EP0397562B1 - Safety device for X-ray installation - Google Patents

Safety device for X-ray installation Download PDF

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Publication number
EP0397562B1
EP0397562B1 EP90401231A EP90401231A EP0397562B1 EP 0397562 B1 EP0397562 B1 EP 0397562B1 EP 90401231 A EP90401231 A EP 90401231A EP 90401231 A EP90401231 A EP 90401231A EP 0397562 B1 EP0397562 B1 EP 0397562B1
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EP
European Patent Office
Prior art keywords
cathode
ray
detector
tube
safety device
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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.)
Expired - Lifetime
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EP90401231A
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German (de)
French (fr)
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EP0397562A1 (en
Inventor
Jacques Le Guen
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General Electric CGR SA
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General Electric CGR SA
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    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05GX-RAY TECHNIQUE
    • H05G1/00X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08Electrical details
    • H05G1/26Measuring, controlling or protecting
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05GX-RAY TECHNIQUE
    • H05G1/00X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/02Constructional details
    • H05G1/025Means for cooling the X-ray tube or the generator
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05GX-RAY TECHNIQUE
    • H05G1/00X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/02Constructional details
    • H05G1/04Mounting the X-ray tube within a closed housing
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05GX-RAY TECHNIQUE
    • H05G1/00X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08Electrical details
    • H05G1/26Measuring, controlling or protecting
    • H05G1/54Protecting or lifetime prediction

Definitions

  • the energy dissipated in such a tube is high and it is therefore planned to cool it.
  • the tube is enclosed in an enclosure in which a cooling fluid, in particular oil, is circulated.
  • the fluid is itself cooled in an exchanger which can be of the air or water type.
  • a cooling device has thus been produced which operates continuously.
  • the X-ray tube only emits intermittently so that the dissipated energy is important during the examination phase itself, from a few seconds to a few minutes, and that it is practically zero during the rest time necessary to change the patient. This results in significant disparities in the quantity of heat to be removed depending on the phase considered, which in particular leads to significant variations in the temperatures of the materials of the tube used, variations which can adversely affect the proper functioning of the tube.
  • the ducts are equipped with alarm devices which detect an excessive increase in the volume of the enclosure, that is to say a displacement of the expansion membrane, and provide a signal of alarm, for example using a microswitch associated with said membrane.
  • Other alarm devices measure the temperature or the pressure and provide an alarm signal when the measured values exceed a certain threshold.
  • An object of the present invention is therefore to provide a safety device the action of which is independent of the cut-off device of the high-voltage generator, which eliminates the risks resulting from the failure of the latter.
  • Another object of the present invention is to provide a security device which cannot be deactivated by the users.
  • the invention relates to a safety device for an X-ray assembly of a radiology device which comprises on the one hand, an X-ray tube enclosed in a sheath filled with a coolant, said tube comprising a carried anode at a high voltage by a voltage generator and a cathode, comprising at least one filament connected to an electrical supply circuit, and on the other hand, at least one device sensitive to temperature or to pressure which is placed inside the sheath, characterized in that the switch of said switch device is connected in series in the electrical supply circuit of the cathode filament so that only the electrical supply of the filament is cut off when the temperature or the pressure exceeds a predetermined threshold and in that it further comprises a device for cutting off the voltage generator which is controlled by a cathode supply current or X-ray detector.
  • FIG. 1 there is shown an X-ray tube 11 which is disposed in a cooling sheath 12.
  • the X-ray tube 11 has a glass envelope 13 in which is produced a high vacuum. Inside this envelope 13 are arranged an emissive cathode 14 and an anode 15 which, in the particular case, is rotating.
  • the anode 15 is mounted at the end of a rotor 16 which cooperates with a stator 17 placed outside the casing 13.
  • the cooling sheath 12 is for example made by the tight assembly of four parts referenced 18,19,20 and 21.
  • Part 18, which is substantially central, carries the exit window 22 for X-ray radiation.
  • the end parts 20 and 21 are closed at their ends and bear one one inlet port 23 for the coolant and the other an outlet port 24 for this liquid.
  • Parts 18 and 20 are connected through part 19.
  • the cooling fluid circulates in the space 25 between the envelope 13 and the internal walls of the sheath 12 and is therefore in contact with the glass envelope 13 so as to cool it.
  • the electric power cables of the X-ray tube penetrate into the sheath 12 through the orifice 29 for the cathode 14 and the orifice 30 for the anode 15.
  • These orifices 29 and 30 are fitted with insulating pads 31 and 32 of cylindrical shape which are tightly mounted.
  • These studs end inside the sheath by electrical terminals 26, 27 and 28 for the stud 31 and 33, 34 35 and 48 for the stud 32.
  • these electrical terminals are connected to the conductors of each power supply cable.
  • the electrical terminals 26, 27 and 28 are connected to the cathode 14 composed of two filaments 39 and 40 by three electrical conductors 36, 37 and 38.
  • the electrical terminal 48 is connected so as to bring the rotating anode 15 to a high positive voltage with respect to the cathode, the latter being at a negative voltage. Furthermore, the electrical terminals 33, 34 and 35 are connected to the stator 17 of the motor.
  • the safety device mainly consists of a thermostat and / or a pressure switch which is connected in series in the circuit electric supply of the cathode filament (s) and which is placed in the coolant of the sheath enclosure.
  • the electrical terminals 26, 27 and 28, on the one hand and 33, 34 and 48 and 48, on the other hand, are respectively connected to a supply device 41 by means of conductors 26 ′, 27 'and 28' for the cathode electrical cable and 33 ', 34' 35 'and 48' for the anode electrical cable.
  • the thermostat or the pressure switch is connected in series in the common conductor 37 and is referenced 42. From the electrical point of view, it is a switch 43 which is normally closed and which opens when the temperature and / or the pressure exceeds a certain threshold. From the mechanical point of view, it is disposed in the sheath and carried either by the stud 31, or by the base of the cathode.
  • the safety device has only one element, a thermostat or a pressure switch but you can connect a thermostat and a pressure switch in series so as to increase safety in case of failure of the a. Furthermore, when only one device is used, it is preferable use a pressure switch because it can detect an overpressure in the coolant whereas a thermostat may not detect a localized temperature increase anywhere in the duct.
  • the operation of the safety device according to the invention is simple: as soon as the temperature and / or the pressure exceeds the setting threshold of the thermostat and / or the pressure switch, the switch 43 opens and the filament 39 or 40 which was powered no longer is. As a result, there is no longer any emission of electrons or X-rays, this emission of electrons being the main source of the heating of the tube-coolant-sheath assembly.
  • the invention provides a device for detecting the absence of emission of electrons and X-rays so as to cut off the high voltage generator.
  • This detection device can be constituted by a cathode current detector arranged outside the sheath on the low voltage part of the heating transformer 44.
  • a relay 46 which, in the event of cutting the cathode supply current during normal operation, controls the stopping of the high voltage by means of a contact 45 placed on the low voltage inlet of the transformer 47 high voltage supply.
  • the security device according to the invention could replace the safety devices, external to the sheath, which are currently used. However, it is preferable that this new safety device is added to the previous ones so as to constitute the last link of the safety system in case all the others have been faulty or neutralized.
  • the different triggering thresholds of the various safety devices must be provided so that the devices internal to the sheath, those of the invention, only trigger for values of temperature and / or pressure higher than those of the devices. exteriors.

