EP0460421A1 - Tube à rayons X - Google Patents

Tube à rayons X Download PDF

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Publication number
EP0460421A1
EP0460421A1 EP91107516A EP91107516A EP0460421A1 EP 0460421 A1 EP0460421 A1 EP 0460421A1 EP 91107516 A EP91107516 A EP 91107516A EP 91107516 A EP91107516 A EP 91107516A EP 0460421 A1 EP0460421 A1 EP 0460421A1
Authority
EP
European Patent Office
Prior art keywords
ray tube
wall
anode
electron beam
potential
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.)
Withdrawn
Application number
EP91107516A
Other languages
German (de)
English (en)
Inventor
Herbert Dipl.-Ing. Bittl (Fh)
Rudolf Dipl.-Phys. Friedel
Klaus Dr. Rer. Nat. Haberrecker
Ernst Dipl.-Ing. Neumeier (Fh)
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.)
Siemens AG
Original Assignee
Siemens AG
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 Siemens AG filed Critical Siemens AG
Publication of EP0460421A1 publication Critical patent/EP0460421A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/24—Tubes wherein the point of impact of the cathode ray on the anode or anticathode is movable relative to the surface thereof
    • H01J35/30—Tubes wherein the point of impact of the cathode ray on the anode or anticathode is movable relative to the surface thereof by deflection of the cathode ray
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/16—Vessels; Containers; Shields associated therewith
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/16—Vessels
    • H01J2235/165—Shielding arrangements
    • H01J2235/168—Shielding arrangements against charged particles

