture (for instance an argon triethylamine-methane mixture) having a large quantum efficiency for the UV photons. When detecting incident photons, there is obtained the good efficency of photosensitive layers and the satisfactory two-dimensional coordinate localization of multiwire proportional chambers.

Detection and imaging of the spatial distribution of visible or

The spatial distribution of mono-energetic x-rays from a point source, is determined by a device which comprises a gas filled enclosure having a flat radiation entrance window. Flat electrodes establish an electrical field of such amplitude that there occurs conversion of said radiation into photo electrons and avalanche electron multiplication resulting in delivery of a burst or pulse of electrons per conversion whose height is an increasing function of the travel path of the electrons avalanche from the location of the conversion event to the planar outlet electrode. A detector located in a second portion of the enclosure receives the pulse of electrons and determines the coordinates and the pulse height of the pulse.

Growing community of inventors

Paris, France

Georges Charpak