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • X-Ray Techniques (AREA)

Description

L'invention concerne les appareils de radiologie et, plus particulièrement dans de tels appareils, un dispositif de sécurité pour l'ensemble radiogène comprenant la source de rayonnement X (tube) et les moyens assurant la protection contre les rayonnements ionisants et les chocs électriques.The invention relates to radiology devices and, more particularly in such devices, a safety device for the X-ray unit comprising the X-ray source (tube) and the means ensuring protection against ionizing radiation and electric shock.

Les tubes à rayons X, pour diagnostic médical par exemple, sont généralement constitués comme une diode, c'est-à-dire avec une cathode et une anode ou anti-cathode, ces deux électrodes étant enfermées dans une enveloppe étanche au vide qui permet de réaliser l'isolement électrique entre ces deux électrodes. La cathode produit un faisceau d'électrons et l'anode reçoit ces électrons sur une petite surface qui constitue un foyer d'où sont émis les rayons X.X-ray tubes, for medical diagnosis for example, are generally constituted as a diode, that is to say with a cathode and an anode or anti-cathode, these two electrodes being enclosed in a vacuum-tight envelope which allows to provide electrical isolation between these two electrodes. The cathode produces an electron beam and the anode receives these electrons on a small surface which constitutes a focus from which the X-rays are emitted.