Definitions

  • the invention relates to an X-ray tube with a cathode and an anode, which are arranged in an evacuated housing surrounded by a cooling medium.
  • X-ray tubes of the type mentioned at the outset it is also often desirable to be able to influence the position of the focal spot on the anode.
  • a deflection coil which allows the electron beam to be deflected in accordance with a current flowing through the deflection coil. Since the presence of the deflection coil inside the evacuated housing is generally undesirable - this can have adverse consequences for the quality of the vacuum present in the housing - the deflection coil is usually arranged outside the evacuated housing, with the result that it is very far from the electron beam. Relatively large electrical powers are therefore required to deflect the electron beam. In addition, the deflection coil is very large and accordingly expensive.
  • the invention has for its object to provide an X-ray tube of the type mentioned in such a way that a low electrical power is sufficient to deflect the electron beam by means of a deflection coil and the deflection coil is small and inexpensive.
  • at least the prerequisites should be met for a significant reduction in extrafocal radiation to be achieved without components of the X-ray tube being subjected to increased thermal stress and thereby possibly suffering damage.
  • this object is achieved according to a first solution principle by an X-ray tube with a cathode and an anode, which are arranged in an evacuated housing surrounded by a cooling medium, in which the electron beam emanating from the cathode on its way to the anode runs in a shaft-like wall of the evacuated housing, which is surrounded by a deflection coil provided for deflecting the electron beam.
  • the deflection coil is thus close to the electron beam to be deflected, with the result that the power required to deflect the electron beam is low and the deflection coil is small and inexpensive.
  • Particularly favorable conditions result if the cross section of the shaft-like wall according to a particularly preferred embodiment of the invention does not significantly exceed the size required for unhindered passage of the electron beam.
  • the shaft-like wall is at a potential that is more positive than the cathode potential.
  • the shaft-like wall collects the electrons scattered back from the anode and thus causes a reduction in the extrafocal radiation.
  • the shaft-like design of the wall, the cross section of which forms an aperture so to speak, the number of backscattered electrons that enter the aperture and rush back to the anode is only small, since a significant proportion of those that have entered the aperture Electrons are captured by the shaft-like wall. It is advantageous that no additional components are required to implement the aperture function. If, according to an advantageous variant of the invention, it is provided that the shaft-like wall is at least partially adjacent to the cooling medium, it is ensured that the shaft-like wall does not heat up excessively under the bombardment of the electrons. Increased thermal stresses are avoided.
  • Another expedient variant of the invention provides that the deflection coil is at least partially surrounded by the cooling medium. This ensures that the power loss of the coil is easily dissipated.
  • the shaft-like wall is connected to a wall of the evacuated housing which has an aperture, is at a potential which is more positive than the cathode potential and at least partially adjoins the cooling medium.
  • the shaft-like wall e.g. because it is at an unsuitable potential or is designed as an insulator, is not able to capture the electrons to an extent sufficient for a desired reduction in the extrafocal radiation, but nevertheless reduce the extrafocal radiation to the required extent, since the backscattered electrons of the wall having the aperture opening are captured. Overheating of this wall cannot occur since it is at least partially adjacent to the cooling medium.
  • the above object is achieved according to a second solution principle by an X-ray tube with a cathode and an anode, which are arranged in an evacuated housing surrounded by a cooling medium, in which the electron beam emanating from the cathode on its way to the anode passes through an aperture opening delimited by at least one wall of the evacuated housing at least partially adjacent to the cooling medium, the wall having the aperture opening being at a potential which is more positive than the cathode potential, and wherein a deflection coil for deflecting the electron beam is arranged in the region of the aperture opening which is at least partially surrounded by the cooling medium.
  • the aperture opening can be delimited by a plurality of walls of the housing, which are then preferably all at the potential mentioned and at least partially adjoin the cooling medium. Due to the fact that the deflection coil is arranged in the area of the aperture and is at least partially surrounded by the cooling medium, it is achieved that the deflection coil is very close to the electron beam and thus only a low power is required to deflect the electron beam. On the other hand, it is achieved that the power loss of the coil is easily transferred to the cooling medium. In addition, since the coil is close to the electron beam, it is small and correspondingly inexpensive.
  • the electron beam on its way to the anode runs in a shaft-shaped wall of the evacuated housing which is surrounded by the deflection coil.
  • the deflection coil can be brought particularly close to the electron beam, with the advantages that the power required for deflection is particularly low and the deflection coil is particularly compact.
  • a particularly advantageous embodiment of the invention provides that the shaft-shaped wall limits the aperture opening. The result of this is that the number of backscattered electrons that enter the aperture opening and rush out of it back onto the anode is reduced, since a significant proportion of the electrons entering the aperture opening are captured by the shaft-like wall.
  • the reduction in extrafocal radiation is greatest when, according to one embodiment of the invention, it is provided that the dimensions of the aperture opening do not substantially exceed the dimensions required for unimpeded passage of the electron beam, since then the proportion of the wall provided with the aperture opening Housing falling backscattered electrons is greatest.
  • the wall having the aperture opening is at anode potential.
  • This measure is provided that that the dimensions of the aperture are not larger than necessary, the formation of extrafocal radiation is almost completely avoided, since practically all backscattered electrons are captured by the wall of the housing acting as an aperture and only a negligible proportion of the electrons can fall back onto the anode.
  • no special measures are advantageously required to ensure that the wall provided with the aperture opening is at anode potential.
  • the isolator provided between the cathode and the housing must isolate the full tube voltage.
  • the deflection coil is arranged in the region of the aperture and is at least partially surrounded by the cooling medium. In this way, on the one hand, it is achieved that the deflection coil can be very close to the electron beam and thus only a low power is required to deflect the electron beam. On the other hand, it is achieved that the power loss of the coil can be easily transferred to the cooling medium.
  • FIG. 1 to 3 each show an X-ray tube according to the invention in a schematic representation in longitudinal section.
  • the X-ray tube according to FIG. 1 has a fixed cathode 1 and a rotating anode, designated as a whole by 2, which in one Evacuated housing 3 are arranged, which in turn is accommodated in a protective housing 4 filled with an electrically insulating, liquid cooling medium, for example insulating oil.
  • the rotating anode 2 is rotatably supported in the housing 3 by means of a shaft 5 and two roller bearings 6, 7.
  • the rotationally symmetrical rotary anode 2 the central axis M of which coincides with that of the shaft 5, has a frustoconical section 8 which is provided with a layer 9 of a tungsten-rhenium alloy onto which an electron beam 10 emanating from the cathode 1 is generated of x-rays.
