EP0540392B1 - Gaine de tube intensificateur d'image radiologique - Google Patents

Gaine de tube intensificateur d'image radiologique Download PDF

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Publication number
EP0540392B1
EP0540392B1 EP92402831A EP92402831A EP0540392B1 EP 0540392 B1 EP0540392 B1 EP 0540392B1 EP 92402831 A EP92402831 A EP 92402831A EP 92402831 A EP92402831 A EP 92402831A EP 0540392 B1 EP0540392 B1 EP 0540392B1
Authority
EP
European Patent Office
Prior art keywords
casing
sheath
tube
shield
housing according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP92402831A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0540392A1 (fr
Inventor
Maurice Thomson-Csf Verat
Serge Thomson-Csf Cozzi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thales Electron Devices SA
Original Assignee
Thomson Tubes Electroniques
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Thomson Tubes Electroniques filed Critical Thomson Tubes Electroniques
Publication of EP0540392A1 publication Critical patent/EP0540392A1/fr
Application granted granted Critical
Publication of EP0540392B1 publication Critical patent/EP0540392B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/86—Vessels; Containers; Vacuum locks
    • H01J29/867—Means associated with the outside of the vessel for shielding, e.g. magnetic shields
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2231/00—Cathode ray tubes or electron beam tubes
    • H01J2231/50—Imaging and conversion tubes
    • H01J2231/50005—Imaging and conversion tubes characterised by form of illumination
    • H01J2231/5001—Photons
    • H01J2231/50031—High energy photons
    • H01J2231/50036—X-rays

