EP0317402A1 - X-ray tube having a molybdenum target - Google Patents

X-ray tube having a molybdenum target Download PDF

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Publication number
EP0317402A1
EP0317402A1 EP88402830A EP88402830A EP0317402A1 EP 0317402 A1 EP0317402 A1 EP 0317402A1 EP 88402830 A EP88402830 A EP 88402830A EP 88402830 A EP88402830 A EP 88402830A EP 0317402 A1 EP0317402 A1 EP 0317402A1
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EP
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Prior art keywords
anode
ray tube
molybdenum
target
ray
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EP88402830A
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German (de)
French (fr)
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EP0317402B1 (en
Inventor
Jacques Delair
Olivier Peyret
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General Electric CGR SA
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General Electric CGR SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H01J35/08—Anodes; Anti cathodes
    • H01J35/10—Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes

Definitions

  • the invention relates to an x-ray tube, in particular for mammography, and particularly relates to a molybdenum anode target.
  • X-radiation is obtained under the effect of an electronic bombardment of a target carried by the anode, or formed from the anode itself.
  • a small surface is subjected to electronic bombardment and constitutes the source of X-ray radiation.
  • the characteristics of X-ray radiation depend on the characteristics of the incident electron beam, and on the nature of the material of which the target is made.
  • Molybdenum targets are commonly used in X-ray tube anodes for mammography.
  • the breast has a low absorption at X, and the anomalies sought have densities very close to those of the surrounding tissues.
  • the contrast presented on an X-ray, between these anomalies and the surrounding tissues, is improved considerably when the X-ray used has a narrow band of energy containing the characteristic lines of molybdenum.
  • Molybdenum targets are commonly obtained by sintering molybdenum powder. Most often it is the anode itself which is produced, in a massive manner, by a sintering of molybdenum powder, the target being constituted by a part of the anode; the anode may be of the fixed anode type or of the rotating anode type. Other conventional methods, such as for example chemical vapor deposition, or else electrolytic deposition make it possible to deposit a layer of molybdenum on the anode in order to constitute a target on all or part of the surface of the anode, according to a focal track for example, in the case of a rotating anode.
  • this intensity is reduced by approximately 20% after three months of normal operation of the X-ray tube, and it is reduced by approximately 40% in a plane near the anode plane.
  • the present invention relates to an X-ray tube with fixed anode or rotating anode, particularly but not exclusively intended for mammography, the anode having a molybdenum target which does not exhibit the above-mentioned cracking problems or possibly after a much longer operating time and at a much lower degree than with a molybdenum target according to the prior art.
  • an X-ray tube comprising an anode and a cathode, the cathode delivering an electron beam, the anode comprising a target bombarded by the electron beam on a surface constituting the source of X-radiation, the target being made of molybdenum, is characterized in that the molybdenum is alloyed with vanadium.
  • doping molybdenum with vanadium has an important advantage in the case of an X-ray tube used in mammography, and which resides in that the lines characteristic of vanadium emitted under electron bombardment, are completely eliminated by conventional filtration of the X-rays emitted by the X-ray tube, so that the X-ray spectrum is not modified by the presence of vanadium.
  • the figure shows by way of nonlimiting example, an X-ray tube 1 according to the invention, particularly intended for application to mammography.
  • the X-ray tube 1 is conventionally contained in a sheath 2.
  • the X-ray tube 1 comprises an envelope 3 made of glass for example, containing in particular a cathode 4 and an anode 5.
  • the anode 5 is a rotating anode having the general shape of a disc, and which is carried in the center of the disc by a support shaft 7 secured to a rotor 8.
  • the rotor 8 is arranged along an axis of symmetry 9 of the anode disc 5; the rotor 8 itself being carried in a conventional manner by a support 10 fixed to the casing 3.
  • a stator 11 is arranged outside the casing 3 and causes the rotation of the rotor 8, and consequently the rotation of the anode 5 around its axis of symmetry 9.
  • the cathode 4 is also carried in a conventional manner by the envelope 3 facing the periphery or edge 12 of the anode disc 5.
  • the cathode 4 delivers an electron beam 13 which bombards a target 30 which, in the nonlimiting example described, is formed on the wafer 12.
