EP0099285A1 - Scintillative rays conversion screen and process for the manufacture of the same - Google Patents

Scintillative rays conversion screen and process for the manufacture of the same Download PDF

Info

Publication number
EP0099285A1
EP0099285A1 EP83401370A EP83401370A EP0099285A1 EP 0099285 A1 EP0099285 A1 EP 0099285A1 EP 83401370 A EP83401370 A EP 83401370A EP 83401370 A EP83401370 A EP 83401370A EP 0099285 A1 EP0099285 A1 EP 0099285A1
Authority
EP
European Patent Office
Prior art keywords
screen
layer
scintillator
photocathode
screen according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP83401370A
Other languages
German (de)
French (fr)
Other versions
EP0099285B1 (en
Inventor
Dominique Delattre
Henri Rougeot
Catherine Tassin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thales SA
Original Assignee
Thomson CSF SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0099285A1 publication Critical patent/EP0099285A1/en
Application granted granted Critical
Publication of EP0099285B1 publication Critical patent/EP0099285B1/en
Expired legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K4/00—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/36—Photoelectric screens; Charge-storage screens
    • H01J29/38—Photoelectric screens; Charge-storage screens not using charge storage, e.g. photo-emissive screen, extended cathode
    • H01J29/385—Photocathodes comprising a layer which modified the wave length of impinging radiation

Definitions

  • the present invention relates to a scintillator radiation converter screen. It also relates to a method of manufacturing such a screen.
  • Radiation converting scintillator screens are well known in the prior art. These screens receive X or 6 rays and convert them into light photons to which a photocathode is sensitive which covers the concave face of these screens.
  • the screen When the screen receives X-radiation, it is used in radiological image intensifier tubes or I.I.R. and when the screen receives ⁇ radiation, it is used in scintigraphy tubes.
  • scintillating radiation converting screens are generally obtained by evaporating on the concave face of a metal support, for example of aluminum, which is transparent to radiation, of cesium iodide doped with sodium or with thallium. .
  • the growth of cesium iodide takes place spontaneously in the form of juxtaposed needles which is a structure conducive to guiding the light created in cesium iodide by incident radiation.
  • the concave face of the scintillator screen thus obtained receives a photocathode sublayer which is intended to isolate the scintillator screen from the photocathode and / or to improve the surface condition of the concave face of the screen.
  • a photocathode is then deposited on this sublayer.
  • the present invention relates to a scintillator radiation converter screen which does not have the drawbacks stated above.
  • the present invention relates to a scintillator radiation converter screen which is made of a scintillator material having a needle structure and this screen has a convex face which receives the radiation and a concave face which is perfectly smooth, on which installs the photocathode.
  • the concave face of the scintillator screen according to the present invention is perfectly smooth because it is this face which is in contact with the convex face of the support during the evaporation of the scintillator material.
  • the photocathode which is deposited on this face therefore has perfectly smooth surfaces.
  • the thickness of the screen can be varied from a few tens of microns to several millimeters while retaining a perfectly smooth concave face.
  • the scintillator screen when it is finished no longer comprises the support which was used for its manufacture.
  • FIG. 1 represents the diagram seen in section, of a scintillator screen according to the prior art.
  • This screen is obtained by evaporating cesium iodide on the concave face of a thin metal support 1, made of aluminum for example, which is transparent to X or Y radiation to be analyzed.
  • the growth of cesium iodide takes place in the form of needles 2 terminated by tetrahedral crystals which are represented in a box which shows in more detail the structure of the screen.
  • the concave face of the scintillator screen thus obtained is very irregular.
  • a photocathode 3 sublayer is deposited to chemically isolate the scintillator screen 2 from the photocathode and / or to improve the surface condition of the concave face of the screen.
  • a photocathode 4 is then deposited on the sublayer 3.
  • FIG. 2 represents the diagram, seen in section, of an embodiment of a screen according to the invention.
  • this screen consists of a scintillator material 2 having a structure in needles.
  • the box on the right shows that the concave face of this screen is perfectly smooth. It is on this face that the photocathode 4 is deposited, with, optionally, between this concave face and the photocathode, a sublayer 3 of photocathode, made of phosphovanadates for example.
  • This support can have any thickness. It can be made of any material, glass or metal, which has a coefficient of thermal expansion different from that of the scintillator material used.
  • the scintillator screen is obtained by evaporation of the scintillator material on the convex face of the support. After evaporation, the screen is separated from the support by simple heating thanks to the smooth surface of the convex face of the support and thanks to the difference between the coefficients of thermal expansion of the support and of the scintillator material.
  • the concave face is perfectly smooth because it is this face which was in contact with the convex face of the support during the evaporation of the scintillator material.
  • the concave face of the screen has an optical polish. The diameter of the grains on this face varies from 0.1 to 50 micrometers approximately.
  • the thickness of the screen can vary, depending on the use, between a few tens of microns and a few millimeters while retaining a perfectly smooth concave face.
  • the scintillator screen has a structure of finely divided needles. It can then be used in high definition radiological image intensifier tubes.
  • the evaporation support is heated during evaporation, at temperatures ranging from 100 to 600 ° C. for example, a structure in agglomerated needles is obtained which is more monolithic which allows this screen to be used in scintigraphy.
  • the evaporation support can be made of aluminum for example.
  • the scintillator material used can be an alkali halide, such as cesium iodide doped with sodium or thallium, or such as potassium iodide doped with thallium. It is also possible to use as scintillating material tungstates, sulphides or metallic sulphates for example.
  • a layer 5 can be placed on the convex face of the screen ensuring its rigidity.
  • This layer ensuring the rigidity of the screen can consist, for example, of a glass or of an enamel with a low melting point, or of any organic substance supporting the tube firing temperatures such as for example epoxy resin, parylene, polyimides, or cryolite, for example.
  • the convex face of the screen can also be provided with a layer reflecting the light produced in the screen by the incident radiation. This layer returns to the photocathode all the light arriving on the convex face of the screen.
  • This layer can consist, for example, of any evaporated metal such as aluminum or nichrome.
  • This layer consists of a high density material with a high atomic number, deposited in a thin layer, such as barium oxide, lead or tungsten. This type of material promotes the photoelectric emission and the stopping power with respect to ionizing radiation.
  • a layer of indium or tin can serve both to reflect the light produced in the screen by the incident radiation and also to ensure the rigidity of the screen.
  • a layer can be obtained by sputtering, by evaporation, by projection or by any other known method.
  • the photocathodes which are deposited there have a minimum surface electrical resistance which no longer depends so much on the scintillator screen but especially on the photocathode which is deposited there.
  • a photocathode 4 is deposited, consisting for example of cesium and antimony.
  • a support grid 7 having the same concavity as the screen, as shown in Figure 3.
  • This grid must be transparent to the flow of incident radiation. It can be nickel or iron, for example.
  • the screen shown comprises a layer 6 increasing the efficiency of quantum detection of the screen, a layer 2 of needle scintillator material whose concave face is perfectly polished, a photocathode sublayer 3 and a photocathode 4.
  • a metal ring 8 is evaporated on the concave face of the screen at the periphery of this face.
  • Pressure tabs 9 are applied to this ring and serve as connections with the photocathode.
  • the screen according to the invention when it is sufficiently thick can also be mounted in a tube without the use of a support grid.
  • Various embodiments of the screen according to the invention are obtained by providing one or both sides, or both sides of this screen, with one or more of the various layers mentioned above which can be superimposed in an indifferent order.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Conversion Of X-Rays Into Visible Images (AREA)
  • Measurement Of Radiation (AREA)

