EP0397562A1 - Safety device for X-ray installation - Google Patents

Safety device for X-ray installation Download PDF

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Publication number
EP0397562A1
EP0397562A1 EP90401231A EP90401231A EP0397562A1 EP 0397562 A1 EP0397562 A1 EP 0397562A1 EP 90401231 A EP90401231 A EP 90401231A EP 90401231 A EP90401231 A EP 90401231A EP 0397562 A1 EP0397562 A1 EP 0397562A1
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EP
European Patent Office
Prior art keywords
cathode
sheath
safety device
ray
filament
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
EP90401231A
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German (de)
French (fr)
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EP0397562B1 (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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Publication of EP0397562A1 publication Critical patent/EP0397562A1/en
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/26—Measuring, controlling or protecting
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/02—Constructional details
    • H05G1/025—Means for cooling the X-ray tube or the generator
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/02—Constructional details
    • H05G1/04—Mounting the X-ray tube within a closed housing
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/54—Protecting or lifetime prediction

Definitions

  • 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.
  • X-ray tubes for medical diagnosis for example, generally consist of 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.
  • anodic current 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.
  • the rotary anode of the conventional type has the general shape of a disc, having an axis of symmetry around 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.
  • 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 emits only 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 amount of heat to be removed depending on the phase considered, which leads in particular 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 oil contained in the enclosure of the sheath is therefore subjected to temperature rises which have for effect of producing an expansion of the volume of oil and, consequently, an overpressure inside the enclosure of said sheath.
  • the sheath is equipped with a membrane which, as it moves, increases or decreases the volume of the enclosure containing the cooling oil.
  • 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 shutdown 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 an X-ray tube enclosed in a sheath filled with a coolant, said tube comprising an anode brought to a high voltage by a voltage generator and a cathode, comprising at least one filament connected to an electrical supply circuit, characterized in that it comprises at least one device sensitive to temperature or to pressure which is placed inside the sheath and connected in series in the electrical supply circuit of the cathode filament so that the electrical supply of the filament is cut off when the temperature or the pressure exceeds a predetermined threshold.
  • the temperature sensitive device is a thermostat and the pressure sensitive one is a pressure switch.
  • One or the other or both can be used in series in the supply circuit, which increases safety.
  • a device for detecting the supply current and a cut-off device for the voltage generator which is controlled by the current detection device so as to cut the generator.
  • the current detector detects the interruption of the cathode electrical supply.
  • the supply current detection device can be replaced by an X-ray detector emitted by the X-ray tube.
  • FIG. 1 there is shown an X-ray tube 11 which is arranged in a cooling sheath 12.
  • the X-ray tube 11 has a glass envelope 13 in which a high vacuum is produced. 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 watertight 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 supply 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 with 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.
  • 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.
  • 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.
  • each filament serves to create on the anode 15 a source of X-ray sources which has particular characteristics.
  • 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 a thermostat and a pressure switch can be connected in series so as to increase safety in the event 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 placed outside the sheath on the low voltage part of the heating transformer 44.
  • a relay 46 which, in the event 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 supply 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 different safety devices must be provided so that the devices inside the sheath, those of the invention, only trigger for higher values of temperature and / or pressure than those of the devices exteriors.
  • the new security device which has just been described has the following advantages over existing devices: - It does not initially 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.

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

Abstract

The invention relates to X-ray tubes which are arranged inside a sealed cladding (25) filled with a cooling fluid. <??>According to the invention the safety device consists of a thermostat and/or pressure regulator 42 which is connected in series in the power circuit for the filament of the cathode 14. In the case of a cathode with two filaments 39 and 40, the thermostat and/or pressure regulator is connected to the common conductor 37. Thus, should a temperature or pressure threshold be exceeded, power to the filament is cut, and this halts the X-radiation. <??>The invention is applicable to radiology instruments. <IMAGE>

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, generally consist of 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 around 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 emits only 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 amount of heat to be removed depending on the phase considered, which leads in particular 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 rises 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.

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. 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.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. 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 some users neutralize the security systems put in place by manufacturers because they believe that the trigger 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 shutdown 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 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, caractérisé en ce qu'il comprend au moins un dispositif sensible à la température ou à la pression qui est placé à l'intérieur de la gaine et connecté en série dans le circuit d'alimentation électrique du filament de cathode de sorte que l'alimentation électrique du filament est coupée lorsque la température ou la pression dépasse un seuil prédéterminé.The invention relates to a safety device for an X-ray assembly of a radiology device which comprises an X-ray tube enclosed in a sheath filled with a coolant, said tube comprising an anode brought to a high voltage by a voltage generator and a cathode, comprising at least one filament connected to an electrical supply circuit, characterized in that it comprises at least one device sensitive to temperature or to pressure which is placed inside the sheath and connected in series in the electrical supply circuit of the cathode filament so that the electrical supply of the filament is cut off when the temperature or the pressure exceeds a predetermined threshold.

Le dispositif sensible à la température est un thermostat et celui sensible à la pression est un pressostat. On peut utiliser l'un ou l'autre ou les deux connectés en série dans le circuit d'alimentation, ce qui renforce la sécurité.The temperature sensitive device is a thermostat and the pressure sensitive one is a pressure switch. One or the other or both can be used in series in the supply circuit, which increases safety.