Definitions

  • the invention relates to the sheaths of radiological image intensifier tubes and the means used in these sheaths in particular to provide protection against X-radiation.
  • the radiological image intensifier tubes are vacuum tubes comprising an input screen towards the front of the tube, an electronic optical system, and an image observation screen. visible on the back of the tube.
  • FIG. 1 schematically shows such an IIR tube.
  • the tube comprises a glass vacuum enclosure 2, one end of which at the front of the tube, is closed by an inlet window 3 exposed to X-ray photon radiation.
  • the second end of the enclosure 2 forming the rear of the tube is closed by an outlet window 4 transparent to light.
  • the X-rays are converted into light rays by a scintillator screen 5.
  • the light rays excite a photocathode 6 which in response emits electrons.
  • These electrons are accelerated towards the exit window 4 using different electrodes 7 arranged along a longitudinal axis 9 of the tube, and which form the electronic optical system.
  • the exit window 4 carries a cathodoluminescent screen 10, made of phosphors for example.
  • the impact of the electrons on the cathodoluminescent screen 10 makes it possible to reconstruct an image formed at the start on the photocathode 6.
  • the wall of a conventional sheath 15 for an IIR tube generally comprises several superposed layers 16, 17, 18.
  • the outermost layer 16 forms an envelope 16 which is the mechanical framework of the sheath 15. It is an envelope which may be of the type for example; molded metal alloy; either pushed back or stamped; or mechanically welded from metal sheets.
  • the outer layer 16 or envelope 16 provides mechanical protection of the vacuum enclosure, and particularly in its rear part 13 located towards the outlet window 4 of the tube, it provides the attachment interface.
  • the image produced by the cathodoluminescent screen 10 is visible outside the sheath thanks to an opening 14 made in the rear part 13.
  • This inner layer or shield 17 is made of a material having a high magnetic permeability, such as, for example, soft iron, or an iron-based alloy such as example the "permalloy” (iron-nickel alloy), or even metal, etc ...
  • the inner layer 17 forming a shield against magnetic fields is produced from sheets of these materials with high magnetic permeability.
  • a second inner layer 18, disposed between the enclosure 2 of the tube and the first inner layer 17, constitutes a screen whose function is to absorb X-rays; the aim with the aid of this screen 18 is to attenuate the X-ray radiation which leaves the sheath 15.
  • this second inner layer 18 are also generally available in the form of sheets, so that the production of this second inner layer or screen 18 (but also of the first inner layer 17) calls on the techniques of boilermaking: partial stamping, embossing, rolling, mechanical welding. These techniques result in long and costly operations, which also result in high geometric tolerances.
  • the second inner layer or screen 18 it is common to use materials with a high atomic number, and more particularly lead, which has the advantage of being of low cost and of strongly absorbing X-radiation. .
  • lead is a difficult material to process because of its great malleability or ductility.
  • the work of lead is regulated and the personnel who perform this work are subject to medical surveillance constraints.
  • the purpose of absorbing X-rays is to attenuate the X-rays leaving the sheath, up to a value compatible with regulations.
  • the intensities of this incident X-ray are not equal at all points of the sheath 15, the absorption of the radiation does not necessarily have to be equal at all these points, and it suffices to confer on the wall of the sheath in these different points, with an appropriate absorption coefficient to obtain the desired attenuation.
  • the thickness of the screen or absorbent layer 18 of the Xs is calculated to reduce to the regulatory value the highest incident X-ray level existing in each zone.
  • the thickness of the layer or screen 18 is chosen for the attenuation of the X-radiation having the highest intensity.
  • the quantity of material constituting the screen 18 is superabundant in many points of the latter, which leads to increases in weight and cost.
  • zones a , b , c , d , e of the screen 18 it is common to confer on the different zones a , b , c , d , e of the screen 18, if it is made up of lead sheets, thicknesses respectively of about 1.7 mm, 1, 2 mm, 2.3 mm, 1.2 mm and 2.7 mm, while for zone b for example the major part of this area could be only 0.6mm thick.
  • the subject of the invention is an IIR tube sheath, the design of which makes it possible to avoid the above-mentioned drawbacks.
  • the sheath according to the invention makes it possible to provide the various necessary protections, while having a lower weight than in the prior art, as well as greater ease of manufacture and therefore lower cost.
  • a sheath of a radiological image intensifier tube comprising an envelope, an X-ray absorbing screen, a shielding against external magnetic fields, is characterized in that the envelope is at least partially consisting of a thermoplastic resin loaded with a powder of an X-ray absorbing material, so that said screen is at least partially constituted by the envelope.
  • material absorbing X ⁇ radiation we mean defining a material (used pure or alloyed or else a compound of this material) whose atomic number is sufficiently high (for example equal to or greater than 70) to ensure significant absorption X-rays passing through it, such as lead or oxide, lead for example. Such materials are commonly used for protection against X-rays, in particular in the field of radiology.
  • One of the advantages of such an arrangement is not only that it makes it possible to remove the layer made of lead sheets, or of another material with a high atomic number, but also that the envelope constitutes a particularly advantageous means for support and hang shielding.
  • FIG. 2 shows a sheath 20 according to the invention, containing an image intensifier tube.
  • This image intensifier tube being for example of a type similar to that shown in FIG. 1, it is represented in FIG. 2 only by its enclosure 2.
  • the sheath 20 has a general shape similar to that of FIG. 1, that is to say, it has a large opening 21 called the inlet opening located on the side of the inlet window 3 of the tube, and an outlet opening 22 on the side of the outlet window 4.
  • the sheath 20 comprises a wall 25 forming an envelope, made of a composite material allowing this wall to fulfill both the function of mechanical framework and screen absorbing X-radiation.