Abstract

1. Method of fabricating a scintillation material layer for a radiation conversion scintillation screen, receiving the X or gamma rays and converting them into light photons, this scintillation material layer (2) being obtained by evaporation on a carrier formed of a material having a thermal expansion coefficient different from that of the scintillation material (2), characterized in that the evaporation is performed on the perfectly smooth convex face of the carrier and in that, after evaporation, the scintillation material layer (2) is separated from the carrier simply by heating.

Description

La présente invention concerne un écran scintillateur convertisseur de rayonnement. Elle concerne également un procédé de fabrication d'un tel écran.The present invention relates to a scintillator radiation converter screen. It also relates to a method of manufacturing such a screen.

Les écrans scintillateurs convertisseurs de rayonnement sont bien connus dans l'art antérieur. Ces écrans reçoivent des rayons X ou 6 et les convertissent en photons lumineux auxquels est sensible une photocathode qui recouvre la face concave de ces écrans.Radiation converting scintillator screens are well known in the prior art. These screens receive X or 6 rays and convert them into light photons to which a photocathode is sensitive which covers the concave face of these screens.

Lorsque l'écran reçoit un rayonnement X, il est utilisé dans des tubes intensificateurs d'images radiologiques ou I.I.R. et lorsque l'écran reçoit un rayonnement γ, il est utilisé dans des tubes de scintigraphie.When the screen receives X-radiation, it is used in radiological image intensifier tubes or I.I.R. and when the screen receives γ radiation, it is used in scintigraphy tubes.

Dans l'art antérieur, les écrans scintillateurs convertisseurs de rayonnement sont généralement obtenus en évaporant sur la face concave d'un support métallique, en aluminium par exemple, qui est transparent au rayonnement, de J'iodure de césium dopé au sodium ou au thallium. La croissance de l'iodure de césium s'effectue spontanément sous forme d'aiguilles juxtaposées ce qui est une structure propice au guidage de la lumière créée dans l'iodure de césium par Je rayonnement incident. La face concave de l'écran scintilIateur ainsi obtenu reçoit une sous-couche de photocathode qui est destinée à isoler l'écran scintillateur de la photocathode et/ou à améliorer l'état de surface de la face concave de l'écran.In the prior art, scintillating radiation converting screens are generally obtained by evaporating on the concave face of a metal support, for example of aluminum, which is transparent to radiation, of cesium iodide doped with sodium or with thallium. . The growth of cesium iodide takes place spontaneously in the form of juxtaposed needles which is a structure conducive to guiding the light created in cesium iodide by incident radiation. The concave face of the scintillator screen thus obtained receives a photocathode sublayer which is intended to isolate the scintillator screen from the photocathode and / or to improve the surface condition of the concave face of the screen.

Une photocathode est ensuite déposée sur cette sous-couche.A photocathode is then deposited on this sublayer.

Les écrans scintillateurs connus dans l'art antérieur présentent un certain nombre d'inconvénients parmi lesquels on peut citer :