  • the anode 5 being a rotating anode, the target 30 constitutes a focal track along of the wafer 12 and around the axis of symmetry 9.
  • the electron beam 13 bombards the target 30 on a limited surface 15 of the latter, called focal point and which constitutes the source of X-radiation.
  • the target 30, bombarded by the electron beam 13 consists of molybdenum alloyed with vanadium or doped with vanadium in a proportion of at least 0.5% by weight. This makes it possible to delay and significantly reduce the aging of the target 30 and the cracking of the latter, under the effect of the bombardment of the electron beam 13, as it was previously mentioned.
  • vanadium is mixed with molybdenum in a proportion, by weight, of between 2.5 and 3.5%; an excess of vanadium (from 7% for example) which can lead to a non-negligible reduction in the intensity of the X-ray after filtration, if a filtration of the X-ray leaving the tube 1 is carried out to obtain that the energy spectrum of the X-ray covers a relatively narrow band containing the characteristic lines of molybdenum.
  • this filtration is carried out at an outlet window 33, by which the X-ray radiation leaves the sheath 2 after having left the tube 1 through a first outlet window 32 which is not very absorbent of the X-ray radiation.
  • the first outlet window 32 being, for example, conventionally, in beryllium, and the second window 33 in molybdenum.
  • Target 12 can be achieved in different ways: -
  • the target 30 can be formed for example directly by the anode 5 itself which is then produced in a massive manner in molybdenum doped with vanadium in the proportions specified above; the anode 5 being able to be produced in this case for example, by sintering, in itself known, of molybdenum powder with which the vanadium is mixed; - But the target 30 can be produced in the form of a layer 40 of the molybdenum-vanadium mixture, this layer 40 being deposited at the desired location on the anode disc 5 which, in this case, constitutes a basic body formed for example of molybdenum.
  • the layer 40 of molybdenum-vanadium can be deposited with a thickness E of a few micrometers for example, using a method in itself conventional, such as for example by an electrolytic deposition process, or a deposition process chemical vapor phase in which a mixture of the gaseous compounds of molybdenum and vanadium is produced in proportions such that, taking into account the kinetics of the reactions, and the experimental conditions (temperature, pressure, rate of introduction of the gases, etc. ..), the desired proportions at the level of the deposit are achieved.
  • the X-rays leaving the sheath 2 pass conventionally through a collimator 41, and then constitutes a useful X-rays 43 having limits 45, 46.
  • the first limit 45 which is situated on the side of the cathode 4 represents the limit of the X-ray beam 43 which, in mammography, is generally situated towards the costal grill of the patient (not shown); while on the side of anode 5, the second limit 46 represents the beam limit located towards the end or mammal of a breast to be examined.
  • the second limit 46 forms with the anode plane constituted by the edge 12, a relatively small angle ⁇ of the order for example of 2 °, and the drop in efficiency previously mentioned is a characteristic of the X-ray radiation 43 between the two limits 45, 46; that is, the intensity of the X-ray increases from the second limit 46 to the first limit 45, in a way which tends to compensate for the variations in absorption of the X-ray by the breast (not shown ) due to variations in thickness of the latter between the mammal and the costal grill.
  • a curve 50 illustrates by way of nonlimiting example, the variation in intensity of the radiation between the two limits 45,46; the curve 50 expresses its variations in percentage of a maximum intensity which the X-ray has along the first limit 45: it is observed by following the curve 50, that the intensity of the X-ray which is 100% at the level of the first limit 45, decreases with an increasingly steep slope, up to approximately 65% at the level of the second limit 46.
  • this target is practically not cracked, either that this target consists of molybdenum doped with vanadium according to the invention, or that this target is made of pure molybdenum having been very little subjected to electronic bombardment.
  • a second curve 51 in dotted lines, illustrates the modifications exhibited by the intensity of the X-radiation, under the same conditions as in the example above, but for a molybdenum target according to the prior art and whose aging under the effect of the electronic bombardments led to its cracking: we observe that the intensity of the X-radiation at the level of the first limit 45 is approximately 80%, that is to say that it is reduced by approximately 20 %, and the second curve 51 shows that the intensity of the X-ray decreases with a much steeper slope than in the first case for reach 25% at the second limit 46.

