EP0173047A2 - Tube à rayons X - Google Patents

Tube à rayons X Download PDF

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Publication number
EP0173047A2
EP0173047A2 EP85108795A EP85108795A EP0173047A2 EP 0173047 A2 EP0173047 A2 EP 0173047A2 EP 85108795 A EP85108795 A EP 85108795A EP 85108795 A EP85108795 A EP 85108795A EP 0173047 A2 EP0173047 A2 EP 0173047A2
Authority
EP
European Patent Office
Prior art keywords
electron beam
target
deflection
ray tube
impact
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Withdrawn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
EP85108795A
Other languages
German (de)
English (en)
Other versions
EP0173047A3 (fr
Inventor
Helge Carlsen
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.)
Scanray AS
Original Assignee
Scanray AS
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 Scanray AS filed Critical Scanray AS
Publication of EP0173047A2 publication Critical patent/EP0173047A2/fr
Publication of EP0173047A3 publication Critical patent/EP0173047A3/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Withdrawn legal-status Critical Current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
    • H01J35/02—Details
    • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/14—Arrangements for concentrating, focusing, or directing the cathode ray
    • H01J35/147—Spot size control
    • 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

Definitions

  • the invention relates to an X-ray tube of the type specified in the preamble of claim 1.
  • an X-ray tube of the type in question is known in which, for the purpose of pulse operation, the electron beam is deflected during the pulse pauses from the part of the target surfaces from which the X-ray radiation exits through the exit window of the X-ray tube during the pulse duration.
  • the target is designed as a body with an essentially wedge-shaped surface, the one wedge surface facing away from the target window facing the exit window of the X-ray tube and the other wedge surface facing away from the exit window, so that no X-ray radiation emerges from there. This is intended to ensure that the electron current flows continuously, while the X-ray radiation is pulse-shaped.
  • the electron beam is passed through zigzag paths on the surface of the target facing away from the exit window, in order in this way to distribute the heat generated during the pulse pauses over large areas of the target.
  • the emitted X-rays are not affected by this, since the areas of the target that are swept in this way face away from the exit window.
  • a macro focal spot that is to say a focal spot with a relatively large surface area of 2x2 mm, for example, by designing the cathode or by appropriately guiding or defocusing the electron beam to achieve the desired surface area of the focal spot.
  • a disadvantage here is, however, that the intensity distribution of the electron beam impinging on the macro focal spot and thus also the X-ray radiation resulting therefrom is very uneven. This leads to a reduction in the image quality.
  • a macro focal spot is, however, desirable because of the high overall intensity of the emitted X-rays, particularly when the radiation source and the object to be imaged are far away.
  • the invention has for its object to provide an X-ray tube of the type in question, which has a large focal spot with a uniform intensity distribution.
  • the invention is based on the basic idea of forming a large focal spot, that is to say a macro focal spot, by rapidly deflecting a small focal spot in the manner of deflecting the electron beam in a television picture tube.
  • the paths traversed by the small focal spot can lie closely next to one another, and since the small focal spot has a constant intensity during the deflection, the total area covered by the small focal spot also shines with the same intensity at all points. This creates a macro focal spot with an even intensity distribution.
  • the basic teaching according to the invention also has the advantage that the boundary of the focal spot can largely be shaped as desired. Only the deflection voltages or deflection currents have to be shaped accordingly.
  • the focal spot can therefore be square, elongated or stretched rectangular, or also delimited round or elliptically. With a round or elliptical boundary, the point of impact of the electron beam on the target expediently runs through a circular or elliptical spiral path. In extreme cases, it is even possible to deflect the electron beam only in to be provided in one direction so that a linear focal spot is formed with very different dimensions in two different directions.
  • the drawing shows, partially in section, an X-ray tube with a housing 1, which is connected to a line 2, which is connected to a pump, not shown, for lowering the pressure in the interior 3 of the X-ray tube.
  • a cathode 4 in the form of a small filament, which is bent in a V-shape and with its tip facing an anode 5 and a target 6.
  • a grid cap 7 is arranged in the region of the cathode 4, which projects into an opening 8 in the grid cap 7 and whose tip is approximately aligned with the front boundary of the opening 8. From this front boundary, the grille cap 7 widens in a conical surface 9.
  • a hole 11 runs through the hole anode 5 and continues into an interior 12 of the metallic tube 10 with a variable inside diameter.
  • a focusing coil 13 is arranged in the area of the metallic tube 10.
  • Deflection coils 14 and 15 are also provided, with which the electron beam can be deflected.
  • the target 6 has an inclination to the axis 16 of the X-ray tube indicated by a dash-dotted line and is held in a holder 17 which is connected to a cooling source (not shown) via pipes 18 and 19 for the purpose of cooling the target.
  • an exit window 20 in the housing Radially next to the surface of the target 6 there is an exit window 20 in the housing through which X-ray radiation emanating from the target 6 can exit in the area between two dashed lines 21 and 22.
  • the axis of the x-ray radiation is indicated by a center line 23.
  • a schematically illustrated AC voltage source 24 is connected via a line 25 to the deflection coil 14 and generates a sawtooth-shaped alternating current indicated by a curve 26 in the deflection coil 14, so that the electron beam is deflected laterally in a direction predetermined by the position of the deflection coil 14.
  • Another AC voltage source 27 is connected to the deflection coil 15 via a line 28 and feeds it with a sawtooth-shaped current indicated by a curve 29.
  • the deflection coil 15 is oriented offset by 90 ° to the deflection coil 14, so that the deflection by the deflection coil 15 is perpendicular to that by the deflection coil 14.
  • the frequency of the sawtooth-shaped current generated by the AC voltage source 24 is low in relation to that of the AC voltage source 27 and corresponds to the image deflection frequency in a television tube.
  • the frequency of the sawtooth current of the AC voltage source 27 is significantly higher and corresponds to the line deflection frequency of a television tube.
  • FIG. 2 schematically shows a top view against the target 6 and schematically illustrates an area 30 swept in a row by the electron beam.
  • the individual paths of the electron beam are of course much closer together, just like with a television picture.
  • the direction of image deflection is horizontal in the drawing, the direction of line deflection is vertical.
  • Fig. 3 corresponds essentially to Fig. 2 and shows an elongated rectangular surface 31 which forms the macro focal spot.
  • FIG. 4 also corresponds to FIG. 2, but a surface 32 forming the macro focal spot is elongated in the vertical direction and delimited essentially in a rectangular shape.
  • FIG. 5 again shows a plan view of the target 6, but in this exemplary embodiment a circular focal spot 33 is formed by a spiral path of the electron beam.
  • the bills deliver Voltage sources 24 and 27 to the deflection coils 14 and 15 are continuously increasing sinusoidal currents.
  • magnetic deflection is useful. In principle, however, it is also within the scope of the invention to use other types of distraction, e.g. electrostatic deflection.