  • - le fait que la face concave de l'écran scintillateur obtenu ne soit pas parfaitement lisse à cause de la structure en aiguilles du matériau scintillateur. Il est difficile de colmater parfaitement les irrégularités de cette face, même en utilisant une sous-couche de photocathode. La photocathode qui est déposée présente une résistance' électrique superficielle élevée. Au-delà d'un certain flux de rayonnement incident, des variations locales importantes du potentiel à la surface de la photocathode apparaissent ce qui entraîne une défocalisation de l'image électronique. De plus, les irrégularités de surface de la photocathode nuisent à sa sensibilité. La présence de nombreuses crevasses emprisonnant des poches de gaz à proximité de la couche photosensible est à l'origine d'un rendement de photo- émission réduit ;
  • - le fait qu'on soit tenu à limiter l'épaisseur de l'écran car le nombre de fissures et de discontinuités superficielles augmente avec cette épaisseur. Cet inconvénient est particulièrement gênant dans le cas des écrans destinés à la gammagraphie où des écrans scintillateurs épais sont requis ;
  • - la présence dans l'écran scintillateur terminé du support sur lequel le matériau scintillateur a été évaporé. Ce support est largement transparent au rayonnement incident mais arrête malgré tout une fraction de ce rayonnement.
The scintillator screens known in the prior art have a certain number of drawbacks, among which we can cite:
  • - the fact that the concave face of the scintillator screen obtained is not perfectly smooth because of the needle structure of the scintillator material. It is difficult to perfectly seal irregularities on this face, even when using a photocathode undercoat. The photocathode which is deposited has a resis high surface electric tance. Beyond a certain incident radiation flux, significant local variations in the potential at the surface of the photocathode appear, which results in defocusing of the electronic image. In addition, surface irregularities of the photocathode affect its sensitivity. The presence of numerous crevices trapping pockets of gas near the photosensitive layer is at the origin of a reduced photo-emission efficiency;
  • - the fact that we are required to limit the thickness of the screen because the number of cracks and surface discontinuities increases with this thickness. This drawback is particularly troublesome in the case of screens intended for radiography where thick scintillating screens are required;
  • - the presence in the finished scintillator screen of the support on which the scintillator material has been evaporated. This support is largely transparent to incident radiation but still stops a fraction of this radiation.

La présente invention concerne un écran scintillateur convertisseur de rayonnement qui ne présente pas les inconvénients énoncés ci-dessus.The present invention relates to a scintillator radiation converter screen which does not have the drawbacks stated above.

Selon la revendication 1, la présente invention concerne un écran scintillateur convertisseur de rayonnement qui est constitué d'un matériau scintillateur présentant une structure en aiguilles et cet écran présente une face convexe qui reçoit le rayonnement et une face concave qui est parfaitement lisse, sur laquelle repose la photocathode.According to claim 1, the present invention relates to a scintillator radiation converter screen which is made of a scintillator material having a needle structure and this screen has a convex face which receives the radiation and a concave face which is perfectly smooth, on which installs the photocathode.

Selon la revendication 12, la présente invention concerne également un procédé de fabrication d'un tel écran qui comporte les étapes suivantes ;

  • - l'écran scintillateur est obtenu par évaporation sur un support présentant une face convexe parfaitement lisse et constitué d'un matériau présentant un coefficient de dilatation thermique différent de celui du matériau scintillateur ;
  • - après évaporation, l'écran scintillateur est séparé du support par simple chauffage.
According to claim 12, the present invention also relates to a method of manufacturing such a screen which comprises the following steps;
  • - The scintillator screen is obtained by evaporation on a support having a perfectly smooth convex face and made of a material having a coefficient of thermal expansion different from that of the scintillator material;
  • - after evaporation, the scintillator screen is separated from the support by simple heating.

La face concave de l'écran scintillateur selon la présente invention est parfaitement lisse car c'est cette face qui se trouve en contact avec la face convexe du support pendant l'évaporation du matériau scintillateur. La photocathode qui est déposée sur cette face a donc des surfaces parfaitement lisses. On peut faire varier l'épaisseur de l'écran de quelques dizaines de microns à plusieurs millimètres tout en conservant une face concave parfaitement lisse. Enfin, selon la présente invention, l'écran scintillateur lorsqu'il est terminé ne comporte plus le support ayant servi à sa fabrication.The concave face of the scintillator screen according to the present invention is perfectly smooth because it is this face which is in contact with the convex face of the support during the evaporation of the scintillator material. The photocathode which is deposited on this face therefore has perfectly smooth surfaces. The thickness of the screen can be varied from a few tens of microns to several millimeters while retaining a perfectly smooth concave face. Finally, according to the present invention, the scintillator screen when it is finished no longer comprises the support which was used for its manufacture.

D'autres objets, caractéristiques et résultats de l'invention ressortiront de la description suivante, donnée à titre d'exemple non limitatif et illustrée par-les figures annexées qui représentent :

  • - la figure 1, le schéma d'un écran scintillateur selon l'art antérieur ;
  • - les figures 2 et 3, deux modes de réalisation d'un écran scintillateur selon l'invention.
Other objects, characteristics and results of the invention will emerge from the following description, given by way of nonlimiting example and illustrated by the appended figures which represent:
  • - Figure 1, the diagram of a scintillator screen according to the prior art;
  • - Figures 2 and 3, two embodiments of a scintillator screen according to the invention.

Sur les différentes figures, les mêmes repères désignent les mêmes éléments, mais pour des raisons de clarté, les cotes et proportions des divers éléments ne sont pas respectées.In the different figures, the same references designate the same elements, but for reasons of clarity, the dimensions and proportions of the various elements are not observed.

La figure 1 représente le schéma vu en coupe, d'un écran scintillateur selon l'art antérieur.FIG. 1 represents the diagram seen in section, of a scintillator screen according to the prior art.