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  • X-Ray Techniques (AREA)
  • Apparatus For Radiation Diagnosis (AREA)
  • Solid Thermionic Cathode (AREA)
  • External Artificial Organs (AREA)

Abstract

An X-ray tube, the anode of which has a molybdenum target, is disclosed. In odrer to prevent cracks from forming in the target under the effect of electron bombardment, the molybedenum is alloyed with vanadium.

Description

L'invention concerne un tube à rayons x, notamment pour mammographie, et concerne particulièrement une cible d'anode en molybdène.The invention relates to an x-ray tube, in particular for mammography, and particularly relates to a molybdenum anode target.

Avec un tube à rayons X, le rayonnement X est obtenu sous l'effet d'un bombardement électronique d'une cible portée par l'anode, ou formée de l'anode elle-même. Sur la cible, une faible surface est soumise au bombardement électronique et constitue la source d'un rayonnement X. Les caractéristiques du rayonnement X dépendent des caractéristiques du faisceau d'électrons incidents, et de la nature du matériau dont est constituée la cible.With an X-ray tube, X-radiation is obtained under the effect of an electronic bombardment of a target carried by the anode, or formed from the anode itself. On the target, a small surface is subjected to electronic bombardment and constitutes the source of X-ray radiation. The characteristics of X-ray radiation depend on the characteristics of the incident electron beam, and on the nature of the material of which the target is made.

Les cibles en molybdène sont couramment utilisées dans les anodes de tube à rayons X destinés à la mammographie.Molybdenum targets are commonly used in X-ray tube anodes for mammography.

L'intérêt d'une cible en molybdène, dans la domaine de la mammographie, réside notamment dans le fait que le spectre en énergie du rayonnement X émis par le molybdène convient particulièrement bien à la spécificité d'un examen radiologique du sein. En effet, le sein a une absorption aux X faible, et les anomalies recherchées ont des densités très proches de celles des tissus environnants. Le contraste présenté sur une radiographie, entre ces anomalies et les tissus environnants, est amélioré de façon considérable quand le rayonnement X utilisé présente une bande étroite en énergie contenant les raies caractéristiques du molybdène.The interest of a molybdenum target, in the field of mammography, lies in particular in the fact that the energy spectrum of the X-radiation emitted by molybdenum is particularly suitable for the specificity of a radiological examination of the breast. Indeed, the breast has a low absorption at X, and the anomalies sought have densities very close to those of the surrounding tissues. The contrast presented on an X-ray, between these anomalies and the surrounding tissues, is improved considerably when the X-ray used has a narrow band of energy containing the characteristic lines of molybdenum.

Les cibles en molybdène sont couramment obtenues par un frittage de poudre de molybdène. Le plus souvent c'est l'anode elle-même qui est réalisée, de manière massive, par un frittage de poudre de molybdène, la cible étant constituée par une partie de l'anode ; l'anode pouvant être du type anode fixe ou du type anode tournante. D'autres méthodes classiques, telles que par exemple dépôt chimique en phase vapeur, ou encore depôt électrolytique permettent de déposer une couche de molybdène sur l'anode afin de constituer une cible sur tout ou partie de la surface de l'anode, selon une piste focale par exemple, dans le cas d'une anode tournante.Molybdenum targets are commonly obtained by sintering molybdenum powder. Most often it is the anode itself which is produced, in a massive manner, by a sintering of molybdenum powder, the target being constituted by a part of the anode; the anode may be of the fixed anode type or of the rotating anode type. Other conventional methods, such as for example chemical vapor deposition, or else electrolytic deposition make it possible to deposit a layer of molybdenum on the anode in order to constitute a target on all or part of the surface of the anode, according to a focal track for example, in the case of a rotating anode.

Les bombardements électroniques répétés auxquels est soumise la cible en molybdène, crééent dans cette dernière des contraintes thermo-mécaniques qui provoquent la fissuration du molybdène. Les fissures croissent en nombre et en importance avec le nombre de poses effectuées. Ces fissures entraînent une diminution du rendement en rayons X du tube radiogène. Ceci peut s'expliquer par le fait que des électrons qui tombent dans les fissures créent des rayons X qui, pour une part importante, sont absorbés dans l'anode elle-même.The repeated electronic bombardments to which the molybdenum target is subjected, create thermo-mechanical stresses in the latter which cause cracking of the molybdenum. The cracks grow in number and in importance with the number of poses carried out. These cracks cause a decrease in the x-ray yield of the X-ray tube. This can be explained by the fact that electrons which fall into the cracks create X-rays which, for a large part, are absorbed in the anode itself.

La baisse de rendement en rayonnement X conduit notamment aux deux inconvénients suivants, particulièrement importants dans le cas de la mammographie :

  • - 1° : une détérioration de la qualité d'image qui s'explique, d'une part, par une augmentation du flou cinétique ou flou de bougé, due à l'augmentation des temps d'exposition nécessitée par la baisse de rendement en rayonnement X ; et qui s'explique d'autre part, par une inhomogénéïté en densité du cliché, due à une accentuation d'un phénomène de variations de rendement de rayonnement X dans le champ.
  • - 2° : une augmentation de la dose reçue par la patiente par suite de l'écart de la loi dite de réciprocité du couple film/écran utilisé en mammographie : en effet, la non-réciprocité du récepteur (film/écran) fait que la quantité de photons, nécessaire au noircissement du film, croît lorsque les temps d'exposition augmentent.
The drop in X-ray yield leads in particular to the following two drawbacks, which are particularly important in the case of mammography:
  • - 1 °: a deterioration of the image quality which is explained, on the one hand, by an increase in kinetic blurring or blurring of camera shake, due to the increase in exposure times necessitated by the drop in yield in X-ray; and which is explained on the other hand, by an inhomogeneity in density of the photograph, due to an accentuation of a phenomenon of variations of yield of X-ray radiation in the field.
  • - 2 °: an increase in the dose received by the patient as a result of the deviation from the so-called reciprocity law of the film / screen couple used in mammography: in fact, the non-reciprocity of the receiver (film / screen) means that the quantity of photons necessary for the blackening of the film increases with increasing exposure times.

