Maintaining a given focal spot size during a kVp switched spectral (multi-energy) imaging scan

Patent metadata

Field	Value
Publication number	US-11963284-B2
Application number	US-202017610831-A
Country	US
Kind code	B2
Filing date	May 6, 2020
Priority date	May 14, 2019
Publication date	Apr 16, 2024
Grant date	Apr 16, 2024

Abstract

An imaging system (202) includes an X-ray radiation source (210) configured to emit radiation that traverses an examination region. The imaging system further includes a controller (220). The controller is configured to control an X-ray tube peak voltage of the X-ray radiation source to switch between at least two different X-ray tube peak voltages during a kVp switched spectral scan. The controller is further configured to control a grid voltage of the X-ray radiation source to follow the X-ray tube peak voltage during the spectral scan. The controller adjusts the grid voltage based on a predetermined mapping between a currently applied X-ray tube peak voltage and a corresponding grid voltage for a given focal spot size, thereby maintaining the given focal spot size throughout the spectral scan.

First claim

The invention claimed is:

1. An imaging system, comprising:
an X-ray radiation source configured to emit radiation that traverses an examination region; and
a controller configured to:
control an X-ray tube peak voltage of the X-ray radiation source to switch between at least two different X-ray tube peak voltages during a kVp switched spectral scan; and
control a grid voltage of the X-ray radiation source to follow the X-ray tube peak voltage during the spectral scan, wherein the controller is configured to adjust the grid voltage based on a predetermined mapping between a currently applied X-ray tube peak voltage and a corresponding grid voltage for a particular focal spot size such that the particular focal spot size is maintained throughout the spectral scan, wherein the mapping is between X-ray tube peak voltages and grid voltages for each respective focal spot size of a plurality of focal spot sizes.

2. The system of claim 1 , wherein the X-ray radiation source comprises:
a cathode including:
a focusing cup with grid electrodes; and
at least one filament; and

an anode; and

wherein the controller is configured to alternately apply the at least two different X-ray tube peak voltages across the cathode and the anode and the grid voltages across the grid electrodes.

3. The system of claim 1 , wherein the mapping is represented in a look-up table, and the controller includes the look-up table.

4. The system of claim 1 , wherein the mapping is represented as a polynomial, and the controller includes the polynomial.

5. The system of claim 1 , wherein the at least two different X-ray tube peak voltages include 80 kilovolts and 140 kilovolts.

6. The system of claim 1 , wherein at least two different grid voltages include grid voltages in a range of 400-800 volts and 1000-2000 volts.

7. The system of claim 6 , wherein a bandwidth of the grid voltage is less than 10 megahertz.

8. The system of claim 1 , wherein a transition from a lower X-ray tube peak voltage to a higher X-ray tube peak voltage is in a range of 50 to 100 microseconds.

9. The system of claim 1 , wherein a transition from a higher X-ray tube peak voltage to a lower X-ray tube peak voltage is in a range of 150 to 300 microseconds.

10. The system of claim 1 , further comprising:
a detector array configured to detect radiation that traverses the examination region and generate at least first and second sets of line integrals for the at least two different X-ray tube peak voltages.

11. The system of claim 10 , further comprising:
a projection domain decomposer configured to decompose the at least first and second sets of line integrals into at least two basis components of interest; and
a reconstructor configured to reconstruct the at least two basis components of interest to generate spectral volumetric image data.

12. The system of claim 10 , further comprising:
a reconstructor configured to reconstruct the at least first and second sets of line integrals to generate low and high volumetric image data; and
an image domain decomposition module configured to decompose the low and high volumetric image data into volumetric image data of interest.

13. An image processing method, comprising:
controlling an X-ray tube peak voltage of an X-ray radiation source to switch between at least two different X-ray tube peak voltages during a kVp switched spectral scan; and
controlling a grid voltage of the X-ray radiation source to follow the X-ray tube voltage peak during the spectral scan based on a predetermined mapping between X-ray tube peak voltages and grid voltages for a particular focal spot size in order to maintain the particular focal spot size throughout the spectral scan, wherein the mapping is between X-ray tube peak voltages and grid voltages for each respective focal spot size of a plurality of focal spot sizes.

14. The method of claim 13 , wherein the X-ray radiation source comprises:
a cathode including:
a focusing cup with grid electrodes; and
at least one filament; and

an anode, and further comprising:
alternately applying the X-ray tube peak voltages across the cathode and the anode and the grid voltages across the grid electrodes.

15. The method of claim 13 , wherein the predetermined mapping is stored in a controller controlling the X-ray radiation source.

16. A non-transitory computer-readable storage medium storing computer executable instructions, which when executed by a processor, cause the processor to:
control an X-ray tube peak voltage of an X-ray radiation source to switch between at least two different X-ray tube peak voltages during a kVp switched spectral scan; and
control a grid voltage of the X-ray radiation source to follow the X-ray tube peak voltage during the spectral scan based on a predetermined mapping between X-ray tube peak voltages and grid voltages for a particular focal spot size to maintain the particular focal spot size throughout the spectral scan, wherein the mapping is between X-ray tube peak voltages and grid voltages for each respective focal spot size of a plurality of focal spot sizes.

17. The non-transitory computer-readable storage medium of claim 16 , wherein the X-ray radiation source comprises:
a cathode, including:
a focusing cup with grid electrodes; and
at least one filament; and

an anode, and further comprising:
wherein the processor alternately applies the X-ray tube peak voltages and the grid voltages respectively across the cathode and the anode and the grid electrodes.

18. The non-transitory computer-readable storage medium of claim 16 , wherein the predetermined mapping is stored in a memory accessed by the processor.

Assignees

• Koninklijke Philips Nv

Inventors

• Daerr Heiner
• David Bernd Rudi

Classifications

• H05G1/58 Primary

  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} · CPC title

• H01J35/147 Primary

  Spot size control · CPC title

• H05G1/52

  Target size or shape; Direction of electron beam, e.g. in tubes with one anode and more than one cathode · CPC title

• A61B6/482

  involving multiple energy imaging · CPC title

• G01N23/046 Primary

  using tomography, e.g. computed tomography [CT] · CPC title