Cet écran est obtenu en évaporant de l'iodure de césium sur la face concave d'un support métallique mince 1, en aluminium par exemple, qui est transparent au rayonnement X ou Y à analyser. La croissance de l'iodure de césium s'effectue sous forme d'aiguilles 2 terminées par des cristaux tétraédriques qui sont représentées dans un encadré qui montre plus en détails la structure de l'écran. On constate dans l'encadré de la figure 1 que la face concave de l'écran scintillateur ainsi obtenue est très irrégulière. Sur cette face concave, on dépose une sous-couche de photocathode 3 pour isoler au point de vue chimique l'écran scintillateur 2 de la photocathode et/ou pour améliorer l'état de surface de la face concave de l'écran. Une photocathode 4 est ensuite déposée sur la sous-couche 3.This screen is obtained by evaporating cesium iodide on the concave face of a thin metal support 1, made of aluminum for example, which is transparent to X or Y radiation to be analyzed. The growth of cesium iodide takes place in the form of needles 2 terminated by tetrahedral crystals which are represented in a box which shows in more detail the structure of the screen. We see in the box of Figure 1 that the concave face of the scintillator screen thus obtained is very irregular. On this concave face, a photocathode 3 sublayer is deposited to chemically isolate the scintillator screen 2 from the photocathode and / or to improve the surface condition of the concave face of the screen. A photocathode 4 is then deposited on the sublayer 3.

La figure 2 représente le schéma, vu en coupe, d'un mode de réalisation d'un écran selon l'invention.FIG. 2 represents the diagram, seen in section, of an embodiment of a screen according to the invention.

Sur les deux encadrés qui montrent de façon plus détaillée la structure de l'écran, selon l'invention, on constate que cet écran est constitué d'un matériau scintillateur 2 présentant une structure en aiguilles. L'encadré de droite montre que la face concave de cet écran est parfaitement lisse. C'est sur cette face qu'est déposée la photocathode 4, avec, éventuellement, entre cette face concave et la photocathode, une sous-couche 3 de photocathode, en phospho- vanadates par exemple.On the two boxes which show in more detail the structure of the screen according to the invention, it can be seen that this screen consists of a scintillator material 2 having a structure in needles. The box on the right shows that the concave face of this screen is perfectly smooth. It is on this face that the photocathode 4 is deposited, with, optionally, between this concave face and the photocathode, a sublayer 3 of photocathode, made of phosphovanadates for example.

Pour obtenir l'écran selon l'invention, on peut utiliser le procédé exposé ci-après.To obtain the screen according to the invention, the method described below can be used.

II faut disposer d'un support présentant une face convexe parfaitement polie. Ce support peut avoir une épaisseur quelconque. Il peut être constitué d'un matériau quelconque, verre ou métal, qui présente un coefficient de dilatation thermique différent de celui du matériau scintillateur utilisé.It is necessary to have a support having a perfectly polished convex face. This support can have any thickness. It can be made of any material, glass or metal, which has a coefficient of thermal expansion different from that of the scintillator material used.

L'écran scintillateur est obtenu par évaporation du matériau scintillateur sur la face convexe du support. Après évaporation, l'écran est séparé du support par simple chauffage grâce à la surface lisse de la face convexe du support et grâce à la différence entre les coefficients de dilatation thermique du support et du matériau scintillateur.The scintillator screen is obtained by evaporation of the scintillator material on the convex face of the support. After evaporation, the screen is separated from the support by simple heating thanks to the smooth surface of the convex face of the support and thanks to the difference between the coefficients of thermal expansion of the support and of the scintillator material.

On obtient ainsi un écran scintillateur tel que celui représenté sur la figure 2 dont la face concave est parfaitement lisse car c'est cette face qui était en contact avec la face convexe du support pendant l'évaporation du matériau scintillateur. La face concave de l'écran présente un poli optique. Le diamètre des grains sur cette face varie de 0,1 à 50 micro-métres environ.This gives a scintillator screen such as that shown in Figure 2, the concave face is perfectly smooth because it is this face which was in contact with the convex face of the support during the evaporation of the scintillator material. The concave face of the screen has an optical polish. The diameter of the grains on this face varies from 0.1 to 50 micrometers approximately.

Comme on peut le voir sur l'encadré de gauche de la figure 2, " c'est la face convexe de l'écran qui présente une surface assez irrégulière à cause des extrémités des aiguilles du matériau scintillateur mais cela n'a pas d'importance car il n'y a pasde conduction sur cette face.As we can see on the left sidebar of figure 2, " it is the convex face of the screen which presents a rather irregular surface because of the ends of the needles of the scintillator material but this has no importance because there is no conduction on this face.

Ln effet, la conduction est assurée par la photocathode qui est déposée sur la face concave tout à fait lisse. On ne risque donc pas de voir comme dans l'art antérieur, des cratères de micro-structures interrompre la continuité de la couche en contact avec la photocathode et donc la conduction.Ln effect, the conduction is ensured by the photocathode which is deposited on the concave face quite smooth. There is therefore no risk of seeing, as in the prior art, craters of micro-structures interrupt the continuity of the layer in contact with the photocathode and therefore the conduction.

L'épaisseur de l'écran peut varier, selon l'utilisation, entre quelques dizaines de microns et quelques millimètres tout en conservant une face concave parfaitement lisse.The thickness of the screen can vary, depending on the use, between a few tens of microns and a few millimeters while retaining a perfectly smooth concave face.

Si le support d'évaporation est maintenu froid pendant J'évaporation, l'écran scintillateur présente une structure en aiguilles finement divisées. Il peut alors être utilisé dans les tubes intensificateurs d'images radiologiques de haute définition.If the evaporation support is kept cold during evaporation, the scintillator screen has a structure of finely divided needles. It can then be used in high definition radiological image intensifier tubes.

Si par contre le support d'évaporation est chauffé pendant l'évaporation, à des températures allant de 100 à 600°C par exemple, on obtient une structure en aiguilles agglomérées plus monolithique qui permet d'utiliser cet écran en scintigraphie.If, on the other hand, the evaporation support is heated during evaporation, at temperatures ranging from 100 to 600 ° C. for example, a structure in agglomerated needles is obtained which is more monolithic which allows this screen to be used in scintigraphy.

