Systems and methods for computed tomography

Patent metadata

Field	Value
Publication number	US-2024138786-A1
Application number	US-202218051433-A
Country	US
Kind code	A1
Filing date	Oct 31, 2022
Priority date	Oct 31, 2022
Publication date	May 2, 2024
Grant date	—

Abstract

Methods and systems are provided for increasing a quality of computed tomography (CT) images. In one embodiment, a CT system comprises an X-ray tube and an X-ray controller including one or more processors having executable instructions stored in a non-transitory memory of the CT system that, when executed, cause the one or more processors to, during a first view of a CT scan of an object, focus an electron beam at a first focal spot on a target of the X-ray tube, the first focal spot of a first size; during a second view of the CT scan, focus the electron beam at a second focal spot on the target, the second focal spot of a second size different from the first size; and reconstruct an image of the object from projection data including the first view and the second view.

First claim

1 . A computed tomography (CT) system, comprising:
an X-ray tube including a cathode and a target, and an X-ray controller including one or more processors having executable instructions stored in a non-transitory memory of the CT system that, when executed, cause the one or more processors to: during a first view of a CT scan of an object, focus an electron beam generated by the cathode at a first focal spot on a target of the X-ray tube, the first focal spot of a first size; during a second view of the CT scan, focus the electron beam at a second focal spot on the target, the second focal spot of a second size, the second size different from the first size; and reconstruct an image of the object from projection data including the first view and the second view.

2 . The CT system of claim 1 , wherein the CT scan is an mA modulated scan.

3 . The CT system of claim 2 , wherein the first view and the second view are within a continuous X-ray exposure.

4 . The CT system of claim 2 , wherein the first size is selected based on a first amount of current applied to the cathode in accordance with an mA modulation profile, and the second size is selected based on a second amount of current applied to the cathode in accordance with the mA modulation profile, the second amount different from the first amount.

5 . The CT system of claim 4 , wherein:
the first size is selected to be a smallest size possible for the first amount of current that does not exceed a power limit for an amount of concentrated energy within the first focal spot on the target; and the second size is selected to be a smallest size possible for the second amount of current that does not exceed a power limit for an amount of concentrated energy within the second focal spot on the target.

6 . The CT system of claim 2 , wherein projection view data of the CT scan is divided into a plurality of groups of views, and the electron beam is focused to generate a focal spot of a same size within a group of views of the plurality of groups of views, and different sizes between the plurality of groups of views.

7 . The CT system of claim 6 , wherein the different sizes of focal spots are selected from a number of available focal spot sizes configured for the CT system.

8 . The CT system of claim 7 , wherein:
in a first condition, where an amount of current applied to the cathode at a view is the same as an amount of current applied to the cathode at an immediately preceding view, a size of a focal spot selected for the view is the same as a size of a focal spot selected for the immediately preceding view; and in a second condition, where the amount of current applied to the cathode at the view is different from the amount of current applied to the cathode at the immediately preceding view, the size of the focal spot selected for the view is the different from the size of the focal spot selected for the immediately preceding view.

9 . The CT system of claim 7 , wherein a focal spot size is selected based at least partly on one of a view angle of the projection view and a specific portion of an anatomy of a subject being scanned by the CT system.

10 . The CT system of claim 1 , wherein:
focusing the electron beam at the first focal spot further comprises performing a first adjustment to at least one of electrostatic controls and/or electromagnetic controls of the X-Ray controller, where performing the first adjustment to the electrostatic controls includes adjusting a first voltage delivered at an electrode of the CT system, and performing the first adjustment to the electromagnetic controls includes adjusting one or more currents delivered to one or more magnets of the CT system; and focusing the electron beam at the second focal spot further comprises performing a second adjustment to at least one of the electrostatic controls and/or electromagnetic controls, the second adjustment different from the first adjustment.

11 . The CT system of claim 10 , wherein the first adjustment is based on a first amount of current applied to the cathode in accordance with a mA modulation profile, and the second adjustment is based on a second amount of current applied to the cathode in accordance with the mA modulation profile.

12 . The CT system of claim 1 , wherein prior to initiating the CT scan, the CT system is calibrated for a plurality of different focal spots, each different focal spot corresponding to an exclusive current range at which the focal spot is used.

13 . The CT system of claim 12 , wherein calibrating the CT system for the plurality of different focal spots further comprises calibrating the CT system for a corresponding current range of each focal spot of the plurality of different focal spots, and not calibrating the CT system for the focal spot for current ranges outside the corresponding current range.

14 . A method for a computed tomography (CT) system, the method comprising:
reconstructing an image of a scanned object from projection view data acquired during a scan performed by the CT system, wherein: the image is reconstructed from a first portion of the projection view data, the first portion acquired using a focal spot of a first size, and a second portion of the projection view data, the second portion acquired using a focal spot of a second size.

15 . The method of claim 14 , wherein the first portion of projection view data is corrected using a first calibration vector, the first calibration vector selected based on the focal spot of the first size; and the second portion of projection view data is corrected using a second calibration vector, the second calibration vector selected based on the focal spot of the second size.

16 . The method of claim 14 , further comprising, during a backprojection process of image reconstruction, adjusting a resolution of a projection view through an object scanned by the CT system as a function of focal spot size for the projection view.

17 . The method of claim 16 , wherein adjusting the resolution of the projection view as a function of focal spot size further comprises pre-filtering the projection view as a function of a known focal spot size for the projection view to match a spatial resolution across a plurality of views.

18 . A method, comprising:
during calibration of a computed tomography (CT) system to focus an electron beam of the CT system on a target of an X-ray tube: performing a first calibration of the CT system for a first focal spot of a first size, for a first range of kV/mA settings, and not performing the first calibration on a second range of kV/mA settings; performing a second calibration of the CT system for a second focal spot of a second size, for the second range of kV/mA settings, the second range of kV/mA settings different from the first range of kV/mA settings; and not performing the second calibration on the first range of kV/mA settings.

19 . The method of claim 18 , wherein the method is applied to the X-ray tube to generate focal spots sized in accordance with specifications of the CT system.

20 . The method of claim 18 , wherein the method is applied to the CT system to generate a plurality of calibration vectors to be applied to correct projection view data acquired by the CT system, the calibration vectors generated as a function of a size of a focal spot.

Assignees

• Ge Prec Healthcare Llc

Inventors

• Thibault Jean-Baptiste
• Londt John Howard
• Boudry John

Classifications

• G01N23/046

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

• A61B6/4452

  the source unit and the detector unit being able to move relative to each other · CPC title

• A61B6/4266

  characterised by using a plurality of detector units (A61B6/4014 takes precedence) · CPC title

• A61B6/4028 Primary

  resulting in acquisition of views from substantially different positions, e.g. EBCT · CPC title

• A61B6/4021 Primary

  involving movement of the focal spot · CPC title