Quand la haute tension d'alimentation est appliquée aux bornes de la cathode et de l'anode, de façon que la cathode soit au potentiel négatif, un courant dit courant anodique s'établit dans le circuit, au travers d'un générateur produisant la haute tension d'alimentation; le courant anodique traverse l'espace entre la cathode et l'anode sous la forme d'un faisceau d'électrons qui bombardent le foyer.When the high supply voltage is applied across the cathode and the anode, so that the cathode is at negative potential, a current called anodic current is established in the circuit, through a generator producing the high supply voltage; the anode current crosses the space between the cathode and the anode in the form of a beam of electrons which bombard the hearth.

Une faible proportion de l'énergie dépensée à produire le faisceau d'électrons est transformée en rayons X, le reste de cette énergie est transformée en chaleur. Aussi compte tenu également des puissances instantanées importantes mises en jeu, (de l'ordre de 100 kw) et des petites dimensions du foyer (de l'ordre du millimètre), les constructeurs ont depuis longtemps réalisé des tubes à rayons X à anodes tournantes où l'anode est mise en rotation pour répartir le flux thermique sur une couronne appelée couronne focale, d'aire beaucoup plus grande que le foyer, l'intérêt étant d'autant plus grand que la vitesse de rotation est élevée (en général entre 3.000 et 12.000 tours par minute).A small proportion of the energy expended in producing the electron beam is transformed into X-rays, the rest of this energy is transformed into heat. Also taking into account the large instantaneous powers involved, (of the order of 100 kw) and the small dimensions of the hearth (of the order of a millimeter), manufacturers have long produced tubes X-ray with rotating anodes where the anode is rotated to distribute the heat flux over a ring called focal ring, with an area much larger than the focal point, the advantage being all the greater as the speed of rotation is high (generally between 3,000 and 12,000 revolutions per minute).

L'anode tournante de type classique a la forme générale d'un disque, ayant un axe de symétrie autour duquel elle est mise en rotation à l'aide d'un moteur électrique; le moteur électrique a un stator situé à l'extérieur de l'enveloppe, et un rotor monté dans l'enveloppe du tube à rayons X et disposé selon l'axe de symétrie, le rotor étant mécaniquement solidarisé à l'anode par l'intermédiaire d'un arbre support.The rotary anode of the conventional type has the general shape of a disc, having an axis of symmetry about which it is rotated by means of an electric motor; the electric motor has a stator located outside the envelope, and a rotor mounted in the envelope of the X-ray tube and arranged along the axis of symmetry, the rotor being mechanically secured to the anode by the intermediate of a support shaft.

L'énergie dissipée dans un tel tube est élevée et il est donc prévu de le refroidir. Pour cela, le tube est enfermé dans une enceinte dans laquelle on fait circuler un fluide de refroidissement, notamment de l'huile. Le fluide est lui-même refroidi dans un échangeur qui peut être du type à air ou à eau. On a ainsi réalisé un dispositif de refroidissement qui fonctionne en permanence. Cependant, le tube à rayons X n'émet que par intermittence de sorte que l'énergie dissipée est importante pendant la phase d'examen proprement dite, de quelques secondes à quelques minutes, et qu'elle est pratiquement nulle pendant le temps de repos nécessaire au changement de patient. Il en résulte des disparités importantes de quantité de chaleur à évacuer selon la phase considérée, ce qui conduit notamment à des variations importantes des températures des matériaux du tube utilisés, variations qui peuvent nuire au bon fonctionnement du tube.The energy dissipated in such a tube is high and it is therefore planned to cool it. For this, the tube is enclosed in an enclosure in which a cooling fluid, in particular oil, is circulated. The fluid is itself cooled in an exchanger which can be of the air or water type. A cooling device has thus been produced which operates continuously. However, the X-ray tube only emits intermittently so that the dissipated energy is important during the examination phase itself, from a few seconds to a few minutes, and that it is practically zero during the rest time necessary to change the patient. This results in significant disparities in the quantity of heat to be removed depending on the phase considered, which in particular leads to significant variations in the temperatures of the materials of the tube used, variations which can adversely affect the proper functioning of the tube.

L'huile contenue dans l'enceinte de la gaine est donc soumise à des élévations de température qui ont pour effet de produire une dilatation du volume d'huile et, par conséquent, une surpression à l'intérieur de l'enceinte de ladite gaine. Pour tenir compte de cette dilatation dans la gamme de fonctionnemenent normal du tube, la gaine est équipée d'une membrane qui, en se déplaçant, augmente ou diminue le volume de l'enceinte contenant l'huile de refroidissement.The oil contained in the enclosure of the sheath is therefore subjected to temperature increases which have for effect of producing an expansion of the volume of oil and, consequently, an overpressure inside the enclosure of said sheath. To take account of this expansion in the normal operating range of the tube, the sheath is equipped with a membrane which, as it moves, increases or decreases the volume of the enclosure containing the cooling oil.