En outre, il peut être prévu, à l'extérieur de la gaine, un dispositif de détection du courant d'alimentation et un dispositif de coupure du générateur de tension qui est commandé par le dispositif de détection de courant de manière à couper le générateur de tension lorsque, en fonctionnement normal, le détecteur de courant détecte la coupure de l'alimentation électrique de la cathode.In addition, there may be provided, outside the sheath, a device for detecting the supply current and a cut-off device for the voltage generator which is controlled by the current detection device so as to cut the generator. voltage when, in normal operation, the current detector detects the interruption of the cathode electrical supply.

Le dispositif de détection du courant d'alimentation peut être remplacé par un détecteur du rayonnement X émis par le tube à rayons X.The supply current detection device can be replaced by an X-ray detector emitted by the X-ray tube.

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 exemplary 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 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 arranged in a cooling sheath 12. The X-ray tube 11 has a glass envelope 13 in which a high vacuum is produced. 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 watertight 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 supply 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 with 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 serves 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 side outside 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 in FIG. 2, the safety device has only one element, a thermostat or a pressure switch, but a thermostat and a pressure switch can be connected in series so as to increase safety in the event 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 placed 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 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 supply 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 different safety devices must be provided so that the devices inside the sheath, those of the invention, only trigger for higher values of temperature and / or pressure 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 initially 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 (6)

1.Dispositif de sécurité pour un ensemble radiogène d'un appareil de radiologie qui comprend un tube (11) à rayons X enfermé dans une gaine (25) rempli d'un liquide de refroidissement, ledit tube (11) comportant une anode (15) et une cathode (14) connectées à un générateur de tension (41), ladite cathode (14) comportant au moins un filament (39 ou 40) connecté à un circuit alimentation électrique (41) caractérisé en ce qu'il comprend au moins un dispositif (42) sensible à la température ou à la pression qui est placé à l'intérieur de la gaine (25) et un interrupteur (43), également placé à l'intérieur de la gaine (25), qui est connecté en série dans le circuit d'alimentation du filament de cathode et qui est commandé par ledit dispositif (42) de manière que l'alimentation électrique du filament (39,40) soit coupée lorsque la température ou la pression dépasse un seuil prédéterminé.1.Safety device for an X-ray assembly of an X-ray device which comprises an X-ray tube (11) enclosed in a sheath (25) filled with a coolant, said tube (11) comprising an anode (15 ) and a cathode (14) connected to a voltage generator (41), said cathode (14) comprising at least one filament (39 or 40) connected to an electrical supply circuit (41) characterized in that it comprises at least a device (42) sensitive to temperature or pressure which is placed inside the sheath (25) and a switch (43), also placed inside the sheath (25), which is connected in series in the cathode filament supply circuit and which is controlled by said device (42) so that the electrical supply to the filament (39,40) is cut off when the temperature or pressure exceeds a predetermined threshold. 2. Dispositif de sécurité selon la revendication 1, caractérisé en ce que le dispositif (42) sensible à la température est un thermostat.2. Safety device according to claim 1, characterized in that the device (42) sensitive to temperature is a thermostat. 3. Dispositif de sécurité selon la revendication 1, caractérisé en ce que le dispositif (42) sensible à la pression est un pressostat.3. Safety device according to claim 1, characterized in that the device (42) sensitive to pressure is a pressure switch. 4. Dispositif de sécurité selon la revendication 2 ou 3, caractérisé en ce qu'un thermostat et un pressostat sont connectés en série dans le circuit d'alimentation du filament de la cathode.4. Safety device according to claim 2 or 3, characterized in that a thermostat and a pressure switch are connected in series in the filament supply circuit of the cathode. 5. Dispositif de sécurité selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il comprend, en outre, un détecteur (46) de courant d'alimentation de la cathode disposé à l'extérieur de la gaine (25) et un dispositif de coupure (45) du générateur de tension qui est commandé par ledit détecteur de courant (46) de manière que la haute tension ne soit plus appliquée au tube à rayons X lorsque le détecteur de courant (46) détecte, en fonctionnement normal, la coupure du courant d'alimentation de la cathode.5. Safety device according to any one of the preceding claims, characterized in that it further comprises a current detector (46) supplying the cathode disposed outside the sheath (25) and a cut-off device (45) of the voltage generator which is controlled by said current detector (46) so that the high voltage is no longer applied to the x-ray tube when the current detector (46) detects, in normal operation, the interruption of the cathode supply current. 6. Dispositif de sécurité selon l'une quelconque des revendications précédentes 1 à 4, caractérisé en ce qu'il comprend, en outre, un détecteur de rayonnement X disposé sur le trajet du faisceau et un dispositif de coupure du générateur de tension qui est commandé par ledit détecteur de rayonnement de manière que la haute tension ne soit plus appliquée au tube à rayons X lorsque le détecteur de rayonnement détecte, en fonctionnement normal, l'absence de rayonnement X.6. Safety device according to any one of the preceding claims 1 to 4, characterized in that it further comprises an X-ray detector arranged in the path of the beam and a device for cutting off the voltage generator which is controlled by said radiation detector so that the high voltage is no longer applied to the X-ray tube when the radiation detector detects, in normal operation, the absence of X-radiation.
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
FR8906095A FR2646982B1 (en) 1989-05-10 1989-05-10 SECURITY DEVICE FOR RADIOGENIC ASSEMBLY
FR8906095 1989-05-10

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

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EP (1) EP0397562B1 (en)
JP (1) JPH034499A (en)
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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.
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Also Published As

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DE69005896T2 (en) 1994-07-07
US5008916A (en) 1991-04-16
JPH034499A (en) 1991-01-10
FR2646982B1 (en) 1992-02-07
EP0397562B1 (en) 1994-01-12
FR2646982A1 (en) 1990-11-16
DE69005896D1 (en) 1994-02-24

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