US-12628261-B2 - Operating a filament of an X-ray tube

Abstract

The present invention relates to operating a filament of an X-ray tube. In order to provide X-ray tubes with improved wear out, a control device ( 10 ) for pulsed operation of a generator for an X-ray tube is provided. The X-ray tube may be controlled to provide a plurality of X-ray pulses, wherein two subsequent pulses are temporally separated by an emission pause. The emission pause comprises at least a first part and a second part. A filament current is provided to a cathode filament of the X-ray tube such that, in the emission pause between two subsequent pulses, during a first part of the pause a first filament current is provided and during a second part of the pause a second filament current is provided, the first filament current being lower than the second filament current. By operating the filament in this way, the filament temperature can be reduced, resulting in significantly less wear and longer lifetime of the X-ray tube.

Inventors

• Hans Peter Sprong

Assignees

• KONINKLIJKE PHILIPS N.V.

Dates

Publication Date

20260512

Application Date

20221216

Priority Date

20211221

Claims (20)

1. 1 . A control device for pulsed operation of a generator for an X-ray tube, the control device comprising: a processor in communication with memory, the processor configured to: provide a signal for an X-ray imaging run comprising a plurality of X-ray pulses for acquiring at least one X-ray image; control the generator to provide a filament current to generate heat in a filament of a cathode of the X-ray tube to reach a desired emission current during an X-ray pulse, control the generator to provide the plurality of X-ray pulses, each two subsequent X-ray pulses of the plurality of X-ray pulses temporally separated by an emission pause, the emission pause comprising at least a first part and a second part; and adjust the filament current in the emission pause between the two subsequent pulses, providing a first filament current for the first part of the pause and a second filament current for the second part of the pause, the first filament current being lower than the second filament current.
2. 2 . The control device according to claim 1 , wherein the processor is configured to provide the filament current at an operational level during an X-ray pulse and wherein the first filament current is lower than the operational level and the second filament current is higher than the operational level.
3. 3 . The control device according to claim 1 , wherein the processor is configured to control the generator such that the first filament current and the second filament current result are repeatedly applied during at least a part of the emission pauses between subsequent pulses of the plurality of X-ray pulses.
4. 4 . The control device according to claim 1 , wherein the processor is configured to control the generator such that the duration of the first portion and the duration of the second portion are determined based on a calculation weighting results from a boost curve and results from a blank curve to retrieve blank time and boost time for a given pulse pause duration while still reaching the operational filament temperature during the pulses.
5. 5 . The control device according to claim 1 , wherein the processor is configured to control the generator such that the blank curve and the boost curve are interpolated from look-up tables.
6. 6 . The control device according to claim 5 , wherein the look-up tables are updated based on a detected wear of the filament; and wherein the results from the look-up table are corrected for the detected wear of the filament.
7. 7 . The control device according to claim 1 , wherein, to generate the electron beam with the desired emission current for generating the X-ray pulses, the processor is configured to control the generator to provide a plurality of voltage pulses corresponding to the X-ray pulses.
8. 8 . The control device according to claim 1 , wherein the processor is configured to control the generator such that after the second filament current, an operational filament current is provided during the pulse.
9. 9 . The control device according to claim 1 , wherein the processor is configured to control the generator such that a heat-up filament current is provided before a sequence of pulses is provided; and wherein the heat-up filament current is equal to the second filament current.
10. 10 . The control device according to claim 1 , wherein the processor is configured to control the generator such that a filament current during the first part of the pause is sufficient to provide that a predetermined minimal filament current is maintained as effective current throughout the pause.
11. 11 . A generator for pulsed voltage supply of an X-ray tube, the generator comprising: the control device according to claim 1 ; an electric power input connectable to an electric power supply configured to provide an input in form of electric energy for operating the X-ray tube, wherein the electric power supply is connected to the electric transformer arrangement; an electric transformer arrangement is configured to transform the electric input into suitable DC high-voltage and suitable electric current for pulsed operation of the X-ray tube; and wherein an electric power output is configured to provide the suitable high-voltage and the suitable electric currents, wherein the electric power output is connectable to the X-ray tube, wherein the control device is configured to control said generator components.
12. 12 . An X-ray imaging system, comprising: an X-ray tube for generating X-ray radiation; a control device according to claim 1 ; and a generator for voltage and current supply of the X-ray tube; wherein the X-ray tube comprises an anode and a cathode; wherein the cathode comprises at least one cathode filament for emitting at least one electron beam towards the anode; and wherein the control device controls a pulsed operation of the cathode filament by controlling the electric transformer arrangement of the generator.
13. 13 . A method for operating a generator of an X-ray tube in a pulsed manner, the method comprising: providing a signal for an X-ray imaging run comprising a plurality of X-ray pulses for acquiring at least one X-ray image; providing a filament current to generate heat in a filament of a cathode of the X-ray tube to reach a desired emission current during an X-ray pulse; generating an electron beam with a desired emission current from the cathode towards an anode of the X-ray tube under the influence of a voltage between the anode and the cathode to generate the plurality of X-ray pulse with desired properties; providing a plurality of pulses to generate the electron beam with the desired emission current for generating the plurality of X-ray pulses, wherein each two subsequent pulses of the plurality of X-ray pulses are temporally separated by an emission pause; wherein the emission pause comprises at least a first part and a second part; and adjusting, in the emission pause between the two subsequent pulses, the filament current thereby providing a first filament current for the first part of the pause and a second filament current for the second part of the pause, wherein the first filament current is lower than the second filament current.
14. 14 . The method according to claim 13 , further comprising providing the filament current at an operational level during an X-ray pulse and wherein the first filament current is lower than the operational level and the second filament current is higher than the operational level.
15. 15 . The method according to claim 13 , further comprising controlling the generator such that the first filament current and the second filament current result are repeatedly applied during at least a part of the emission pauses between subsequent pulses of the plurality of X-ray pulses.
16. 16 . The method according to claim 13 , further comprising controlling the generator such that the duration of the first portion and the duration of the second portion are determined based on a calculation weighting results from a boost curve and results from a blank curve to retrieve blank time and boost time for a given pulse pause duration while still reaching the operational filament temperature during the pulses.
17. 17 . A non-transitory computer readable medium having stored a computer program comprising instructions which, when executed by a processor, cause the processor to: provide a signal for an X-ray imaging run comprising a plurality of X-ray pulses for acquiring at least one X-ray image; control the generator to provide a filament current to generate heat in a filament of a cathode of the X-ray tube to reach a desired emission current during an X-ray pulse, control the generator to provide the plurality of X-ray pulses, each two subsequent X-ray pulses of the plurality of X-ray pulses temporally separated by an emission pause, the emission pause comprising at least a first part and a second part; and adjust the filament current in the emission pause between the two subsequent pulses, providing a first filament current for the first part of the pause and a second filament current for the second part of the pause, the first filament current being lower than the second filament current.
18. 18 . The non-transitory computer readable medium according to claim 17 , wherein the instruction, when executed by the processor, further cause the processor to provide the filament current at an operational level during an X-ray pulse and wherein the first filament current is lower than the operational level and the second filament current is higher than the operational level.
19. 19 . The non-transitory computer readable medium according to claim 17 , wherein the instruction, when executed by the processor, further cause the processor to control the generator such that the first filament current and the second filament current result are repeatedly applied during at least a part of the emission pauses between subsequent pulses of the plurality of X-ray pulses.
20. 20 . The non-transitory computer readable medium according to claim 17 , wherein the instruction, when executed by the processor, further cause the processor to control the generator such that the duration of the first portion and the duration of the second portion are determined based on a calculation weighting results from a boost curve and results from a blank curve to retrieve blank time and boost time for a given pulse pause duration while still reaching the operational filament temperature during the pulses.