Landscapes

  • X-Ray Techniques (AREA)
EP85108795A 1984-08-27 1985-07-13 Tube à rayons X Withdrawn EP0173047A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3431434 1984-08-27
DE19843431434 DE3431434A1 (de) 1984-08-27 1984-08-27 Roentgenroehre

Publications (2)

Publication Number Publication Date
EP0173047A2 true EP0173047A2 (fr) 1986-03-05
EP0173047A3 EP0173047A3 (fr) 1988-03-16

Family

ID=6243978

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85108795A Withdrawn EP0173047A3 (fr) 1984-08-27 1985-07-13 Tube à rayons X

Country Status (3)

Country Link
EP (1) EP0173047A3 (fr)
DE (1) DE3431434A1 (fr)
DK (1) DK368685A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1371970A2 (fr) * 2002-06-12 2003-12-17 Agilent Technologies, Inc. Procédé et dispositif d'imagerie aux rayons-X à 3D pour exploration à vitesse rapide d'articles de grande taille

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4125926C1 (en) * 1991-08-05 1992-08-27 Siemens Ag, 8000 Muenchen, De X=ray tube for computer tomography - has vacuum housing with anode and cathode to emit and focus electron beam

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3176137A (en) * 1961-10-31 1965-03-30 Licentia Gmbh Crt x-ray generator with beam velocity modulation for equalizing radiation
US3852605A (en) * 1972-12-27 1974-12-03 Jeol Ltd Control circuitry for preventing damage to the target of a scanning x-ray generator
DE2813657A1 (de) * 1978-03-30 1979-10-04 Bahram Dr Med Bahrami Zeilen-roentgen mit oder ohne zusammenbuendelung bzw. parallelstellung der roentgenstrahlen
DE3222515A1 (de) * 1982-06-16 1984-03-22 Feinfocus Röntgensysteme GmbH, 3050 Wunstorf Feinfokus-roentgenroehre

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3176137A (en) * 1961-10-31 1965-03-30 Licentia Gmbh Crt x-ray generator with beam velocity modulation for equalizing radiation
US3852605A (en) * 1972-12-27 1974-12-03 Jeol Ltd Control circuitry for preventing damage to the target of a scanning x-ray generator
DE2813657A1 (de) * 1978-03-30 1979-10-04 Bahram Dr Med Bahrami Zeilen-roentgen mit oder ohne zusammenbuendelung bzw. parallelstellung der roentgenstrahlen
DE3222515A1 (de) * 1982-06-16 1984-03-22 Feinfocus Röntgensysteme GmbH, 3050 Wunstorf Feinfokus-roentgenroehre

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1371970A2 (fr) * 2002-06-12 2003-12-17 Agilent Technologies, Inc. Procédé et dispositif d'imagerie aux rayons-X à 3D pour exploration à vitesse rapide d'articles de grande taille
EP1371970A3 (fr) * 2002-06-12 2004-01-02 Agilent Technologies, Inc. Procédé et dispositif d'imagerie aux rayons-X à 3D pour l'exploration à vitesse rapide d'articles de grande taille
US7106830B2 (en) 2002-06-12 2006-09-12 Agilent Technologies, Inc. 3D x-ray system adapted for high speed scanning of large articles

Also Published As

Publication number Publication date
EP0173047A3 (fr) 1988-03-16
DK368685D0 (da) 1985-08-14
DE3431434A1 (de) 1986-03-06
DK368685A (da) 1986-02-28

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Inventor name: CARLSEN, HELGE