Ainsi par exemple dans une direction voisine de celle où l'intensité du rayonnement X est maximum, cette intensité est diminuée d'environ 20% après trois mois de fonctionnement normal du tube radiogène, et elle est diminuée d'environ 40% dans un plan voisin du plan d'anode.Thus for example in a direction close to that where the intensity of the X-ray radiation is maximum, this intensity is reduced by approximately 20% after three months of normal operation of the X-ray tube, and it is reduced by approximately 40% in a plane near the anode plane.

La présente invention concerne un tube radiogène à anode fixe ou anode tournante, particulièrement mais non exclusivement destiné à la mammographie, l'anode ayant une cible en molybdène qui ne présente pas les problèmes de fissuration ci-dessus mentionnés ou éventuellement au bout d'un temps de fonctionnement beaucoup plus long et à un dégré beaucoup plus faible qu'avec une cible en molybdène selon l'art antérieur.The present invention relates to an X-ray tube with fixed anode or rotating anode, particularly but not exclusively intended for mammography, the anode having a molybdenum target which does not exhibit the above-mentioned cracking problems or possibly after a much longer operating time and at a much lower degree than with a molybdenum target according to the prior art.

Ceci est obtenu par un dopage du molybdène. Nous pensons que ce dopage a pour effet de renforcer la liaison inter-granulaire et les grains eux-mêmes du molybdène et de rendre ce dernier plus élastique.This is achieved by doping molybdenum. We believe that this doping has the effect of strengthening the inter-granular bond and the grains themselves of molybdenum and making the latter more elastic.

Selon l'invention, un tube radiogène comportant une anode et une cathode, la cathode délivrant un faisceau d'électrons, l'anode comportant une cible bombardée par le faisceau d'électrons sur une surface constituant la source d'un rayonnement X, la cible étant constituée en molybdène, est caractérisé en ce que le molybdène est allié à du vanadium.According to the invention, an X-ray tube comprising an anode and a cathode, the cathode delivering an electron beam, the anode comprising a target bombarded by the electron beam on a surface constituting the source of X-radiation, the target being made of molybdenum, is characterized in that the molybdenum is alloyed with vanadium.

Nous avons constaté en outre que le dopage du molybdène avec du vanadium présente un avantage important dans le cas d'un tube radiogène utilisé en mammographie, et qui réside en ce que les raies caractéristiques du vanadium émises sous le bombardement électronique, sont totalement éliminées par une filtration classique du rayonnement X émis par le tube radiogène, de sorte que le spectre du rayonnement X n'est pas modifié par la présence du vanadium.We have also found that doping molybdenum with vanadium has an important advantage in the case of an X-ray tube used in mammography, and which resides in that the lines characteristic of vanadium emitted under electron bombardment, are completely eliminated by conventional filtration of the X-rays emitted by the X-ray tube, so that the X-ray spectrum is not modified by the presence of vanadium.

L'invention sera mieux comprise grâce à la description qui suit, faite à titre d'exemple non limitatif, et à l'unique figure jointe qui montre de manière schématique un tube à rayons X conforme à l'invention.The invention will be better understood thanks to the description which follows, given by way of nonlimiting example, and to the single appended figure which schematically shows an X-ray tube according to the invention.

La figure montre à titre d'exemple non limitatif, un tube radiogène 1 conforme à l'invention, particulièrement destiné à une application à la mammographie.The figure shows by way of nonlimiting example, an X-ray tube 1 according to the invention, particularly intended for application to mammography.