Le support d'évaporation peut être réalisé en aluminium par exemple. Le matériau scintillateur utilisé peut être un halogénure alcalin, tel que l'iodure de césium dopé au sodium ou au thallium, ou tel que l'iodure de potassium dopé au thallium. On peut aussi utiliser comme matériau scintillateur des tungstates, des sulfures ou des sulfates métalliques par exemple.The evaporation support can be made of aluminum for example. The scintillator material used can be an alkali halide, such as cesium iodide doped with sodium or thallium, or such as potassium iodide doped with thallium. It is also possible to use as scintillating material tungstates, sulphides or metallic sulphates for example.

On constate qu'en utilisant le procédé précédemment décrit on obtient un écran scintillateur dont les deux faces sont accessibles pour tout traitement ultérieur souhaité car le support d'évaporation ne fait pas partie de l'écran terminé au contraire de ce qui se passe dans les écrans selon l'art antérieur.It can be seen that by using the method described above, a scintillator screen is obtained, the two faces of which are accessible for any subsequent treatment desired since the evaporation support is not part of the finished screen, unlike what happens in the screens according to the prior art.

Pour accroître la tenue mécanique de l'écran, et particulièrement dans le cas d'un écran de faible épaisseur en structure d'aiguilles finement divisées, on peut disposer sur la face convexe de l'écran une couche 5 assurant sa rigidité. une telle couche est représentée sur la figure 2. Cette couche assurant la rigidité de l'écran peut être constituée par exemple d'un verre ou d'un émail à bas point de fusion, ou de toute substance organique supportant les températures d'ctuvage du tube telles que par exemple la résine époxy, le parylène, les polyimides, ou la cryolite, par exemple.To increase the mechanical strength of the screen, and particularly in the case of a thin screen in the structure of finely divided needles, a layer 5 can be placed on the convex face of the screen ensuring its rigidity. such a layer is shown in FIG. 2. This layer ensuring the rigidity of the screen can consist, for example, of a glass or of an enamel with a low melting point, or of any organic substance supporting the tube firing temperatures such as for example epoxy resin, parylene, polyimides, or cryolite, for example.

La face convexe de l'écran peut être aussi munie d'une couche réfléchissant la lumière produite dans l'écran par le rayonnement incident. Cette couche renvoie vers la photocathode toute la lumière arrivant sur la face convexe de l'écran. Cette couche peut être constituée, par exemple, d'un métal évaporé quelconque tel que l'aluminium ou le nichrome.The convex face of the screen can also be provided with a layer reflecting the light produced in the screen by the incident radiation. This layer returns to the photocathode all the light arriving on the convex face of the screen. This layer can consist, for example, of any evaporated metal such as aluminum or nichrome.

On peut aussi munir la face convexe de l'écran d'une couche accroissant l'efficacité de détection quantique de l'écran. Cette couche est constituée d'un matériau de haute densité à numéro atomique élevé, déposé en couche mince, tel que J'oxyde de baryum, de plomb ou de tungstène. Ce type de matériau favorise l'émission photoélectrique et Je pouvoir d'arrêt vis-à-vis du rayonnement ionisant.It is also possible to provide the convex face of the screen with a layer increasing the efficiency of quantum detection of the screen. This layer consists of a high density material with a high atomic number, deposited in a thin layer, such as barium oxide, lead or tungsten. This type of material promotes the photoelectric emission and the stopping power with respect to ionizing radiation.

Il est donc possible de disposer sur la face convexe de l'écran une, deux ou trois couches successives remplissant chacune J'une des fonctions suivantes : couche assurant la rigidité de l'écran, couche réfléchissant la lumière produite dans l'écran par le rayonnement incident, couche accroissant l'efficacité de détection quantique de l'écran. L'ordre des diverses couches peut varier.It is therefore possible to have on the convex face of the screen one, two or three successive layers each fulfilling one of the following functions: layer ensuring the rigidity of the screen, layer reflecting the light produced in the screen by the incident radiation, layer increasing the quantum detection efficiency of the screen. The order of the various layers may vary.

Il est possible d'utiliser des couches de matériaux remplissant deux des fonctions énoncées. Par exemple, une couche d'indium ou d'étain peut servir à la fois à réfléchir la lumière produite dans l'écran par le rayonnement incident et assurer aussi la rigidité de l'écran. Une telle couche peut être obtenue par pulvérisation cathodique, par évaporation, par projection ou par toute autre méthode connue.It is possible to use layers of materials fulfilling two of the stated functions. For example, a layer of indium or tin can serve both to reflect the light produced in the screen by the incident radiation and also to ensure the rigidity of the screen. Such a layer can be obtained by sputtering, by evaporation, by projection or by any other known method.

En ce qui concerne la face concave de l'écran, cette face étant parfaitement polie, les photocathodes qui y sont déposées ont une résistance éléctrique superficielle minimale qui ne dépend plus tellement de l'écran scintillateur mais surtout de la photocathode qui y est déposée.As regards the concave face of the screen, this face being perfectly polished, the photocathodes which are deposited there have a minimum surface electrical resistance which no longer depends so much on the scintillator screen but especially on the photocathode which is deposited there.

La face concave de l'écran est généralement- recouverte d'au moins une ................................... coucha assurant au moins l'une des fonctions suivantes :

  • - couche réduisant encore la résistance électrique superficielle de la photocathode, couche assurant la compatibilité du point de vue chimique entre l'écran scintillateur et la photocathode. On peut déposer sur la face concave de l'écran une sous-couche 3 qui est représentée sur la figure 2. Cette sous-couche peut être constituée d'oxyde d'indium ou d'un métal en couche mince, tel que l'aluminium, qui est largement transparent à la lumière produite par le scintillateur.
The concave face of the screen is generally covered with at least one .................................. . coucha performing at least one of the following functions:
  • - layer further reducing the surface electrical resistance of the photocathode, layer ensuring compatibility from the chemical point of view between the scintillator screen and the photocathode. One can deposit on the concave face of the screen a sublayer 3 which is represented in FIG. 2. This sublayer can consist of indium oxide or of a metal in a thin layer, such as aluminum, which is largely transparent to the light produced by the scintillator.

