Obtaining measurement information from an edge-on X-ray detector and determining the orientation of an edge-on X-ray detector with respect to the direction of incoming X-rays

Patent metadata

Field	Value
Publication number	US-9903958-B2
Application number	US-201515505303-A
Country	US
Kind code	B2
Filing date	Sep 23, 2015
Priority date	Sep 23, 2015
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

There is provided a method for at least partly determining the orientation of an edge-on x-ray detector with respect to the direction of x-rays from an x-ray source. The method includes obtaining (S 1 ) information from measurements, performed by the x-ray detector, representing the intensity of the x-rays at a minimum of two different relative positions of a phantom in relation to the x-ray detector and the x-ray source, the phantom being situated between the x-ray source and the x-ray detector and designed to embed directional information in the x-ray field when exposed to x-rays. The method also includes determining (S 2 ) at least one parameter associated with the orientation of the x-ray detector with respect to the direction of x-rays based on the obtained information from measurements and a geometrical model of the spatial configuration of the x-ray detector, x-ray source and phantom.

First claim

The invention claimed is:

1. A method for at least partly determining the orientation of an individual edge-on x-ray detector, forming part of an overall x-ray detector arrangement comprising a detector array of multiple edge-on x-ray detectors, with respect to the direction of x-rays from an x-ray source, the edge-on detector having detector elements in two directions, one of the directions having a component in the direction of the x-rays such that the edge-on detector has detector elements configured to enable measuring of x-ray intensity with spatial separation in the direction of the x-rays, said method comprising:
obtaining information from measurements, performed by the x-ray detector, representing the intensity of the x-rays at a minimum of two different relative positions of a phantom in relation to the x-ray detector and the x-ray source, the phantom being situated between the x-ray source and the x-ray detector and designed to embed directional information in the x-ray field when exposed to x-rays, a measurement producing a signal for each detector element proportional to the intensity of the x-rays passing through the respective detector element; and
determining at least one parameter associated with the orientation of the x-ray detector with respect to the direction of x-rays based on the obtained information from measurements and a geometrical model of the spatial configuration of the x-ray detector, x-ray source and phantom.

2. The method of claim 1 , wherein the geometrical model describes the position of the source, the position and orientation of the x-ray detector, the position of the phantom, and geometrical parameters representing a relative motion of the phantom in relation to the x-ray detector and the x-ray source.

3. The method of claim 1 , wherein the geometrical model is able to predict movement of a trace or shadow from the phantom with respect to the detector.

4. The method of claim 1 , wherein said at least one parameter associated with the orientation includes at least an angle between the direction of the x-rays and a line in a detector plane defined by a trace of an x-ray beam on the detector, where the x-ray beam is defined by a feature of the phantom.

5. The method of claim 4 , wherein said at least one parameter associated with the orientation further includes the orientation of said line in said detector plane.

6. The method of claim 1 , wherein the phantom comprises at least one hole and/or edge in an x-ray attenuating sheet, or comprises at least one ball bearing.

7. The method of claim 1 , wherein the determined parameter(s) associated with the orientation of the x-ray detector with respect to the direction of x-rays is/are used to improve a forward model used in image reconstruction.

8. The method of claim 1 , wherein the determined parameter(s) associated with the orientation of the x-ray detector with respect to the direction of x-rays is/are used to localize the focal spot of the x-ray tube.

9. The method of claim 8 , further comprising finding the optimal position of the focal spot from an image quality perspective.

10. The method of claim 1 , wherein the determined parameter(s) associated with the orientation of the x-ray detector with respect to the direction of x-rays is/are used to adjust an individual x-ray detector in a detector array.

11. The method of claim 1 , wherein the determined parameter(s) associated with the orientation of the x-ray detector with respect to the direction of x-rays is/are used to perform post-processing of measurement data measured by the x-ray detector.

12. The method of claim 1 , wherein the determined parameter(s) associated with the orientation of the x-ray detector with respect to the direction of x-rays is/are used to deliberately misalign detector elements of the x-ray detector in the direction of the x-rays such that an oversampling is achieved.

13. A method for obtaining measurement information from an edge-on x-ray detector forming part of an overall x-ray detector arrangement comprising a detector array of multiple edge-on x-ray detectors, the edge-on detector having detector elements in two directions, one of the directions having a component in the direction of the x-rays such that the edge-on detector has detector elements configured to enable measuring of x-ray intensity with spatial separation in the direction of x-rays from an x-ray source, said method comprising:
providing a phantom, which is configured to embed directional information in the x-ray field when exposed to x-rays, between the x-ray source and the x-ray detector;
inducing relative motion of the phantom in relation to the x-ray detector and the x-ray source; and
performing measurements of the intensity of the x-rays at a minimum of two different relative positions of the phantom in relation to the x-ray detector and the x-ray source to obtain the measurement information, a measurement producing a signal for each detector element proportional to the intensity of the x-rays passing through the respective detector element.

14. A method for estimating at least one parameter associated with the orientation of an edge-on x-ray detector with respect to the direction of x-rays based on measurement information obtained by the method of claim 13 .

15. The method of claim 14 , wherein said at least one parameter associated with the orientation of the x-ray detector with respect to the direction of x-rays is determined based on the obtained measurement information and a geometrical model of the spatial configuration of the x-ray detector, x-ray source and phantom.

16. The method of claim 14 , wherein said at least one parameter associated with the orientation includes at least an angle between the direction of the x-rays and a line in a detector plane defined by a trace of an x-ray beam on the detector, where the x-ray beam is defined by a feature of the phantom.

17. The method of claim 14 , wherein quality of the detector mounting in the gantry is evaluated based on the estimated parameter(s) associated with the orientation of the x-ray detector with respect to the direction of x-rays.

18. The method of claim 14 , wherein input parameters of a forward model of the source/detector system are calibrated based on the estimated parameter(s) associated with the orientation of the x-ray detector with respect to the direction of x-rays.

19. The method of claim 14 , wherein geometrical parameters describing the spatial configuration of the x-ray source-detector system, such as positions of projection measurements, are calibrated based on the estimated parameter(s) associated with the orientation of the x-ray detector with respect to the direction of x-rays.

20. The method of claim 14 , wherein corrections of x-ray measurement data are performed based on the estimated parameter(s) associated with the orientation of the x-ray detector with respect to the direction of x-rays.

21. A method for predicting an effect of movement of an edge-on x-ray detector and/or a focal spot of an x-ray source based on based on measurement information obtained by the method of claim 13 , wherein the measurements are made with different positions of the x-ray detector and/or the focal spot, and at least one correction for a position of the x-ray detector, and/or a focal spot of the x-ray source is computed.

22. A system configured to at least partly determine the orientation of an individual edge-on x-ray detector, forming part of an overall x-ray detector arrangement comprising

Assignees

• Prismatic Sensors Ab

Inventors

• Sjolin Martin
• Gronberg Fredrik

Classifications

• A61B6/584

  determining position of components of the apparatus or device using images of the phantom · CPC title

• A61B6/4233

  using matrix detectors · CPC title

• G01N2223/33

  scanning, i.e. relative motion for measurement of successive object-parts · CPC title

• G01B15/00

  Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons (characterised by the use of optical techniques G01B9/00, G01B11/00) · CPC title

• G01T1/24 Primary

  with semiconductor detectors · CPC title