Cependant, il peut se produire des augmentations de température et donc des dilatations qui dépassent celles pour lesquelles la membrane de dilatation est prévue; il en résulte des surpressions qui peuvent endommager la gaine, par exemple déchirure de la membrane de dilatation, ou le tube, par exemple son éclatement. De tels incidents, outre qu'ils mettent hors de service l'équipement de radiologie, constituent un danger pour les patients et les utilisateurs.However, there may be increases in temperature and therefore expansion which exceeds those for which the expansion membrane is intended; this results in overpressures which can damage the sheath, for example tearing of the expansion membrane, or the tube, for example its bursting. Such incidents, in addition to decommissioning the radiology equipment, pose a danger to patients and users.

Aussi, pour prévenir de tels incidents, les gaines sont équipées de dispositifs d'alarme qui détectent une augmentation trop importante du volume de l'enceinte, c'est-à-dire un déplacement de la membrane de dilatation, et fournissent un signal d'alarme, par exemple à l'aide d'un microcontacteur associé à ladite membrane.D'autres dispositifs d'alarme mesurent la température ou la pression et fournissent un signal d'alarme lorsque les valeurs mesurées dépassent un certain seuil. Ces différents dispositifs d'alarme qui fonctionnent sur une information de dilatation, de température ou de pression, sont souvent utilisés simultanément pour renforcer la probabilité de détection d'un incident et le premier signal d'alarme qui apparaît arrête habituellement le générateur haute tension car il est la source principale de l'échauffement.Also, to prevent such incidents, the ducts are equipped with alarm devices which detect an excessive increase in the volume of the enclosure, that is to say a displacement of the expansion membrane, and provide a signal of alarm, for example using a microswitch associated with said membrane. Other alarm devices measure the temperature or the pressure and provide an alarm signal when the measured values exceed a certain threshold. These various alarm devices which operate on expansion, temperature or pressure information are often used simultaneously to reinforce the probability of detection of an incident and the first alarm signal which appears usually stops the high voltage generator because it is the main source of heating.

Le document US-A-2 290 322 décrit un dispositif de ce type dans lequel un élément sensible à la pression et un interrupteur sont placés à l'intérieur de la gaine de manière telle à couper simultanément l'alimentation électrique du tube et du filament quand la pression dépasse un seuil prédéterminé.Document US-A-2 290 322 describes a device of this type in which a pressure-sensitive element and a switches are placed inside the sheath so as to simultaneously cut the electrical supply to the tube and the filament when the pressure exceeds a predetermined threshold.

Malgré ces dispositifs, des accidents peuvent survenir pour les raisons suivantes. D'abord, tous les dispositifs d'alarme peuvent être en panne ou déréglés mais une telle éventualité est extrêmement rare.Despite these devices, accidents can occur for the following reasons. First, all alarm devices may be broken or out of order, but such a possibility is extremely rare.

Ensuite, le dispositif de coupure du générateur est défaillant et n'a pas fonctionné malgré le signal d'alarme de sorte que la haute tension reste appliquée au tube, un tel cas est aussi très rare. Enfin, un cas moins rare est celui dans lequel certains utilisateurs neutralisent les systèmes de sécurité mis en place par les constructeurs car ils estiment que les seuils de déclenchement sont trop bas pour leur permettre de réaliser toutes les séries d'examen dont ils ont besoin. Un but de la présente invention est donc de réaliser un dispositif de sécurité dont l'action est indépendante du dispositif de coupure du générateur haute tension, ce qui supprime les risques résultant de la défaillance de ce dernier.Then, the generator cut-off device failed and did not work despite the alarm signal so that the high voltage remains applied to the tube, such a case is also very rare. Finally, a less rare case is that in which certain users neutralize the security systems put in place by manufacturers because they consider that the triggering thresholds are too low to allow them to carry out all the series of examinations they need. An object of the present invention is therefore to provide a safety device the action of which is independent of the cut-off device of the high-voltage generator, which eliminates the risks resulting from the failure of the latter.

Un autre but de la présente invention est de réaliser un dispositif de sécurité qui ne peut pas être neutralisé par les utilisateurs.Another object of the present invention is to provide a security device which cannot be deactivated by the users.