Le tube radiogène 1 est contenu de manière classique dans une gaine 2. Le tube radiogène 1 comporte une enveloppe 3 en verre par exemple, contenant notamment une cathode 4 et une anode 5. Dans l'exemple non limitatif décrit, l'anode 5 est une anode tournante ayant la forme générale d'un disque, et qui est portée au centre du disque par un arbre support 7 solidaire d'un rotor 8. Le rotor 8 est disposé selon un axe de symétrie 9 du disque d'anode 5 ; le rotor 8 étant lui-même porté de manière classique par un support 10 fixé à l'enveloppe 3. Un stator 11 est disposé à l'extérieur de l'enveloppe 3 et provoque la rotation du rotor 8, et par suite la rotation de l'anode 5 autour de son axe de symétrie 9. La cathode 4 est également portée de manière conventionnelle par l'enveloppe 3 en vis à vis du pourtour ou tranche 12 du disque d'anode 5.The X-ray tube 1 is conventionally contained in a sheath 2. The X-ray tube 1 comprises an envelope 3 made of glass for example, containing in particular a cathode 4 and an anode 5. In the nonlimiting example described, the anode 5 is a rotating anode having the general shape of a disc, and which is carried in the center of the disc by a support shaft 7 secured to a rotor 8. The rotor 8 is arranged along an axis of symmetry 9 of the anode disc 5; the rotor 8 itself being carried in a conventional manner by a support 10 fixed to the casing 3. A stator 11 is arranged outside the casing 3 and causes the rotation of the rotor 8, and consequently the rotation of the anode 5 around its axis of symmetry 9. The cathode 4 is also carried in a conventional manner by the envelope 3 facing the periphery or edge 12 of the anode disc 5.

La cathode 4 délivre un faisceau d'électrons 13 qui bombarde une cible 30 qui, dans l'exemple non limitatif décrit, est formée sur la tranche 12. L'anode 5 étant une anode tournante, la cible 30 constitue une piste focale le long de la tranche 12 et autour de l'axe de symétrie 9. Le faisceau d'électrons 13 bombarde la cible 30 sur une surface limitée 15 de cette dernière, appelée foyer et qui constitue la source d'un rayonnement X.The cathode 4 delivers an electron beam 13 which bombards a target 30 which, in the nonlimiting example described, is formed on the wafer 12. The anode 5 being a rotating anode, the target 30 constitutes a focal track along of the wafer 12 and around the axis of symmetry 9. The electron beam 13 bombards the target 30 on a limited surface 15 of the latter, called focal point and which constitutes the source of X-radiation.

Selon une caractéristique de l'invention, la cible 30, bombardée par le faisceau d'électrons 13, est constituée en molybdène allié à du vanadium ou dopé avec du vanadium dans une proportion d'au moins 0,5% en poids. Ceci permet de retarder et de diminuer de manière importante le vieillissement de la cible 30 et la fissuration de cette dernière, sous l'effet du bombardement du faisceau d'électrons 13, comme il a été précédemment mentionné. On constate une amélioration importante à partir de 0,5% en poids de vanadium, l'optimum étant que le vanadium soit mélangé au molybdène dans une proportion, en poids, comprise entre 2,5 et 3,5% ; un excès de vanadium (à partir de 7% par exemple) pouvant conduire à une diminution non négligeable de l'intensité du rayonnement X après filtration, si une filtration du rayonnement X sortant du tube 1 est réalisée pour obtenir que le spectre en énergie du rayonnement X couvre une bande relativement étroite contenant les raies caractéristiques du molybdène.According to a characteristic of the invention, the target 30, bombarded by the electron beam 13, consists of molybdenum alloyed with vanadium or doped with vanadium in a proportion of at least 0.5% by weight. This makes it possible to delay and significantly reduce the aging of the target 30 and the cracking of the latter, under the effect of the bombardment of the electron beam 13, as it was previously mentioned. There is a significant improvement from 0.5% by weight of vanadium, the optimum being that the vanadium is mixed with molybdenum in a proportion, by weight, of between 2.5 and 3.5%; an excess of vanadium (from 7% for example) which can lead to a non-negligible reduction in the intensity of the X-ray after filtration, if a filtration of the X-ray leaving the tube 1 is carried out to obtain that the energy spectrum of the X-ray covers a relatively narrow band containing the characteristic lines of molybdenum.

Dans l'exemple non limitatif décrit, cette filtration est réalisée au niveau d'une fenêtre de sortie 33, par laquelle le rayonnement X sort de la gaine 2 après être sorti du tube 1 par une première fenêtre de sortie 32 peu absorbante du rayonnement X ; la première fenêtre de sortie 32 étant par exemple, de manière classique, en béryllium, et la seconde fenêtre 33 en molybdène.In the nonlimiting example described, this filtration is carried out at an outlet window 33, by which the X-ray radiation leaves the sheath 2 after having left the tube 1 through a first outlet window 32 which is not very absorbent of the X-ray radiation. ; the first outlet window 32 being, for example, conventionally, in beryllium, and the second window 33 in molybdenum.