  • the corresponding useful beam emerges through beam exit windows 11 and 12 provided in the housing 3 and the protective housing 4 and aligned with one another.
  • an electric motor designated overall as 13 and designed as a squirrel-cage motor, which has a stator 15 placed on the housing 3 and a rotor 16 located inside the housing 3 and connected to the shaft 5 in a rotationally fixed manner.
  • the housing 3 carrying earth potential 17 has two approximately plate-shaped housing parts 18a and 18b, which are connected vacuum-tight to a tubular housing part 19 at the ends thereof, and a shaft-shaped housing part 18c, which is connected vacuum-tight to the housing part 18a. At least the housing parts 18a and 18c are made of metallic material.
  • the cathode 1 is attached to the shaft-shaped housing part 18c by means of an insulator 20, which is connected to the housing part 18c in a vacuum-tight manner. The cathode 1 is thus, so to speak, in a special chamber of the housing 3, which is connected to it via the shaft-shaped housing part 18c.
  • the housing part 18a is provided in the region of the focal spot F with an indentation 21 projecting into the housing and thus approximately in shape in the region of the focal spot F that of the housing part 18a facing surface of the rotating anode 2 adapted.
  • the housing part 18a has a central bore into which a cup-shaped insulator 22 is inserted in a vacuum-tight manner.
  • the outer ring of the roller bearing 6 is received in the depression of the insulator 22 located within the housing 3.
  • the housing part 18b also has a central bore aligned with the bore of the housing part 18a, into which a further tubular housing part 23 is inserted in a vacuum-tight manner, which accommodates the rotor 16 in its interior and the stator 15 is placed on the outer lateral surface thereof.
  • an insulator 24 is inserted in a vacuum-tight manner in the housing part 23, which is provided on its end face located in the interior of the housing 3 with an annular projection which serves to receive the outer ring of the roller bearing 7.
  • the supply of the positive high voltage + U for the rotating anode 2 takes place by means of a contact 26 which resiliently rests on the shaft 5 and is accommodated in a vacuum-tight manner in the insulator 22 in a manner which is not known and is known per se.
  • the negative high voltage -U is present at one connection of the cathode 1.
  • the heating voltage U H lies between the two connections of the cathode 1.
  • the leads leading to the cathode 1, the pin 26, the housing 3 and the stator 15 are connected to a voltage supply, not shown, located outside the protective housing 4, which is known per se and which supplies the voltages required to operate the X-ray tube. From the above, it is clear that the X-ray tube according to FIG. 1 is designed with two poles.
  • Fig. 1 From Fig. 1 it can be seen that the electron beam 10 emanating from the cathode 1 on its way to the rotating anode 2 passes through the shaft-shaped housing part 18c and through an opening aligned with the bore of the shaft-shaped housing part 18c, which in the housing part 18a in the region of the Indentation 21 is attached.
  • the housing parts 18a and 18c thus fulfill the function of an aperture serving to reduce the extrafocal radiation. Since the housing parts 18a and 18c delimiting or having the diaphragm opening 27 are in direct contact with the cooling medium located in the protective housing 4, good cooling is ensured, so that thermal problems cannot occur.
  • the housing part 18c is not in contact with the cooling medium over its entire length.
  • the insulator 20 is namely attached to a radially outward flange 32 of the shaft-shaped housing part 18c.
  • the shaft-shaped housing part 18c and the housing part 18a thus delimit a radially outwardly open annular space, in which a schematically indicated deflection coil 31 is arranged, which serves to generate a magnetic deflection field for the electron beam 10, which is perpendicular to the plane of the drawing in FIG. 1 distracts.
  • the deflection coil, with its connections labeled Us is connected to a deflection circuit, not shown, which allows a current corresponding to the desired deflection of the electron beam 10 to flow through the deflection coil 31.
  • the deflection coil 31 can be very close to the electron beam 10 and thus only a low power is required to deflect the electron beam.
  • the power loss of the deflection coil 31 can be easily transferred to the cooling medium located in the protective housing 4.
  • the deflection coil 31 is very compact. Furthermore, no special components are required to hold them. It is understood that the dimensions of the shaft 18c and the aperture 27 take into account the size of the deflection of the electron beam 10 by means of the deflection coil 31.
  • the dimensions of the opening provided in the housing part 18a and of the shaft-shaped housing part 18c do not necessarily have to match. There is also the possibility of making the shaft wider than the opening of the housing part 18a, but then, with increasing deviations in dimensions, essentially only the opening of the housing part 18a acts as an aperture and only the housing part 18a acts as an aperture. In this case, however, the thermal load on the housing part 18a increases since it is then no longer in direct contact with the cooling medium in the vicinity of the aperture opening 27. In contrast to that shown in FIG. 1, the end of the shaft-shaped housing part 18c can also be inserted into a corresponding bore in the housing part 18a, with the result that the diaphragm opening 27 is then only limited by the shaft-shaped housing part 18c. Nevertheless, the housing part 18a will also capture part of the backscattered electrons in this case.
  • the X-ray tube shown in FIG. 2 essentially corresponds to that described above, which is why the same or similar parts have the same reference numbers.
  • the most important difference to the X-ray tube according to FIG. 1 is that the X-ray tube according to FIG. 2 is a single-pole X-ray tube. Accordingly, the housing 3 and the rotating anode 2 have the same potential, for example earth potential.
  • At the Cathode 1 is the negative high voltage -U.
  • FIG. 3 shows another X-ray tube according to the invention, which also largely corresponds to the X-ray tube according to FIG. 1, which is why the same parts have the same reference numerals again.
  • the X-ray tube according to FIG. 3 like the one according to FIG. 1, it is a two-pole X-ray tube, but in which the housing part 18a is insulated from the other parts of the housing 3 by means of an annular insulator 30.
  • the housing part 18a is insulated from the other parts of the housing 3 by means of an annular insulator 30.
  • the housing part 18a provided with the aperture opening 27 is at the same potential, namely + U, as the rotating anode 2.
  • This explains the connection with the X-ray tube according to FIG. 2 Achieved advantages in reducing extrafocal radiation. 3 can be operated with a conventional two-pole power supply. This is particularly important if existing two-pole tubes according to the state the technology replaced by an X-ray tube according to the invention and the existing power supply is to be maintained. In the case of the embodiment according to FIG.
  • an insulator 33 carrying the cathode 1 is connected via an approximately tubular metal part 34, which is at ground potential, to a further shaft-shaped insulator 35, which in turn is connected to the housing part 18a.
  • the components mentioned are each connected to one another in a vacuum-tight manner.
  • the presence of two insulators 33, 35 means that each of the insulators only has to insulate half the tube voltage.
  • the insulator 35 can naturally only capture very few of the backscattered electrons, so that in the case of FIG. 3 practically only the housing part 18a has an aperture effect.
  • a plurality of deflection coils can also be arranged on the shaft-shaped housing part 18c or the shaft-shaped insulator 35, which preferably deflect the electron beam 10 in different directions.