Sur la sous-couche, on dépose une photocathode 4, constituée par exemple de césium et d'antimoine.On the sub-layer, a photocathode 4 is deposited, consisting for example of cesium and antimony.

Pour monter l'écran selon l'invention dans le tube où il va être utilisé, on peut employer une grille support 7 ayant même concavité que l'écran, comme cela est représenté sur la figure 3. Cette grille doit être transparente au flux de rayonnement incident. Elle peut être en nickel ou en fer, par exemple.To mount the screen according to the invention in the tube where it will be used, one can use a support grid 7 having the same concavity as the screen, as shown in Figure 3. This grid must be transparent to the flow of incident radiation. It can be nickel or iron, for example.

Sur la figure 3, l'écran représenté, comporte une couche 6 accroissant l'efficacité de détection quantique de l'écran, une couche 2 de matériau scintillateur en aiguilles dont la face concave est parfaitement polie, une sous-couche de photocathode 3 et une photocathode 4.In FIG. 3, the screen shown comprises a layer 6 increasing the efficiency of quantum detection of the screen, a layer 2 of needle scintillator material whose concave face is perfectly polished, a photocathode sublayer 3 and a photocathode 4.

On voit sur la figure 3, qu'un anneau métallique 8 est évaporé sur la face concave de l'écran à la périphérie de cette face. Des languettes de pression 9 sont appliquées sur cet anneau et servent de connexions avec la photocathode.We see in Figure 3, a metal ring 8 is evaporated on the concave face of the screen at the periphery of this face. Pressure tabs 9 are applied to this ring and serve as connections with the photocathode.

L'écran selon l'invention lorsqu'il est suffisamment épais peut aussi être monté dans un tube sans l'utilisation d'une grille-support.The screen according to the invention when it is sufficiently thick can also be mounted in a tube without the use of a support grid.

On obtient divers modes de réalisation de l'écran selon l'invention en munissant l'une des deux faces, ou les deux faces de cet écran, d'une ou plusieurs des diverses couches dont il a été question précédemment qui peuvent être superposées dans un ordre indifférent.Various embodiments of the screen according to the invention are obtained by providing one or both sides, or both sides of this screen, with one or more of the various layers mentioned above which can be superimposed in an indifferent order.

Claims (14)

