EP4177927A1 - Röntgenröhre - Google Patents

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Publication number
EP4177927A1
EP4177927A1 EP21207192.2A EP21207192A EP4177927A1 EP 4177927 A1 EP4177927 A1 EP 4177927A1 EP 21207192 A EP21207192 A EP 21207192A EP 4177927 A1 EP4177927 A1 EP 4177927A1
Authority
EP
European Patent Office
Prior art keywords
grids
pair
voltage
cathode
controller
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Withdrawn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
EP21207192.2A
Other languages
English (en)
French (fr)
Inventor
Roland Proksa
Ruth WIEBUS
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.)
Koninklijke Philips NV
Original Assignee
Koninklijke Philips NV
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 Koninklijke Philips NV filed Critical Koninklijke Philips NV
Priority to EP21207192.2A priority Critical patent/EP4177927A1/de
Priority to PCT/EP2022/078335 priority patent/WO2023083546A1/en
Publication of EP4177927A1 publication Critical patent/EP4177927A1/de
Withdrawn legal-status Critical Current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
    • H01J35/14—Arrangements for concentrating, focusing, or directing the cathode ray
    • H01J35/153—Spot position control
    • 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
    • H01J35/06—Cathodes
    • H01J35/066—Details of electron optical components, e.g. cathode cups
    • 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
    • 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
    • H05G1/58—Switching arrangements for changing-over from one mode of operation to another, e.g. from radioscopy to radiography, from radioscopy to irradiation or from one tube voltage to another