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  • X-Ray Techniques (AREA)
EP91107516A 1990-06-08 1991-05-08 Tube à rayons X Withdrawn EP0460421A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP90110895 1990-06-08
EP90110895 1990-06-08

Publications (1)

Publication Number Publication Date
EP0460421A1 true EP0460421A1 (fr) 1991-12-11

Family

ID=8204075

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91107516A Withdrawn EP0460421A1 (fr) 1990-06-08 1991-05-08 Tube à rayons X

Country Status (2)

Country Link
EP (1) EP0460421A1 (fr)
JP (1) JPH0521028A (fr)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4124294A1 (de) * 1991-07-22 1993-01-28 Siemens Ag Roentgenroehre fuer die computertomographie
WO1997047163A1 (fr) * 1996-06-06 1997-12-11 Varian Associates, Inc. Appareil de production de rayons x a dispositif de transfert de chaleur
DE19645053A1 (de) * 1996-10-31 1998-05-14 Siemens Ag Röntgenröhre
DE19648051A1 (de) * 1996-11-20 1998-05-28 Siemens Ag Vakuumgehäuse für eine Elektronenröhre
DE19731982C1 (de) * 1997-07-24 1998-12-10 Siemens Ag Röntgenröhre mit Mitteln zur magnetischen Ablenkung
DE19731985C1 (de) * 1997-07-24 1998-12-10 Siemens Ag Röntgenröhre mit magnetischer Ablenkung des Elektronenstrahls
EP0929907A1 (fr) * 1997-08-06 1999-07-21 Varian Associates, Inc. Appareil generateur de rayons x haute performance avec systeme de refroidissement
US6128367A (en) * 1997-07-24 2000-10-03 Siemens Aktiengesellschaft X-ray tube
WO2002045122A2 (fr) * 2000-12-01 2002-06-06 Koninklijke Philips Electronics N.V. Fenetre a plaque froide menagee dans un module radiologique a bati metallique
EP1784837A2 (fr) * 2004-09-03 2007-05-16 Varian Medical Systems Technologies, Inc. Structure de blindage et assemblage de commande de point focal pour un dispositif a rayons x