L'invention se rapporte à un dispositif de sécurité pour un ensemble radiogène d'un appareil de radiologie qui comprend d'une part, un tube à rayons X enfermé dans une gaine remplie d'un liquide de refroidissement, ledit tube comportant une anode portée à une haute tension par un générateur de tension et une cathode, comportant au moins un filament connecté à un circuit d'alimention électrique, et d'autre part, au moins un dispositif sensible à la température ou à la pression qui est placé à l'intérieur de la gaine, caractérisé en ce que l'interrupteur dudit dispositif interrupteur est connecté en série dans le circuit d'alimentation électrique du filament de cathode de sorte que seule l'alimentation électrique du filament est coupée lorsque la température ou la pression dépasse un seuil prédéterminé et en ce qu'il comprend, en outre, un dispositif de coupure du générateur de tension qui est commandé par un détecteur de courant d'alimentation de la cathode ou de rayonnement X.The invention relates to a safety device for an X-ray assembly of a radiology device which comprises on the one hand, an X-ray tube enclosed in a sheath filled with a coolant, said tube comprising a carried anode at a high voltage by a voltage generator and a cathode, comprising at least one filament connected to an electrical supply circuit, and on the other hand, at least one device sensitive to temperature or to pressure which is placed inside the sheath, characterized in that the switch of said switch device is connected in series in the electrical supply circuit of the cathode filament so that only the electrical supply of the filament is cut off when the temperature or the pressure exceeds a predetermined threshold and in that it further comprises a device for cutting off the voltage generator which is controlled by a cathode supply current or X-ray detector.

D'autres caractéristiques et avantages de la présente invention apparaîtront à la lecture de la description suivante d'un exemple particulier de réalisation, ladite description étant faite en relation avec les dessins joints dans lesquels :

  • la figure 1 est une vue en coupe d'un tube à rayons X équipé de sa gaine de protection et de refroidissement,
  • la figure 2 est un schéma électrique de principe d'un dispositif de sécurité selon l'invention.
Other characteristics and advantages of the present invention will appear on reading the following description of a particular embodiment, said description being made in relation to the accompanying drawings in which:
  • FIG. 1 is a sectional view of an X-ray tube fitted with its protective and cooling sheath,
  • Figure 2 is a block electrical diagram of a safety device according to the invention.

Sur la figure 1, on a représenté un tube 11 à rayons X qui est disposé dans une gaine de refroidissement 12. Le tube 11 à rayons X comporte une enveloppe de verre 13 dans laquelle est réalisé un vide poussé. A l'intérieur de cette enveloppe 13 sont disposées une cathode émissive 14 et une anode 15 qui, dans le cas particulier, est tournante. L'anode 15 est montée à l'extrémité d'un rotor 16 qui coopère avec un stator 17 disposé à l'extérieur de l'enveloppe 13.In Figure 1, there is shown an X-ray tube 11 which is disposed in a cooling sheath 12. The X-ray tube 11 has a glass envelope 13 in which is produced a high vacuum. Inside this envelope 13 are arranged an emissive cathode 14 and an anode 15 which, in the particular case, is rotating. The anode 15 is mounted at the end of a rotor 16 which cooperates with a stator 17 placed outside the casing 13.

La gaine de refroidissement 12 est par exemple réalisée par l'assemblage étanche de quatre parties référencées 18,19,20 et 21. La partie 18, sensiblement centrale, porte la fenêtre de sortie 22 du rayonnement X. Les parties extrêmes 20 et 21 sont fermées à leurs extrémités et portent l'un un orifice d'entrée 23 du liquide de refroidissement et l'autre un orifice de sortie 24 de ce liquide. Les parties 18 et 20 sont reliées par l'intermédiaire de la partie 19.The cooling sheath 12 is for example made by the tight assembly of four parts referenced 18,19,20 and 21. Part 18, which is substantially central, carries the exit window 22 for X-ray radiation. The end parts 20 and 21 are closed at their ends and bear one one inlet port 23 for the coolant and the other an outlet port 24 for this liquid. Parts 18 and 20 are connected through part 19.

Le fluide de refroidissement circule dans l'espace 25 entre l'enveloppe 13 et les parois internes de la gaine 12 et est donc en contact avec l'enveloppe de verre 13 de manière à la refroidir.The cooling fluid circulates in the space 25 between the envelope 13 and the internal walls of the sheath 12 and is therefore in contact with the glass envelope 13 so as to cool it.