  • composite material may consist of an injectable thermoplastic material loaded with a material (in powder form) with a high atomic number in order to absorb the X-ray in a significant manner, as has already been explained in the preamble.
  • thermoplastic material or base material can be for example: ABS (acrylonitrile-butadiene-styrene) such as for example the product called "RONFALIN” produced by DSM (Company in Germany, producer of pastic materials); or even high density polypropylene; these two products have been tested with satisfaction, but there are many others which can be used.
  • ABS acrylonitrile-butadiene-styrene
  • RONFALIN product produced by DSM (Company in Germany, producer of pastic materials)
  • high density polypropylene these two products have been tested with satisfaction, but there are many others which can be used.
  • the material forming the charge that is to say the material (in the form of powder) absorbing the X-ray
  • a lead oxide PbO more particularly a litharge the others lead oxides being less advantageous because their lead content is lower.
  • other materials or other heavy metal oxides can also be used to absorb X-radiation as explained above, since these materials are in the form of powder to charge the base material.
  • the above-mentioned lead oxide (litharge) was used with a particle size of less than 45 ⁇ m, for charging "RONFALIN” produced by DSM with a charge rate of the order of 35% by volume.
  • the 35% loading rate can be considered to be substantially a maximum above which problems arise in the injection molding technique.
  • JP-A-63 293 500 describes an X-ray absorbing screen made of a plastic material charged with a powder of lead oxide.
  • the material loaded with heavy material, intended to constitute the wall 25 of the sheath 15 can be used by injection molding techniques which in themselves are conventional.
  • injection molding techniques for the production of a sheath 20, an advantage of injection molding techniques is that they make it possible to obtain relatively simple parts having complex geometric shapes.
  • the cost of the parts obtained by molding is low while having good reproducibility of these parts, and the tolerances on the dimensions are lower than in the case of the sheaths produced according to the techniques of the prior art.
  • Another important advantage which the realization by molding of the wall 25 brings, is that it makes it possible to confer, at all points on this wall, the thickness E1, E2, E3 strictly necessary to absorb the X-ray radiation existing at each of these points. , resulting in a reduction in size and weight as well as a saving in material.
  • zone b has a greater thickness E1 of the order of 5 mm towards the front 21, and a smaller thickness E2 of the order of 2.5 mm towards the rear 13.
  • the sheath 15 comprises a layer 24 of a material with high magnetic permeability forming a shielding 24 against external magnetic fields, and at least partially surrounding the enclosure 2 of the tube.
  • the shield 24 is disposed against the wall 25 inside the sheath 20.
  • the shield 24 can be produced from sheets of a material with high magnetic permeability, and these sheets can be secured to the wall 25 by gluing for example. But this can be done in a much simpler way, by inserting these sheets in the mold in order to constitute the layer 24 before injecting the material serving to constitute the wall 25.
  • the sheets can line the bottom of the mold, before the injection of material, and they are made integral with the wall 25 by adhesion of the material on the layer 24 forming a shield, during the cooling of this material. It is also possible according to a technique in itself known to provide hooking elements (not shown) in the shielding layer 24.
  • a sheath 20 produced in accordance with the invention makes it possible to use the technique of "inserts".
  • This technique consists in placing objects in the mold before injecting the material to be molded, so as to at least partially drown them in this material and thus making them mechanically integral with the solidified material. It is thus possible, for example, to constitute nuts 30, 31 "in insert” (embedded in the wall 25) and / or studs not shown, in order to ensure the various fastenings.
  • nuts 30 "insert” are arranged in a front portion 27 of the sheath 20 (located on the side of the inlet opening 21) to allow the fixing the tube 1 to the equipment (not shown) with which it is associated; and on the other hand other screens 31 in “insert” are arranged on a bottom part 28 (in which the outlet opening 22 is made), to allow the attachment of accessories (not shown).
  • the shield 24 in addition to its shielding function, reinforces the mechanical rigidity of the wall 25, and in the case of particularly heavy loads to be fixed, the shield 24 avoids having to give the wall 25, locally, a thickness larger than that which is strictly necessary to absorb the X-radiation.
  • the wall 25 of thermoplastic material even when charged, constitutes an electrical insulator which can locally accumulate electrical charges, all the more so since very often the outlet window 4 of the tube comprises metal parts brought to the potential of the high voltage supply of the tube.
  • the shield 24 being an electrically conductive surface, it can in this case be brought to a reference potential, ground for example, so as to constitute a screen on an electrical plane, between the outlet window 4 and the envelope 25 of the sheath 20.
  • FIG. 3 illustrates another embodiment which differs from that shown in FIG. 2 in that the shield 24 is secured to the wall 25 outside the sheath 20, the variations in thickness E1, E2 having an impact on inside the sheath 20.
  • One of the advantage of this arrangement is that it makes it possible to achieve total protection of people and equipment against electrical voltages and currents, if the shield is brought to the reference potential such as ground.
  • the shield 24 can be constituted in the same way as in the case of the example of FIG. 2, from sheets (not shown) of a metallic material of high magnetic permeability; these sheets can in this case also be placed as an "insert" in the mold, in order to be outside the wall 25, that is to say outside the sheath 20.
  • the nuts 30, 31 can be placed as an "insert” as in the example in FIG. 2, passing for example through the shielding 24.
  • the front part 21 is shown attached to the wall 25. It is indeed necessary to separate the part before 21 forming a cover, of the body, that is to say of the rest of the sheath 20 for introducing the IIR tube into the sheath.
  • the assembly of the front part 21 with the body of the sheath is shown in the form of the adhesive joint 35, but of course other means can be used for this purpose, such as for example, screwing, snap-fastening, etc. ...