1. Ecran scintillateur convertisseur de rayonnement, qui reçoit des rayons X ou γ et les convertit en photons lumineux auxquels est sensible une photocathode (4) qui recouvre l'une des faces de cet écran, caractérisé en ce que cet écran est constitué d'un matériau scintillateur (2) présentant une structure en aiguilles et en ce qu'il présente une face convexe qui reçoit le rayonnement et une face concave qui est parfaitement lisse, sur laquelle repose la photocathode (4).1. Scintillator screen converter of radiation, which receives X or γ rays and converts them into light photons to which is sensitive a photocathode (4) which covers one of the faces of this screen, characterized in that this screen consists of a scintillator material (2) having a needle structure and in that it has a convex face which receives the radiation and a concave face which is perfectly smooth, on which the photocathode (4) rests. 2. Ecran selon la revendication 1, caractérisé en ce que la face convexe de l'écran est recouverte d'au moins une couche assurant au moins l'une des fonctions suivantes : couche assurant la rigidité de récran (5), couche réfléchissant la lumière produite dans l'écran par le rayonnement incident, couche accroissant l'efficacité de détection quantique de l'écran (6).2. Screen according to claim 1, characterized in that the convex face of the screen is covered with at least one layer ensuring at least one of the following functions: layer ensuring the rigidity of the screen (5), layer reflecting the light produced in the screen by the incident radiation, layer increasing the efficiency of quantum detection of the screen (6). 3. Ecran selon l'une des revendications 1 ou 2, caractérisé en ce que la face concave de l'écran est recouverte d'au moins une couche (6) assurant au moins l'une des fonctions suivantes : couche assurant la compatibilité avec la photocathode, couche assurant la réduction de la résistance superficielle de la photocathode.3. Screen according to one of claims 1 or 2, characterized in that the concave face of the screen is covered with at least one layer (6) ensuring at least one of the following functions: layer ensuring compatibility with the photocathode, a layer ensuring the reduction of the surface resistance of the photocathode. 4. Ecran selon l'une des revendications 1 à 3, caractérisé en ce que le matériau scintillateur (2) utilisé est un halogénure alcalin, tel que l'iodure de césium dopé au sodium ou au thallium ou tel que l'iodure de potassium dopé au thallium.4. Screen according to one of claims 1 to 3, characterized in that the scintillator material (2) used is an alkali halide, such as cesium iodide doped with sodium or thallium or such as potassium iodide doped with thallium. 5. Ecran selon l'une des revendications 1 à 4, caractérisé en ce que le matériau scintillateur (2) présente une structure en aiguilles finement divisées ou une structure en aiguilles agglomérées.5. Screen according to one of claims 1 to 4, characterized in that the scintillator material (2) has a structure of finely divided needles or a structure of agglomerated needles. 6. Ecran selon l'une des revendications 1 à 5, caractérisé en ce que le matériau scintillateur a une épaisseur allant de quelques dizaines de microns à quelques millimètres.6. Screen according to one of claims 1 to 5, characterized in that the scintillator material has a thickness ranging from a few tens of microns to a few millimeters. 7. Ecran selon l'une des revendications 1 à 6, caractérisé en ce que la face concave parfaitement lisse comporte des grains dont le diamètre varie de 0,1 à 50 pm.7. Screen according to one of claims 1 to 6, characterized in that the perfectly smooth concave face comprises grains whose diameter varies from 0.1 to 50 μm. 8. Ecran selon l'une des revendications 1 à 7, caractérisé en ce que la couche assurant 1a rigidité de l'écran (5) est constituée d'un verre ou d'un émail à bas point de fusion, ou d'une substance organique telle que la résine époxy, le parylène, les polyimides, la cryolite.8. Screen according to one of claims 1 to 7, characterized in that the layer ensuring the rigidity of the screen (5) consists of a glass or an enamel with a low melting point, or a organic substance such as epoxy resin, parylene, polyimides, cryolite. 9. Ecran selon l'une des revendications 1 à 8, caractérisé en ce que la couche réfléchissant la lumière produite dans J'écran par le rayonnement incident est en aluminium ou en nichrome.9. Screen according to one of claims 1 to 8, characterized in that the layer reflecting the light produced in the screen by the incident radiation is aluminum or nichrome. 10. Ecran selon l'une des revendications 1 à 9, caractérisé en ce que la couche (6) accroissant l'efficacité de détection quantique est constituée par un matériau de haute densité, déposé en couche mince, tel que l'oxyde de baryum, de plomb ou de tungstène.10. Screen according to one of claims 1 to 9, characterized in that the layer (6) increasing the quantum detection efficiency consists of a high density material, deposited in a thin layer, such as barium oxide , lead or tungsten. 11. Ecran selon l'une des revendications 1 à 10, caractérisé en ce que la couche assurant la réduction de la résistance superficielle de la photocathode est constitué d'oxyde d'indium ou est une mince couche métallique.11. Screen according to one of claims 1 to 10, characterized in that the layer ensuring the reduction of the surface resistance of the photocathode consists of indium oxide or is a thin metallic layer. 12. Procédé de fabrication d'un écran selon la revendication 1, caractérisé en ce qu'il comporte les étapes suivantes : - l'écran scintillateur (2) est obtenu par évaporation sur un support présentant une face convexe parfaitement lisse et constitué d'un matériau présentant un coefficient de dilatation thermique différent de celui du matériau scintillateur (2) ; - après évaporation, l'écran scintillateur (2) est séparé du support par simple chauffage. 12. A method of manufacturing a screen according to claim 1, characterized in that it comprises the following steps: - The scintillator screen (2) is obtained by evaporation on a support having a perfectly smooth convex face and made of a material having a coefficient of thermal expansion different from that of the scintillator material (2); - after evaporation, the scintillator screen (2) is separated from the support by simple heating. 13. Procédé selon la revendication 12, caractérisé en ce que le support est maintenu froid pendant l'évaporation, une structure en aiguille finement divisées étant obtenue.13. The method of claim 12, characterized in that the support is kept cold during evaporation, a finely divided needle structure being obtained. 14. Procédé selon la revendication 12, caractérisé en ce que le substrat est chauffé pendant J'évaporation, une structure en aiguilles agglomérées étant obtenue.14. The method of claim 12, characterized in that the substrate is heated during evaporation, a structure of agglomerated needles being obtained.
EP83401370A 1982-07-13 1983-07-04 Scintillative rays conversion screen and process for the manufacture of the same Expired EP0099285B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8212285 1982-07-13
FR8212285A FR2530367A1 (en) 1982-07-13 1982-07-13 SCINTILLATOR SCREEN RADIATION CONVERTER AND METHOD FOR MANUFACTURING SUCH SCREEN

Publications (2)

Publication Number Publication Date
EP0099285A1 true EP0099285A1 (en) 1984-01-25
EP0099285B1 EP0099285B1 (en) 1987-01-21

Family

ID=9275953

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83401370A Expired EP0099285B1 (en) 1982-07-13 1983-07-04 Scintillative rays conversion screen and process for the manufacture of the same

Country Status (4)

Country Link
EP (1) EP0099285B1 (en)
JP (1) JPS5924300A (en)
DE (1) DE3369420D1 (en)
FR (1) FR2530367A1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0185534A2 (en) * 1984-12-17 1986-06-25 Konica Corporation Radiation image storage panel
EP0197597A1 (en) * 1985-04-03 1986-10-15 Koninklijke Philips Electronics N.V. X-ray image intensifier tube including a luminescent layer which absorbs secondary radiation
EP0219153A1 (en) * 1985-09-20 1987-04-22 Koninklijke Philips Electronics N.V. X-ray image intensifier tube having an optimized microstructure
US4764946A (en) * 1984-11-05 1988-08-16 Innofinance Altalanos Innovacios Penzwtezet Method and modifying body for influencing the effect of X-ray or gamma radiation on a target sensitive to the radiation

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63262600A (en) * 1987-04-20 1988-10-28 富士写真フイルム株式会社 Radiation picture conversion panel and manufacture thereof
JP2815881B2 (en) * 1988-03-04 1998-10-27 株式会社東芝 Method of manufacturing X-ray image tube
AU4168699A (en) 1998-06-18 2000-01-05 Hamamatsu Photonics K.K. Method of organic film deposition
CN1304853C (en) * 2000-09-11 2007-03-14 浜松光子学株式会社 Scintillator panel, radiation image sensor and method for producing them
JP4593806B2 (en) * 2001-02-09 2010-12-08 キヤノン株式会社 Manufacturing method of radiation detection apparatus, manufacturing method of fluorescent plate, and manufacturing apparatus of radiation detection apparatus
JP4208687B2 (en) * 2003-09-29 2009-01-14 株式会社東芝 Image sensor
JP2011247686A (en) * 2010-05-25 2011-12-08 Fujifilm Corp Imaging apparatus for radiation image
JP2015200528A (en) * 2014-04-04 2015-11-12 キヤノン株式会社 Radiation imaging apparatus, method of manufacturing the same and radiation imaging system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3030313A (en) * 1958-06-19 1962-04-17 Du Pont Process for making thallium activated potassium iodide phosphor
US3795531A (en) * 1970-02-03 1974-04-05 Varian Associates X-ray image intensifier tube and method of making same
EP0042149A1 (en) * 1980-06-16 1981-12-23 Kabushiki Kaisha Toshiba Radiation excited phosphor screen and method for manufacturing the same