La cible 12 peut être réalisée de différentes façons :
- la cible 30 peut être formée par exemple directement par l'anode 5 elle-même qui est alors réalisée de manière massive en molybdène dopé de vanadium dans les proportions ci-dessus précisées ; l'anode 5 pouvant être réalisée dans ce cas par exemple, par un frittage, en lui-même connu, de poudre de molybdène à laquelle est mélangé le vanadium ;
- mais la cible 30 peut être réalisée sous la forme d'une couche 40 du mélange molybdène-vanadium, cette couche 40 étant déposée à l'emplacement désiré sur le disque d'anode 5 qui, dans ce cas, constitue un corps de base formé par exemple en molybdène. La couche 40 de molybdène-vanadium peut être déposée avec une épaisseur E de quelques micromètres par exemple, à l'aide d'une méthode en elle-même classique, telle que par exemple par un procédé de dépôt électrolytique, ou un procédé de dépôt chimique en phase vapeur dans lequel est réalisé un mélange des composés gazeux de molybdène et de vanadium dans des proportions telles que, compte tenu de la cinétique des réactions, et des conditions expérimentales (température, pression, vitesse d'introduction des gaz, etc...), les proportions voulues au niveau du dépôt soient réalisées.Target 12 can be achieved in different ways:
- The target 30 can be formed for example directly by the anode 5 itself which is then produced in a massive manner in molybdenum doped with vanadium in the proportions specified above; the anode 5 being able to be produced in this case for example, by sintering, in itself known, of molybdenum powder with which the vanadium is mixed;
- But the target 30 can be produced in the form of a layer 40 of the molybdenum-vanadium mixture, this layer 40 being deposited at the desired location on the anode disc 5 which, in this case, constitutes a basic body formed for example of molybdenum. The layer 40 of molybdenum-vanadium can be deposited with a thickness E of a few micrometers for example, using a method in itself conventional, such as for example by an electrolytic deposition process, or a deposition process chemical vapor phase in which a mixture of the gaseous compounds of molybdenum and vanadium is produced in proportions such that, taking into account the kinetics of the reactions, and the experimental conditions (temperature, pressure, rate of introduction of the gases, etc. ..), the desired proportions at the level of the deposit are achieved.

Le rayonnement X sortant de la gaine 2 passe de manière classique par un collimateur 41, et constitue alors un rayonnement X utile 43 ayant des limites 45,46. La première limite 45, qui est située du côté de la cathode 4 représente la limite du faisceau X 43 qui, en mammographie, est généralement située vers le gril costal de la patiente (non représentée) ; alors que du côté de l'anode 5, la seconde limite 46 représente la limite du faisceau située vers l'extrémité ou mammelon d'un sein à examiner. La seconde limite 46 forme avec le plan d'anode constitué par la tranche 12, une angle α relativement faible de l'ordre par exemple de 2°, et la baisse de rendement précédemment mentionnée est une caractéristique du rayonnement X 43 entre les deux limites 45, 46 ; c'est-à-dire que l'intensité du rayonnement X augmente depuis la seconde limite 46 jusqu'à la première limite 45, d'une manière qui tend à compenser les variations d'absorption du rayonnement X par le sein (non représenté) dues aux variations d'épaisseur de ce dernier entre le mammelon et le gril-costal.The X-rays leaving the sheath 2 pass conventionally through a collimator 41, and then constitutes a useful X-rays 43 having limits 45, 46. The first limit 45, which is situated on the side of the cathode 4 represents the limit of the X-ray beam 43 which, in mammography, is generally situated towards the costal grill of the patient (not shown); while on the side of anode 5, the second limit 46 represents the beam limit located towards the end or mammal of a breast to be examined. The second limit 46 forms with the anode plane constituted by the edge 12, a relatively small angle α of the order for example of 2 °, and the drop in efficiency previously mentioned is a characteristic of the X-ray radiation 43 between the two limits 45, 46; that is, the intensity of the X-ray increases from the second limit 46 to the first limit 45, in a way which tends to compensate for the variations in absorption of the X-ray by the breast (not shown ) due to variations in thickness of the latter between the mammal and the costal grill.

Une courbe 50 illustre à titre d'exemple non limitatif, la variation en intensité du rayonnement entre les deux limites 45,46 ; la courbre 50 exprime ses variations en pourcentage d'une intensité maximum que possède le rayonnement X le long de la première limite 45 : on observe en suivant la courbe 50, que l'intensité du rayonnement X qui est de 100% au niveau de la première limite 45, diminue avec une pente de plus en plus accentuée, jusqu'à environ 65% au niveau de la seconde limite 46.A curve 50 illustrates by way of nonlimiting example, the variation in intensity of the radiation between the two limits 45,46; the curve 50 expresses its variations in percentage of a maximum intensity which the X-ray has along the first limit 45: it is observed by following the curve 50, that the intensity of the X-ray which is 100% at the level of the first limit 45, decreases with an increasingly steep slope, up to approximately 65% at the level of the second limit 46.