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
EP92402831A 1991-10-31 1992-10-16 Gaine de tube intensificateur d'image radiologique Expired - Lifetime EP0540392B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9113488A FR2683387A1 (fr) 1991-10-31 1991-10-31 Gaine de tube intensificateur d'image radiologique.
FR9113488 1991-10-31

Publications (2)

Publication Number Publication Date
EP0540392A1 EP0540392A1 (fr) 1993-05-05
EP0540392B1 true EP0540392B1 (fr) 1995-05-10

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP92402831A Expired - Lifetime EP0540392B1 (fr) 1991-10-31 1992-10-16 Gaine de tube intensificateur d'image radiologique

Country Status (5)

Country Link
US (1) US5304792A (ja)
EP (1) EP0540392B1 (ja)
JP (1) JP3639866B2 (ja)
DE (1) DE69202437T2 (ja)
FR (1) FR2683387A1 (ja)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19742548C2 (de) * 1997-09-26 1999-10-07 Otten Ernst Wilhelm Magneteinrichtung für Tansport und Aufbewahrung kernspinpolarisierter Gase und Verfahren zur Entnahme dieser Gase
DE19818442A1 (de) * 1998-04-24 1999-07-15 Siemens Ag Gehäuse eines Röntgenbildverstärkers
US8022116B2 (en) * 2003-07-18 2011-09-20 Advanced Shielding Components, Llc Lightweight rigid structural compositions with integral radiation shielding including lead-free structural compositions
US11659645B2 (en) 2021-06-01 2023-05-23 Moxtek, Inc. Monolithic x-ray source housing

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL178286C (nl) * 1977-03-03 1986-02-17 Philips Nv Beeldversterkerbuis in een omhulling met verend materiaal.
JPS5620264U (ja) * 1979-07-24 1981-02-23
JPS63293500A (ja) * 1987-05-27 1988-11-30 Mitsubishi Cable Ind Ltd 医療用ｘ線遮蔽ブロック
JPH03272553A (ja) * 1990-02-27 1991-12-04 Toshiba Corp Ｘ線イメージ管装置
FR2666448B1 (fr) * 1990-09-04 1992-10-16 Thomson Tubes Electroniques Tube intensificateur d'image a isolation electrique optimisee.

Also Published As

Publication number Publication date
DE69202437D1 (de) 1995-06-14
US5304792A (en) 1994-04-19
FR2683387A1 (fr) 1993-05-07
JPH0628989A (ja) 1994-02-04
EP0540392A1 (fr) 1993-05-05
DE69202437T2 (de) 1995-09-14
JP3639866B2 (ja) 2005-04-20

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