Definitions

  • the present invention relates to an X-ray tube and an X-ray generation system.
  • Some X-Ray tubes for medical CT imaging use electrostatic electron beam forming in combination with temperature limited emission.
  • the emission current depends on the filament temperature and electrical heating is typically used to control the emission current.
  • the electron beam is steered by electrical grids for focal spot sizing and positioning.
  • the control of the emission via the temperature of the filament is a relatively slow process because the heating and cooling of the filament requires a certain amount of time. This slow emission, via control of the current flowing through the filament, is a problem for some applications.
  • the emission is controlled via the filament temperature, the tube voltage and the voltage of the grids also impact the emission.
  • an X-ray tube comprising a cathode, the cathode comprising:
  • the first pair of girds are located at opposite sides of the electron emitter filament.
  • the second pair of girds are located at opposite sides of the electron emitter filament closer to the electron emitter filament than the first pair of grids.
  • the cathode is configured such that a voltage or an average voltage of the first pair of grids is different to a voltage of the second pair of grids.
  • the grids of the first pair of grids are configured to be at different voltages to each other.
  • the grids of the second pair of grids are configured to be at the same voltage to each other.
  • the cathode is configured such that the voltage or the average voltage of the first pair of grids is greater than the voltage of the second pair of grids.
  • the cathode is configured such that the voltage or the average voltage of the first pair of grids is two times greater than the voltage of the second pair of grids.
  • the cathode is configured such that the voltage or the average voltage of the first pair of grids is ten times greater than the voltage of the second pair of grids.
  • the cathode is configured such that the voltage or the average voltage of the first pair of grids is thirty times greater than the voltage of the second pair of grids.
  • an X-ray generation system comprising:
  • the cathode comprises:
  • the first pair of girds are located at opposite sides of the electron emitter filament; and The second pair of girds are located at opposite sides of the electron emitter filament closer to the filament than the first pair of grids; and In a first mode of operation:
  • the controller is configured to control the low-medium supply to apply different voltages to the grids of the first pair of grids.
  • the controller is configured to control the low-medium supply to apply different voltages to the grids of the first pair of grids at a same average voltage to steer the electron beam.
  • the controller is configured to control the low-medium supply to apply a voltage of different magnitudes to the grids of the first pair of grids or an average voltage of different magnitudes to the grids of the first pair of grids.
  • the controller is configured to control the low-medium supply to apply a same voltage of different magnitudes to the grids of the second pair of grids.
  • a reduction in the magnitude of the voltage magnitude applied to the grids of the second pair of grids in both the first mode and second mode of operation for a fixed voltage or average voltage applied to the grids of the first pair of grids is configured to increase a current of the electron beam and increase a focal spot size.
  • the controller is configured to maintain a focal spot size between the first mode of operation and the second mode of operation through application of a voltage of different magnitudes between the grids of the first pair of grids and the grids of the second pair of grids in the first mode of operation and in the second mode of operation.
  • the controller is configured to control the low-medium supply to apply a first voltage magnitude between the grids of the first pair of grids and the grids of the second pair of grids in the first mode of operation and to control the low-medium supply to apply a second voltage magnitude between the grids of the first pair of grids and the grids of the second pair of grids in the second mode of operation, wherein the second magnitude is less than the first magnitude.
  • Fig. 1 shows an example of an X-ray tube 10 comprising a cathode 20.
  • the cathode 20 comprises an electron emitter filament 30, a first pair of grids 40, and a second pair of grids 50.
  • the first pair of girds are located at opposite sides of the electron emitter filament.
  • the second pair of girds are located at opposite sides of the electron emitter filament closer to the electron emitter filament than the first pair of grids.
  • the cathode is configured such that a voltage or an average voltage of the first pair of grids is different to a voltage of the second pair of grids.
  • the grids of the first pair of grids are configured to be at different voltages to each other.
  • the grids of the second pair of grids are configured to be at the same voltage to each other.
  • the cathode is configured such that the voltage or the average voltage of the first pair of grids is greater than the voltage of the second pair of grids.
  • the cathode is configured such that the voltage or the average voltage of the first pair of grids is two times greater than the voltage of the second pair of grids.
  • the cathode is configured such that the voltage or the average voltage of the first pair of grids is ten times greater than the voltage of the second pair of grids.
  • the cathode is configured such that the voltage or the average voltage of the first pair of grids is thirty times greater than the voltage of the second pair of grids.
  • Fig. 2 shows an example of an X-ray generation system 100.
  • the system 100 comprises an anode 60, a cathode 20, a high voltage supply 70, a low-medium voltage supply 80, and a controller 90.
  • the cathode comprises an electron emitter filament 30, a first pair of grids 40, and a second pair of grids 50.
  • the first pair of girds are located at opposite sides of the electron emitter filament.
  • the second pair of girds are located at opposite sides of the electron emitter filament closer to the filament than the first pair of grids.
  • the controller is configured to control the low-medium supply to apply different voltages to the grids of the first pair of grids.
  • the controller is configured to control the low-medium supply to apply different voltages to the grids of the first pair of grids at a same average voltage to steer the electron beam.
  • the controller is configured to control the low-medium supply to apply a voltage of different magnitudes to the grids of the first pair of grids or an average voltage of different magnitudes to the grids of the first pair of grids.
  • the controller is configured to control the low-medium supply to apply a same voltage of different magnitudes to the grids of the second pair of grids.
  • a reduction in the magnitude of the voltage magnitude applied to the grids of the second pair of grids in both the first mode and second mode of operation for a fixed voltage or average voltage applied to the grids of the first pair of grids is configured to increase a current of the electron beam and increase a focal spot size.
  • the controller is configured to maintain a focal spot size between the first mode of operation and the second mode of operation through application of a voltage of different magnitudes between the grids of the first pair of grids and the grids of the second pair of grids in the first mode of operation and in the second mode of operation.
  • the controller is configured to control the low-medium supply to apply a first voltage magnitude between the grids of the first pair of grids and the grids of the second pair of grids in the first mode of operation and to control the low-medium supply to apply a second voltage magnitude between the grids of the first pair of grids and the grids of the second pair of grids in the second mode of operation, wherein the second magnitude is less than the first magnitude.
  • Fig. 3 shows a typical cathode design.
  • the filament is embedded in a cup with steering grids on both sides.
  • the grid voltages are used to position and size the focal spot (FS).
  • the common part of the voltages defines the FS size.
  • High voltages will constrict the emitted electron beam and form a small focal spot (and vice versa).
  • a voltage difference between the grids can be used to position the focal spot.
  • the common voltage will also impact the emission by changing the electrical field.
  • GridVioltage 1 is represented by "A”
  • GridVoltage 2 is represented by "B”.
  • the grids can be at different voltages indicated by the A and B.
  • this shows an embodiment where the inner grids are close to the filament and can efficiently control the emission even with relatively small voltages.
  • the outer grids are mainly used to shape the focal spot and to correct for the focal spot impact of the inner grids.
  • Fig. 5 shows two emission current (mA) at the top and FS size (mm) at the bottom curves as a function of the X-ray tube voltage (KV) for one filament temperature using a conventional tube design.
  • the two curves belong to two different grid voltages (705V, 1150V). These grid voltages have been selected to get the same focal spot size (1.2mm) at 80kV and 140kV in this example.
  • the emission current goes down from about 570mA (@ 140kV, grid 1150V) to 480mA (@ 80kV, grid 705V).
  • the grid voltage may be switched forth and back during the tube voltage transition.
  • Fig. 6 shows the emission current (top) and focal spot size (bottom) for the new design of cathode. This shows what happens if the grid voltages for the inner grids 50 (GridVoltage3 "50 - C") is different form the outer grids 40 (Gridvoltage1 "40 - A” and GridVoltage2 "40 - B”). It can be seen how the emission current increases from about 480mA to 750mA for smaller voltages on the inner grids. However, at the same time the focal spot gets larger, where it is to be noted that the voltage on the outer grids 40 has been kept constant.
  • Fig. 7 it is shown how this unwanted focal spot (FS) enlargement can be compensated with higher voltages on the outer grids 40.
  • the outer grid voltages have been selected to maintain the desired FS size of 1.2mm at 80kVp (bottom).
  • the emission currents however are very different.
  • the maximal improvement of the current relative to the conventional cathode design is a gain of about 35% (from 480mA to 650mA). This is a significant improvement for kVp-S and it enables ultra-fast dose modulation.
  • Fig. 8 the differences can be visualized with an electron track simulation. It shows in effect the conventional setting (left) with all grids (outer and inner) at 705V to generate a FS size of 1.2mm - this then equates to the conventional design with only one pair of grids.
  • the image to the right shows the improved case associated with the new cathode design with 50V on the inner grids 50 and 1500V on the outer grids.
  • the electron cloud is much larger close to the filament indicating the increased current.