Les câbles d'alimentation électrique du tube à rayons X pénètrent dans la gaine 12 par l'orifice 29 pour la cathode 14 et l'orifice 30 pour l'anode 15. Ces orifices 29 et 30 sont équipés de plots isolants 31 et 32 de forme cylindrique qui sont montés de manière étanche. Ces plots se terminent à l'intérieur de la gaine par des bornes électriques 26,27 et 28 pour le plot 31 et 33, 34 35 et 48 pour le plot 32. Du côté extérieur à la gaine 25, ces bornes électriques sont connectées aux conducteurs de chaque câble d'alimentation électrique. A l'intérieur de la gaine 25, les bornes électriques 26, 27 et 28 sont connectées à la cathode 14 composée de deux filaments 39 et 40 par trois conducteurs électriques 36, 37 et 38. De manière similaire, la borne électrique 48 est connectée de manière à porter l'anode tournante 15 à une haute tension positive par rapport à la cathode, cette dernière étant à une tension négative. Par ailleurs, les bornes électriques 33, 34 et 35 sont connectées au stator 17 du moteur.The electric power cables of the X-ray tube penetrate into the sheath 12 through the orifice 29 for the cathode 14 and the orifice 30 for the anode 15. These orifices 29 and 30 are fitted with insulating pads 31 and 32 of cylindrical shape which are tightly mounted. These studs end inside the sheath by electrical terminals 26, 27 and 28 for the stud 31 and 33, 34 35 and 48 for the stud 32. On the outside of the sheath 25, these electrical terminals are connected to the conductors of each power supply cable. Inside the sheath 25, the electrical terminals 26, 27 and 28 are connected to the cathode 14 composed of two filaments 39 and 40 by three electrical conductors 36, 37 and 38. Similarly, the electrical terminal 48 is connected so as to bring the rotating anode 15 to a high positive voltage with respect to the cathode, the latter being at a negative voltage. Furthermore, the electrical terminals 33, 34 and 35 are connected to the stator 17 of the motor.

Le dispositif de sécurité selon l'invention est constitué principalement d'un thermostat et/ou d'un pressostat qui est connecté en série dans le circuit d'alimentation électrique du ou des filaments de cathode et qui est disposé dans le liquide de refroidissement de l'enceinte de la gaine.The safety device according to the invention mainly consists of a thermostat and / or a pressure switch which is connected in series in the circuit electric supply of the cathode filament (s) and which is placed in the coolant of the sheath enclosure.

La figure 2 représente de manière très schématique les éléments principaux du tube à rayons X de la figure 1, éléments qui portent alors les mêmes références sur les deux figures. On a également représenté sur cette figure 2, le schéma électrique d'alimentation de la cathode 14. C'est ainsi que la cathode comporte deux filaments 39 et 40 dont le point commun est connecté au conducteur 37 tandis que les extrémités sont connectées aux conducteurs 36 et 38. Comme il est bien connu, chaque filament sert à créer sur l'anode 15 un foyer source de rayons X qui a des caractéristiques particulières.FIG. 2 very schematically represents the main elements of the X-ray tube of FIG. 1, elements which then bear the same references in the two figures. Also shown in this figure 2, the electrical diagram for supplying the cathode 14. Thus the cathode has two filaments 39 and 40 whose common point is connected to the conductor 37 while the ends are connected to the conductors 36 and 38. As is well known, each filament is used to create on the anode 15 a source of X-ray sources which has particular characteristics.

Côté extérieur à la gaine, les bornes électriques 26,27 et 28, d'une part et 33,34 35 et 48 d'autre part, sont connectées respectivement à un dispositif d'alimentation 41 par l'intermédiaire de conducteurs 26',27' et 28' pour le câble électrique de cathode et 33',34' 35' et 48' pour le câble électrique d'anode.On the outside of the sheath, the electrical terminals 26, 27 and 28, on the one hand and 33, 34 and 48 and 48, on the other hand, are respectively connected to a supply device 41 by means of conductors 26 ′, 27 'and 28' for the cathode electrical cable and 33 ', 34' 35 'and 48' for the anode electrical cable.

Selon l'invention, le thermostat ou le pressostat est connecté en série dans le conducteur commun 37 et est référencé 42. Du point de vue électrique, c'est un interrupteur 43 qui est normalement fermé et qui s'ouvre lorsque la température et/ou la pression dépasse un certain seuil. Du point de vue mécanique, il est disposé dans la gaine et porté soit par le plot 31, soit par le culot de la cathode.According to the invention, the thermostat or the pressure switch is connected in series in the common conductor 37 and is referenced 42. From the electrical point of view, it is a switch 43 which is normally closed and which opens when the temperature and / or the pressure exceeds a certain threshold. From the mechanical point of view, it is disposed in the sheath and carried either by the stud 31, or by the base of the cathode.

