Systems and methods for x-ray tomography having retrograde focal positioning

Patent metadata

Field	Value
Publication number	US-10076292-B2
Application number	US-201514885383-A
Country	US
Kind code	B2
Filing date	Oct 16, 2015
Priority date	Oct 16, 2015
Publication date	Sep 18, 2018
Grant date	Sep 18, 2018

Abstract

A tomography apparatus includes a multi-focal point x-ray source, a support to travel a trajectory path, a detector having a plurality of pixels, where one of the multi-focal point x-ray source, the detector, and an item-under-test move on the support. A control processor controls a change in the focal point of the x-ray source at discrete points, or continuously, within a measurement region, the focal point change in a direction retrograde to the support arm travel, a detector memory accumulates a digital value representative of a signal charge from at least a portion of the plurality of pixels, the control processor reconstructs a volumetric image of the item-under-test by processing the detector memory contents. A method for continuous tomosynthesis and a computer-readable medium are also disclosed.

First claim

The invention claimed is:

1. A tomography apparatus comprising:
a multi-focal point x-ray source;
a support for the source configured to travel a pre-determined trajectory path;
a detector having a plurality of pixels, at least one of the multi-focal point x-ray source, the detector, and an item-under-test mounted on the support to move relative to one another;
a control processor configured to execute computer-readable instructions that cause the control processor to change the focal point of the x-ray source at discrete points within a measurement region in a direction retrograde to the support arm travel along the trajectory path, wherein the focal point of the x-ray source is changed at three or more discrete points and wherein displacement of the focal point is within a predetermined range along the measurement region of the trajectory path;
a detector memory configured to accumulate a digital value representative of a signal charge from at least a portion of the plurality of pixels exposed to a portion of the x-ray beam;
the control processor configured to reconstruct a volumetric image of the item-under-test by processing contents of the detector memory with a reconstruction process function.

2. The tomography apparatus of claim 1 , including the control processor configured to provide control signals to a multi-focal source control electronics unit, the multi-focal source control electronics unit configured to control the multi-focal point x-ray source focal position.

3. The tomography apparatus of claim 1 , the trajectory path extending from a first extreme position to a second extreme position, the control processor configured to provide velocity control signals to control the velocity of the support.

4. The tomography apparatus of claim 3 , the velocity control signals set to a first velocity in measurement regions along the trajectory path, and a second velocity between measurement regions, the second velocity being greater than the first velocity.

5. The tomography apparatus of claim 4 , the detector memory accumulating data during discrete measurement points within the measurement region.

6. The tomography apparatus of claim 1 , the displacement of the focal point corresponds to focal spot width of the x-ray beam.

7. The tomography apparatus of claim 6 , wherein maximum displacement of the focal point is within 0.5 mm.

8. A method of continuous motion tomosynthesis, the method comprising:
exposing an item-under test to a programmed intensity x-ray beam as one of a multi-focal x-ray source, a detector, and the item-under-test travel a pre-determined trajectory path, the detector having a plurality of pixels;
maintaining about a constant first velocity within a measurement region along the trajectory path;
changing a focal point of the multi-focal point x-ray source at discrete points along the measurement region in a direction retrograde to the travel along the trajectory path, wherein the focal point of the x-ray source is changed at three or more discrete points and wherein displacement of the focal point is within a predetermined range along the measurement region of the trajectory path;
accumulating in at least a portion of the plurality of pixels a signal charge from at least a portion of the x-ray beam;
recording in a detector memory buffer the accumulated signal charge from the plurality of pixels at discrete points, the signal charge recorded as digital frame images, the digital frame images representing raw baseline data; and
reconstructing a volumetric image of the item-under-test by applying a reconstruction process function to the recorded digital frame images.

9. The method of claim 8 , including providing control signals to a multi-focal source control electronics unit, the multi-focal source control electronics unit controlling the multi-focal point x-ray source focal position.

10. The method of claim 8 , controlling velocity along the trajectory path from a first extreme position to a second extreme position to a first velocity in measurement regions and a second velocity between measurement regions, the second velocity being greater than the first velocity.

11. The method of claim 8 , accumulating data at discrete measurement points within the measurement region.

12. The method of claim 8 , the displacement of the focal point corresponds to focal spot width of the x-ray beam.

13. The method of claim 8 , obtaining sub-views within the measurement region by reading the detector charges.

14. The method of claim 13 , the focal point changing within a sub-view in an order repeated along the measurement region.

15. A non-transitory computer readable medium having stored thereon instructions which when executed by a processor cause the processor to perform a method of continuous motion tomosynthesis, the method comprising:
exposing an item-under test to a programmed intensity x-ray beam as one of a multi-focal x-ray source, a detector, and the item-under-test travel a pre-determined trajectory path, the detector having a plurality of pixels;
maintaining about a constant first velocity within a measurement region along the trajectory path;
changing a focal point of the multi-focal point x-ray source at discrete points along the measurement region in a direction retrograde to the travel along the trajectory path, wherein the focal point of the x-ray source is changed at three or more discrete points and wherein displacement of the focal point is within a predetermined range along the measurement region of the trajectory path;
accumulating in at least a portion of the plurality of pixels a signal charge from at least a portion of the x-ray beam;
recording in a detector memory buffer the accumulated signal charge from the plurality of pixels at discrete points, the signal charge recorded as digital frame images, the digital frame images representing raw baseline data; and
reconstructing a volumetric image of the item-under-test by applying a reconstruction process function to the recorded digital frame images.

16. The non-transitory computer readable medium of claim 15 , which cause the control processor to provide control signals to a multi-focal source control electronics unit, the multi-focal source control electronics unit controlling the multi-focal point x-ray source focal position.

17. The non-transitory computer readable medium of claim 15 , which cause the control processor to control velocity along the trajectory path from a first extreme position to a second extreme position to a first velocity in measurement regions and a second velocity between measurement regions, the second velocity being greater than the first velocity.

18. The non-transitory computer readable medium of claim 15 , which cause the control processor to accumulate data at discrete measurement points within the measurement region.

19. The non-transitory computer readable medium of claim 15 , which cause the control processor to select the displacement of the focal point corresponding to the focal spot width of the x-ray beam.

20. The non-transitory computer readable medium of claim 15 , which cause the control processor to obtain sub-views within the measurement region by reading the detector charges, and change the focal point within a sub-view in an order repeated along the measurement region.

Assignees

• Gen Electric

Inventors

• Tkaczyk John Eric
• Klausz Remy Andre
• Jacob Biju

Classifications

• G06T12/20

  Inverse problem, i.e. transformations from projection space into object space · CPC title

• G06T12/10

  Image preprocessing, e.g. calibration, positioning of sources or scatter correction · CPC title

• H01J35/24

  Tubes wherein the point of impact of the cathode ray on the anode or anticathode is movable relative to the surface thereof · CPC title

• A61B6/54

  Control of apparatus or devices for radiation diagnosis · CPC title

• A61B6/4021 Primary

  involving movement of the focal spot · CPC title