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE786084A (en) * 1971-07-10 1973-01-10 Philips Nv LUMINESCENT SCREEN WITH MOSAIC STRUCTURE
US3852131A (en) * 1972-05-17 1974-12-03 Gen Electric Method of manufacturing x-ray image intensifier input phosphor screen
US4184077A (en) * 1976-05-11 1980-01-15 Tokyo Shibaura Electric Co., Ltd. Input screen of an image intensifier
DE2810920A1 (en) * 1977-03-14 1978-09-21 Tokyo Shibaura Electric Co IMAGE AMPLIFIER
US4101781A (en) * 1977-06-27 1978-07-18 Hewlett-Packard Company Stable fiber optic scintillative x-ray screen and method of production
JPS5519029A (en) * 1978-07-25 1980-02-09 Ryosaku Kakimoto Production of natto (fermented soybean) frozen with liquid nitrogen in laminated carton vessel

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3030313A (en) * 1958-06-19 1962-04-17 Du Pont Process for making thallium activated potassium iodide phosphor
US3795531A (en) * 1970-02-03 1974-04-05 Varian Associates X-ray image intensifier tube and method of making same
EP0042149A1 (en) * 1980-06-16 1981-12-23 Kabushiki Kaisha Toshiba Radiation excited phosphor screen and method for manufacturing the same

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4764946A (en) * 1984-11-05 1988-08-16 Innofinance Altalanos Innovacios Penzwtezet Method and modifying body for influencing the effect of X-ray or gamma radiation on a target sensitive to the radiation
EP0185534A2 (en) * 1984-12-17 1986-06-25 Konica Corporation Radiation image storage panel
EP0185534A3 (en) * 1984-12-17 1986-11-20 Konishiroku Photo Industry Co. Ltd. Radiation image storage panel and process for making the same
EP0197597A1 (en) * 1985-04-03 1986-10-15 Koninklijke Philips Electronics N.V. X-ray image intensifier tube including a luminescent layer which absorbs secondary radiation
EP0219153A1 (en) * 1985-09-20 1987-04-22 Koninklijke Philips Electronics N.V. X-ray image intensifier tube having an optimized microstructure

Also Published As

Publication number Publication date
FR2530367B1 (en) 1985-02-22
EP0099285B1 (en) 1987-01-21
JPS5924300A (en) 1984-02-07
FR2530367A1 (en) 1984-01-20
JPH0458000B2 (en) 1992-09-16
DE3369420D1 (en) 1987-02-26

Similar Documents

Publication Publication Date Title
EP0099285B1 (en) Scintillative rays conversion screen and process for the manufacture of the same
CA2463078C (en) Solid-state x-ray detector
EP1231483B1 (en) Scintillator panel, radiation detection device, and method for manufacturing the same
FR2833358A1 (en) DIRECT Csl SCINTILLATOR COATING FOR IMPROVED LONGEVITY OF A DIGITAL X-RAY DETECTOR ASSEMBLY
EP0554145B1 (en) Image intensifier tube, particularly of the proximity focusing type
EP0559550B1 (en) Microchannel plate type intensifier tube, especially for radiological images
EP0325500B1 (en) Input screen scintillator for a radiological image intensifier tube and its manufacturing method
FR2812089A1 (en) Radiation sensor, for use in X-ray applications, includes titanium based inlet window
WO1990015432A1 (en) Input screen for radiological image intensifier tube
EP0430766A2 (en) Anode for an X-ray tube
EP1573363B1 (en) Solid-state x-ray detector
US4406973A (en) Black glass shield and method for absorbing stray light for image intensifiers
EP0013241B1 (en) Radiological intensifier tube with video output and radiological network provided with such a tube
EP0334734B1 (en) Electromagnetic image chromatic conversion device, and process for its manufacture
FR2702086A1 (en) Rotating anode for a composite X-ray tube
FR2530368A1 (en) Radiation-converting scintillating screen.
EP2099579B1 (en) Method for soldering electronic components
FR2740606A1 (en) Radiographic picture enhancer tube converting X=rays into electron beam
EP0430768A1 (en) Composite base anode for X-ray tube
EP1399943A1 (en) X-ray tube with graphite window
EP0143714B1 (en) Luminescent screen and process for manfacturing the same
FR2686732A1 (en) Graphite anode for X-ray tube and tube thus obtained
EP0013214B1 (en) Absorber of solar energy, solar collector comprising such an absorber, and solar panel provided with such collectors
EP0608168A1 (en) Image conversion tube and method of suppressing parasites in the tube
FR2467481A1 (en) Fluorescent screen for image intensifier tube - has acicular layer and covering layer to improve image quality and screen life

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): DE GB NL

17P Request for examination filed

Effective date: 19840202

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE GB NL

REF Corresponds to:

Ref document number: 3369420

Country of ref document: DE

Date of ref document: 19870226

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19960619

Year of fee payment: 14

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 19960620

Year of fee payment: 14

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19960621

Year of fee payment: 14

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19970704

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19980201

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 19970704

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee

Effective date: 19980201

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19980401