Dans l'exemple de la figure 2, le dispositif de sécurité ne comporte qu'un seul élément, un thermostat ou un pressostat mais on peut connecter un thermostat et un pressostat en série de manière à augmenter la sécurité en cas de défaillance de l'un. Par ailleurs, lorsqu'un seul dispositif est utilisé, il est préférable d'utiliser un pressostat car il peut détecter une surpression du liquide de refroidissement alors qu'un thermostat pourrait ne pas déceler une augmentation de température localisée à un endroit quelconque de la gaine.In the example of Figure 2, the safety device has only one element, a thermostat or a pressure switch but you can connect a thermostat and a pressure switch in series so as to increase safety in case of failure of the a. Furthermore, when only one device is used, it is preferable use a pressure switch because it can detect an overpressure in the coolant whereas a thermostat may not detect a localized temperature increase anywhere in the duct.

Le fonctionnement du dispositif de sécurité selon l'invention est simple : dès que la température et/ou la pression dépasse le seuil de réglage du thermostat et/ou du pressostat, l'interrupteur 43 s'ouvre et le filament 39 ou 40 qui était alimenté ne l'est plus. Il en résulte qu'il n'y a plus d'émission d'électrons, ni de rayons X, cette émission d'électrons étant la source principale de l'échauffement de l'ensemble tube-liquide de refroidissement-gaine.The operation of the safety device according to the invention is simple: as soon as the temperature and / or the pressure exceeds the setting threshold of the thermostat and / or the pressure switch, the switch 43 opens and the filament 39 or 40 which was powered no longer is. As a result, there is no longer any emission of electrons or X-rays, this emission of electrons being the main source of the heating of the tube-coolant-sheath assembly.

Comme l'émission de rayons X est coupée, il n'y a plus lieu de maintenir la haute tension sur la cathode et sur l'anode. Aussi, l'invention prévoit un dispositif de détection de l'absence d'émission d'électrons et de rayons X de manière à couper le générateur haute tension. Ce dispositif de détection peut être constitué par un détecteur du courant de cathode disposé à l'extérieur de la gaine sur la partie basse tension du transformateur de chauffage 44. Sur la figure 2, il a été représenté par un relais 46 qui, en cas de coupure du courant d'alimentation de cathode lors du fonctionnement normal, commande l'arrêt de la haute tension par l'intermédiaire d'un contact 45 placé sur l'arrivée basse tension du transformateur 47 d'alimentation haute tension.As the X-ray emission is cut, there is no longer any need to maintain the high voltage on the cathode and on the anode. Also, the invention provides a device for detecting the absence of emission of electrons and X-rays so as to cut off the high voltage generator. This detection device can be constituted by a cathode current detector arranged outside the sheath on the low voltage part of the heating transformer 44. In FIG. 2, it has been represented by a relay 46 which, in the event of cutting the cathode supply current during normal operation, controls the stopping of the high voltage by means of a contact 45 placed on the low voltage inlet of the transformer 47 high voltage supply.

Bien entendu, au lieu d'un détecteur de courant dans le circuit d'alimentation de la cathode, on peut utiliser un détecteur de rayonnement X disposé sur le trajet du faisceau émis par le tube.Of course, instead of a current detector in the cathode supply circuit, it is possible to use an X-ray detector placed on the path of the beam emitted by the tube.

Le dispositif de sécurité selon l'invention pourrait remplacer les dispositifs de sécurité, extérieurs à la gaine, qui sont actuellement utilisés. Cependant, il est préférable que ce nouveau dispositif de sécurité s'ajoute aux précédents de manière à constituer le dernier maillon du système sécurité au cas où tous les autres auraient été défaillants ou neutralisés. De préférence, les différents seuils de déclenchement des différents dispositifs de sécurité doivent être prévus pour que les dispositifs intérieurs à la gaine, ceux de l'invention, ne déclenchent que pour des valeurs de température et/ou de pression plus élevées que celles des dispositifs extérieurs.The security device according to the invention could replace the safety devices, external to the sheath, which are currently used. However, it is preferable that this new safety device is added to the previous ones so as to constitute the last link of the safety system in case all the others have been faulty or neutralized. Preferably, the different triggering thresholds of the various safety devices must be provided so that the devices internal to the sheath, those of the invention, only trigger for values of temperature and / or pressure higher than those of the devices. exteriors.