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  • X-Ray Techniques (AREA)
EP21207192.2A 2021-11-09 2021-11-09 Röntgenröhre Withdrawn EP4177927A1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP21207192.2A EP4177927A1 (de) 2021-11-09 2021-11-09 Röntgenröhre
PCT/EP2022/078335 WO2023083546A1 (en) 2021-11-09 2022-10-12 X-ray tube

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP21207192.2A EP4177927A1 (de) 2021-11-09 2021-11-09 Röntgenröhre

Publications (1)

Publication Number Publication Date
EP4177927A1 true EP4177927A1 (de) 2023-05-10

Family

ID=78617175

Family Applications (1)

Application Number Title Priority Date Filing Date
EP21207192.2A Withdrawn EP4177927A1 (de) 2021-11-09 2021-11-09 Röntgenröhre

Country Status (2)

Country Link
EP (1) EP4177927A1 (de)
WO (1) WO2023083546A1 (de)

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5031200A (en) * 1989-08-07 1991-07-09 General Electric Cgr Sa Cathode for an X-ray tube and a tube including such a cathode
US5125019A (en) * 1989-03-24 1992-06-23 General Electric Cgr Sa X-ray scanning tube with deflecting plates
US6438207B1 (en) * 1999-09-14 2002-08-20 Varian Medical Systems, Inc. X-ray tube having improved focal spot control
US20070274457A1 (en) * 2006-05-23 2007-11-29 General Electric Company Method and apparatus to control radiation tube focal spot size
US20110051884A1 (en) * 2009-08-28 2011-03-03 Kabushiki Kaisha Toshiba X-ray tube and x-ray ct apparatus
DE102012211285B3 (de) * 2012-06-29 2013-10-10 Siemens Aktiengesellschaft Röntgenröhre und Verfahren zum Betrieb einer Röntgenröhre
DE102012211287B3 (de) * 2012-06-29 2013-10-10 Siemens Aktiengesellschaft Verfahren zum Betrieb einer Röntgenröhre
US20200000423A1 (en) * 2017-02-01 2020-01-02 Esspen Gmbh Computer tomograph
US20200343069A1 (en) * 2019-04-24 2020-10-29 Shanghai United Imaging Healthcare Co., Ltd. Systems and methods for focus control in x-rays
WO2020229254A1 (en) * 2019-05-14 2020-11-19 Koninklijke Philips N.V. Maintaining a given focal spot size during a kvp switched spectral (multi-energy) imaging scan

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8938050B2 (en) * 2010-04-14 2015-01-20 General Electric Company Low bias mA modulation for X-ray tubes
US8396185B2 (en) * 2010-05-12 2013-03-12 General Electric Company Method of fast current modulation in an X-ray tube and apparatus for implementing same

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5125019A (en) * 1989-03-24 1992-06-23 General Electric Cgr Sa X-ray scanning tube with deflecting plates
US5031200A (en) * 1989-08-07 1991-07-09 General Electric Cgr Sa Cathode for an X-ray tube and a tube including such a cathode
US6438207B1 (en) * 1999-09-14 2002-08-20 Varian Medical Systems, Inc. X-ray tube having improved focal spot control
US20070274457A1 (en) * 2006-05-23 2007-11-29 General Electric Company Method and apparatus to control radiation tube focal spot size
US20110051884A1 (en) * 2009-08-28 2011-03-03 Kabushiki Kaisha Toshiba X-ray tube and x-ray ct apparatus
DE102012211285B3 (de) * 2012-06-29 2013-10-10 Siemens Aktiengesellschaft Röntgenröhre und Verfahren zum Betrieb einer Röntgenröhre
DE102012211287B3 (de) * 2012-06-29 2013-10-10 Siemens Aktiengesellschaft Verfahren zum Betrieb einer Röntgenröhre
US20200000423A1 (en) * 2017-02-01 2020-01-02 Esspen Gmbh Computer tomograph
US20200343069A1 (en) * 2019-04-24 2020-10-29 Shanghai United Imaging Healthcare Co., Ltd. Systems and methods for focus control in x-rays
WO2020229254A1 (en) * 2019-05-14 2020-11-19 Koninklijke Philips N.V. Maintaining a given focal spot size during a kvp switched spectral (multi-energy) imaging scan

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