Ceci correspond au cas où la cible n'est pratiquement pas fissurée, soit que cette cible soit constituée de molybdène dopé avec du vanadium conformément à l'invention, soit que cette cible soit en molybdène pur ayant été très peu soumise à un bombardement électronique.This corresponds to the case where the target is practically not cracked, either that this target consists of molybdenum doped with vanadium according to the invention, or that this target is made of pure molybdenum having been very little subjected to electronic bombardment.

Une seconde courbe 51, en traits pointillés, illustre les modifications accusées par l'intensité du rayonnement X, dans les mêmes conditions que dans l'exemple ci-dessus, mais pour une cible en molybdène selon l'art antérieur et dont le vieillissement sous l'effet des bombardements électroniques a conduit à sa fissuration : on observe que l'intensité du rayonnement X au niveau de la première limite 45 est à environ 80%, c'est-à-dire qu'il est réduit d'environ 20%, et la seconde courbe 51 montre que l'intensité du rayonnement X diminue avec une pente beaucoup plus accentuée que dans le premier cas pour atteindre 25% au niveau de la seconde limite 46.A second curve 51, in dotted lines, illustrates the modifications exhibited by the intensity of the X-radiation, under the same conditions as in the example above, but for a molybdenum target according to the prior art and whose aging under the effect of the electronic bombardments led to its cracking: we observe that the intensity of the X-radiation at the level of the first limit 45 is approximately 80%, that is to say that it is reduced by approximately 20 %, and the second curve 51 shows that the intensity of the X-ray decreases with a much steeper slope than in the first case for reach 25% at the second limit 46.

Ceci montre qu'une cible 30 réalisée en mobybdène allié à ou dopé avec du vanadium, conformément à l'invention, permet en évitant les fissurations de la cible dues aux bombardements électroniques répétés, d'éviter une réduction importante de l'intensité du rayonnement X et de son évolution dans le champ, ces deux inconvénients étant particulièrement graves pour un tube radiogène de mammographie.This shows that a target 30 made of mobybdenum alloyed with or doped with vanadium, in accordance with the invention, makes it possible, by avoiding cracking of the target due to repeated electronic bombardment, to avoid a significant reduction in the intensity of the radiation. X and its development in the field, these two drawbacks being particularly serious for an X-ray tube for mammography.

Claims (7)

1. Tube radiogène comportant une anode (5) et une cathode (4), la cathode (4) délivrant un faisceau d'électrons (13), l'anode (5) comportant une cible (30) bombardée par le faisceau d'électrons (13) sur une surface (15) constituant la source d'un rayonnement X (43), la cible (30) étant constituée en molybdène, caractérisé en ce que le molybdène est allié à du vanadium dans une proportion, en poids, d'au moins 0,5%.1. X-ray tube comprising an anode (5) and a cathode (4), the cathode (4) delivering an electron beam (13), the anode (5) comprising a target (30) bombarded by the beam of electrons (13) on a surface (15) constituting the source of X-ray radiation (43), the target (30) being made of molybdenum, characterized in that the molybdenum is alloyed with vanadium in a proportion, by weight, at least 0.5%. 2. Tube radiogène selon la revendication 1, caractérisé en ce que le vanadium est allié au molybdène dans une proportion, en poids, comprise entre 2,5 et 3,5%.2. X-ray tube according to claim 1, characterized in that the vanadium is alloyed with molybdenum in a proportion, by weight, between 2.5 and 3.5%. 3. Tube radiogène selon l'une des revendications précédentes, caractérisé en ce que la cible (30) est formée directement par l'anode (5), l'anode (5) étant réalisée par frittage d'une poudre de molybdène à laquelle est mélangée du vanadium.3. X-ray tube according to one of the preceding claims, characterized in that the target (30) is formed directly by the anode (5), the anode (5) being produced by sintering a molybdenum powder to which is mixed with vanadium. 4. Tube radiogène selon l'une des revendications 1 ou 2, caractérisé en ce que l'anode (5) comporte un corps de base sur lequel la cible (30) est déposée sous la forme d'une couche (40).4. X-ray tube according to one of claims 1 or 2, characterized in that the anode (5) comprises a base body on which the target (30) is deposited in the form of a layer (40). 5. Tube radiogène selon l'une quelconque des revendications précédentes, caractérisé en ce que le dépôt(40) de la couche formant la cible (30) est réalisé par un procédé de dépôt chimique en phase vapeur.5. X-ray tube according to any one of the preceding claims, characterized in that the deposition (40) of the layer forming the target (30) is produced by a chemical vapor deposition process. 6. Tube radiogène selon l'une des revendications précédentes, caractérisé en ce que l'anode (5) est une anode tournante.6. X-ray tube according to one of the preceding claims, characterized in that the anode (5) is a rotating anode. 7. Tube radiogène selon l'une des revendications précédentes, caractérisé en ce qu'il constitue le tube radiogène d'un appareil de mammographie.7. X-ray tube according to one of the preceding claims, characterized in that it constitutes the x-ray tube of a mammography device.
EP88402830A 1987-11-13 1988-11-10 X-ray tube having a molybdenum target Expired - Lifetime EP0317402B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT88402830T ATE77176T1 (en) 1987-11-13 1988-11-10 X-RAY TUBE WITH A MOLYBDEN TARGET.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8715671 1987-11-13
FR8715671A FR2623331A1 (en) 1987-11-13 1987-11-13 X-RAY TUBE HAVING A MOLYBDENE TARGET