Le nouveau dispositif de sécurité qui vient d'être décrit présente les avantages suivants par rapport aux dispositifs existants :

  • il ne coupe pas, dans un premier temps, le générateur haute tension, ce qui évite le risque dû à la défaillance du relais de coupure dudit générateur;
  • sa position à l'intérieur de la gaine le rend inaccessible à l'utilisateur et il ne peut donc pas être neutralisé;
  • il est autonome car il n'a pas besoin d'être alimenté électriquement par un circuit séparé et il coupe lui-même le courant d'alimentation de la cathode.
The new security device which has just been described has the following advantages over existing devices:
  • it does not, at first, cut the high voltage generator, which avoids the risk due to the failure of the cut-off relay of said generator;
  • its position inside the sheath makes it inaccessible to the user and therefore cannot be neutralized;
  • it is autonomous because it does not need to be electrically supplied by a separate circuit and it cuts the cathode supply current itself.

Claims (3)

  1. A safety device for an x-ray installation of a radiological system having, on the one hand, an x-ray tube (11) enclosed in a jacket (25) which is filled with a cooling fluid, said tube (11) comprising an anode (15) to which a high voltage is applied by means of a voltage generator (41) and a cathode (14) having at least one heating wire (39 or 40) connected to an electric supply circuit (41) and, on the other hand, at least one temperature- or pressure-sensitive switching device (42) located in the interior (43) of said jacket (25) characterized by the switch of said switching device being circuited in series in the supply circuit of the cathode heating wire so that only the electrical supply of the heating wire is interrupted when the temperature or the pressure exceeds a predetermined threshold value and further characterized by a device (45) for separating said voltage generator, said device being controlled by a detector for the supply current of the cathode or the x rays.
  2. A safety device according to claim 1 characterized by the detector (46) for the cathode supply current which controls said separating device (45) is located outside of the jacket so that the high voltage is no longer applied to the x-ray tube when the current detector (46) detects an interruption of the cathode supply current under normal operating conditions.
  3. A safety device according to claim 1 characterized by the x-ray detector controlling the separating device (45) is located in the beam path so that the high voltage is no longer applied to the x-ray tube when the x-ray detector detects no x ray under normal operating conditions.
EP90401231A 1989-05-10 1990-05-09 Safety device for X-ray installation Expired - Lifetime EP0397562B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8906095 1989-05-10
FR8906095A FR2646982B1 (en) 1989-05-10 1989-05-10 SECURITY DEVICE FOR RADIOGENIC ASSEMBLY

Publications (2)

Publication Number Publication Date
EP0397562A1 EP0397562A1 (en) 1990-11-14
EP0397562B1 true EP0397562B1 (en) 1994-01-12

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EP90401231A Expired - Lifetime EP0397562B1 (en) 1989-05-10 1990-05-09 Safety device for X-ray installation

Country Status (5)

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US (1) US5008916A (en)
EP (1) EP0397562B1 (en)
JP (1) JPH034499A (en)
DE (1) DE69005896T2 (en)
FR (1) FR2646982B1 (en)

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FR2675630B1 (en) * 1991-04-17 1993-07-16 Gen Electric Cgr ARMOR OF A MOTOR STATOR FOR A ROTATING X-RAY TUBE ANODE.
FR2679762B1 (en) * 1991-07-31 1993-11-05 General Electric Cgr Sa SECURITY DEVICE IN A RADIOLOGY APPARATUS.
DE4401066A1 (en) * 1994-01-15 1995-07-20 Philips Patentverwaltung X-ray tube with a temperature sensor
US6542577B1 (en) * 2000-08-18 2003-04-01 Koninklijke Philips Electronics, N.V. Hermetically sealed stator cord for x-ray tube applications
JP4541536B2 (en) * 2000-12-25 2010-09-08 エスアイアイ・ナノテクノロジー株式会社 Discharge detection circuit.
JP4262042B2 (en) * 2003-10-09 2009-05-13 ジーイー・メディカル・システムズ・グローバル・テクノロジー・カンパニー・エルエルシー Heat generating apparatus, X-ray imaging apparatus, and X-ray apparatus overheating prevention method
JP2005185718A (en) * 2003-12-26 2005-07-14 Ge Medical Systems Global Technology Co Llc Radiation tomography apparatus and imaging method
JP2014107158A (en) * 2012-11-28 2014-06-09 Canon Inc Radiation generator

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JPS5130772B1 (en) * 1970-06-11 1976-09-02
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Also Published As

Publication number Publication date
FR2646982A1 (en) 1990-11-16
FR2646982B1 (en) 1992-02-07
EP0397562A1 (en) 1990-11-14
DE69005896D1 (en) 1994-02-24
DE69005896T2 (en) 1994-07-07
US5008916A (en) 1991-04-16
JPH034499A (en) 1991-01-10

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