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5216506B2 (ja) * 2008-09-29 2013-06-19 株式会社東芝 回転陽極型ｘ線管装置
US8712015B2 (en) * 2011-08-31 2014-04-29 General Electric Company Electron beam manipulation system and method in X-ray sources
JP6078249B2 (ja) * 2012-07-13 2017-02-08 ブルカー・エイエックスエス株式会社 Ｘ線回折装置

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3942015A (en) * 1973-11-01 1976-03-02 National Research Development Corporation Rotating-anode x-ray tube
EP0009946A1 (fr) * 1978-10-02 1980-04-16 Pfizer Inc. Tube à rayons X
DE8713042U1 (de) * 1987-09-28 1989-01-26 Siemens AG, 1000 Berlin und 8000 München Röntgenröhre

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3942015A (en) * 1973-11-01 1976-03-02 National Research Development Corporation Rotating-anode x-ray tube
EP0009946A1 (fr) * 1978-10-02 1980-04-16 Pfizer Inc. Tube à rayons X
DE8713042U1 (de) * 1987-09-28 1989-01-26 Siemens AG, 1000 Berlin und 8000 München Röntgenröhre

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4124294A1 (de) * 1991-07-22 1993-01-28 Siemens Ag Roentgenroehre fuer die computertomographie
DE4143490C2 (de) * 1991-07-22 1999-04-15 Siemens Ag Verfahren zum Betrieb einer Röntgenröhre
WO1997047163A1 (fr) * 1996-06-06 1997-12-11 Varian Associates, Inc. Appareil de production de rayons x a dispositif de transfert de chaleur
EP1727405A3 (fr) * 1996-06-06 2006-12-27 Varian Medical Systems, Inc. Appareil de production de rayons-X avec un dispositif de transfert de chaleur
EP1727405A2 (fr) * 1996-06-06 2006-11-29 Varian Medical Systems, Inc. Appareil de production de rayons-X avec un dispositif de transfert de chaleur
DE19645053C2 (de) * 1996-10-31 1999-11-11 Siemens Ag Röntgenröhre
DE19645053A1 (de) * 1996-10-31 1998-05-14 Siemens Ag Röntgenröhre
US5898755A (en) * 1996-10-31 1999-04-27 Siemens Aktiengesellschaft X-ray tube
DE19648051A1 (de) * 1996-11-20 1998-05-28 Siemens Ag Vakuumgehäuse für eine Elektronenröhre
US5909479A (en) * 1996-11-20 1999-06-01 Siemens Akiengesellschaft Vacuum housing for an electron tube
DE19731985C1 (de) * 1997-07-24 1998-12-10 Siemens Ag Röntgenröhre mit magnetischer Ablenkung des Elektronenstrahls
US6055294A (en) * 1997-07-24 2000-04-25 Siemens Aktiengesellschaft X-ray tube with magnetic deflection of the electron beam
US6091799A (en) * 1997-07-24 2000-07-18 Siemens Aktiengesellschaft X-ray tube with means for magnetic deflection
US6128367A (en) * 1997-07-24 2000-10-03 Siemens Aktiengesellschaft X-ray tube
DE19731982C1 (de) * 1997-07-24 1998-12-10 Siemens Ag Röntgenröhre mit Mitteln zur magnetischen Ablenkung
EP0929907A1 (fr) * 1997-08-06 1999-07-21 Varian Associates, Inc. Appareil generateur de rayons x haute performance avec systeme de refroidissement
WO2002045122A2 (fr) * 2000-12-01 2002-06-06 Koninklijke Philips Electronics N.V. Fenetre a plaque froide menagee dans un module radiologique a bati metallique
WO2002045122A3 (fr) * 2000-12-01 2002-10-03 Koninkl Philips Electronics Nv Fenetre a plaque froide menagee dans un module radiologique a bati metallique
EP1784837A2 (fr) * 2004-09-03 2007-05-16 Varian Medical Systems Technologies, Inc. Structure de blindage et assemblage de commande de point focal pour un dispositif a rayons x
EP1784837A4 (fr) * 2004-09-03 2011-04-20 Varian Med Sys Inc Structure de blindage et assemblage de commande de point focal pour un dispositif a rayons x

Also Published As

Publication number Publication date
JPH0521028A (ja) 1993-01-29

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