Description

CROSS-REFERENCE TO PRIOR APPLICATIONS This application is the U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2022/086279, filed on Dec. 16, 2022, which claims the benefit of European Patent Application No. 21216304.2, filed on Dec. 21, 2021. These applications are hereby incorporated by reference herein. FIELD OF THE INVENTION The present invention relates to operating a filament of an X-ray tube and relates in particular to a control device for pulsed operation of a generator for an X-ray tube, to a generator for voltage supply of an X-ray tube, to an X-ray imaging system and to a method for operating a generator of an X-ray tube in a pulsed manner. BACKGROUND OF THE INVENTION X-ray imaging is considered an important imaging modality in medical imaging. X-ray tubes are used to generate X-ray radiation that passes through a subject and impinges on an X-ray detector. For various reasons, for example restrictions in certain flat X-ray detectors, X-ray radiation may need to be generated in a pulsed manner. In such pulsed X-ray image acquisition, X-ray images are acquired using a series of short X-ray pulses. Such a series of pulses is called an imaging run. A crucial part in an X-ray tube are the cathode filaments. The filaments need to have a specific, elevated temperature to reach the desired emission current during an X-ray pulse. X-ray tubes used e.g. in cardio-vascular X-ray systems may show a wear-out of their cathode filaments. The wear-out may be the result of evaporation of the tungsten they consist of. SUMMARY OF THE INVENTION There may thus be a need to provide X-ray tubes in particular for pulsed operation with increased field life. The object of the present invention is solved by the subject-matter of the independent claims: further embodiments are incorporated in the dependent claims. It should be noted that the following described aspects of the invention apply also for the control device for operation of a generator for an X-ray tube, for the generator for voltage supply of an X-ray tube, for the X-ray imaging system and for the method for operating a generator of an X-ray tube. According to an embodiment, a control device for pulsed operation of a generator for an X-ray tube is provided. The control device comprises a data input and a controller. The data input is configured to provide a signal for an X-ray imaging run comprising a plurality of X-ray pulses for acquiring at least one X-ray image. The controller is configured to control the generator to provide a filament current to generate heat in a filament of a cathode of the X-ray. The generator is configured to provide the plurality of X-ray pulses, whereby each two subsequent pulses of the plurality of X-ray pulses are temporally separated by an emission pause. The emission pause comprises at least a first part and a second part. For providing the filament current, the controller is further configured to control the generator to adjust, in the emission pause between the two subsequent pulses, the filament current thus providing at least a first filament current during the first part of the pulse and a second filament current for the second part of the pause. The first filament current is lower than the second filament current. In a preferred embodiment, wherein the controller is configured to provide the filament current at an operational level during an X-ray pulse, the first filament current is lower than the operational level and/or the second filament current is higher than the operational level. In accordance therewith, providing the first filament current is also referred to as “blanking” and providing the second filament current is also referred to as “boosting” hereinafter. Thus, in effect, during the first part of the emission pause, the filament temperature decreases from its operational value and the second filament current may be provided as an intermediate heat-up current to restore the temperature of the filament to its operational value during the second part of the emission pause. That is, the operational value of the filament temperature corresponds to the temperature needed for emitting an electron beam during an X-ray pulse. By operating the filament in this way, during pulsed operation of the X-ray tube, the filament temperature between pulses will be lower than it would be when the filament current was kept continuously at an operational level, thus causing significantly less wear, without interfering with the quality of the X-ray beam or other noticeable effects. As an effect, the filament is subject to lower temperatures between pulses, resulting in less tungsten evaporation and thus reduced wear. According to an example, the controller is configured to control the generator such that the first and the second filament currents are repeatedly applied during at least a part of the emission pauses, resulting in a repeated cooling-down and heating-up of the filament during