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EP0317402A1 true EP0317402A1 (en) 1989-05-24
EP0317402B1 EP0317402B1 (en) 1992-06-10

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US (1) US4876705A (en)
EP (1) EP0317402B1 (en)
JP (1) JP2731803B2 (en)
AT (1) ATE77176T1 (en)
DE (1) DE3871913T2 (en)
FR (1) FR2623331A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023043340A1 (en) 2021-09-17 2023-03-23 Общество С Ограниченной Ответственностью "Пробиодукты" Plant-based probiotic composition and method of producing same

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04118841A (en) * 1990-05-16 1992-04-20 Toshiba Corp Rotary anode x-ray tube and manufacture thereof
US5592525A (en) * 1994-11-30 1997-01-07 General Electric Company Method for making a rotating anode with an integral shaft
US5647775A (en) * 1995-12-07 1997-07-15 Molex Incorporated Electrical connector with terminal locking means
US7180981B2 (en) 2002-04-08 2007-02-20 Nanodynamics-88, Inc. High quantum energy efficiency X-ray tube and targets
US6798865B2 (en) * 2002-11-14 2004-09-28 Ge Medical Systems Global Technology HV system for a mono-polar CT tube
US6925152B2 (en) * 2003-05-13 2005-08-02 Ge Medical Systems Global Technology Co., Llc Target attachment assembly
EP1953254B1 (en) * 2005-10-27 2012-12-26 Kabushiki Kaisha Toshiba X-ray tube rotating anode target and x-ray tube
US8284899B2 (en) * 2007-11-21 2012-10-09 Varian Medical Systems, Inc. X-ray tube having a focal spot proximate the tube end

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2349953A1 (en) * 1976-04-26 1977-11-25 Siemens Ag ROTATING ANODE FOR X-RAY TUBE
FR2500958A1 (en) * 1981-03-02 1982-09-03 Siemens Ag ROTATING ANODE FOR RADIOGENIC TUBES
US4641334A (en) * 1985-02-15 1987-02-03 General Electric Company Composite rotary anode for X-ray tube and process for preparing the composite

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2231686A1 (en) * 1972-06-28 1974-01-17 Siemens Ag ROTARY ROTARY ANODE
FR2386132A1 (en) * 1977-03-29 1978-10-27 Eurotungstene ROTATING ANODE FOR RADIOGENIC TUBE
JPS60250546A (en) * 1984-05-28 1985-12-11 Hitachi Ltd Rotor for x-ray tube

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2349953A1 (en) * 1976-04-26 1977-11-25 Siemens Ag ROTATING ANODE FOR X-RAY TUBE
FR2500958A1 (en) * 1981-03-02 1982-09-03 Siemens Ag ROTATING ANODE FOR RADIOGENIC TUBES
US4641334A (en) * 1985-02-15 1987-02-03 General Electric Company Composite rotary anode for X-ray tube and process for preparing the composite

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, vol. 10, no. 117 (E-400)[2174], 2 mai 1986, page 14 E 400; & JP-A-60 250 546 (HITACHI SEISAKUSHO K.K.) 11-12-1985 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023043340A1 (en) 2021-09-17 2023-03-23 Общество С Ограниченной Ответственностью "Пробиодукты" Plant-based probiotic composition and method of producing same

Also Published As

Publication number Publication date
FR2623331B1 (en) 1995-02-10
ATE77176T1 (en) 1992-06-15
JP2731803B2 (en) 1998-03-25
DE3871913T2 (en) 1993-01-14
JPH01281644A (en) 1989-11-13
DE3871913D1 (en) 1992-07-16
EP0317402B1 (en) 1992-06-10
FR2623331A1 (en) 1989-05-19
US4876705A (en) 1989-10-24

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