X-ray device with reduced pile-up

Patent metadata

Field	Value
Publication number	US-10470723-B2
Application number	US-201615580290-A
Country	US
Kind code	B2
Filing date	Jun 23, 2016
Priority date	Jun 30, 2015
Publication date	Nov 12, 2019
Grant date	Nov 12, 2019

Abstract

The invention relates to an x-ray device (1) for imaging an object (41). A radiation detector (3) of the x-ray device includes detector elements (21) for detecting radiation, each detector element (21) comprising an adjustable sensitive volume, where an x-ray photon entering the sensitive volume produces an electric signal used for generating the image data. Further, the device comprises a control unit (9) configured to control the sensitive volume of at least one of the detector elements (21) in accordance with a geometric structure of the object (41) to be imaged in order to reduce a pile-up effect in the detector element. Moreover, the invention relates to a method for operating the device (1) and to a computer program for carrying out the method.

First claim

The invention claimed is:

1. An x-ray device for acquiring image data of an object to be imaged, the device comprising an x-ray source and a radiation detector,
the radiation detector including detector elements for detecting radiation, each detector element comprising an adjustable sensitive volume, where an x-ray photon entering the sensitive volume produces an electric signal used for generating the image data,

wherein the device further comprises a control unit configured to control the sensitive volume of at least one of the detector elements in accordance with a geometric structure of the object to be imaged.

2. The x-ray device as defined in claim 1 , wherein the control unit is configured to reduce the sensitive volume of the detector element when at least part of the detector element is located outside a shadow region created by the object in accordance with the geometric structure of the object.

3. The x-ray device as defined in claim 1 , wherein the control unit is configured to reduce the sensitive volume of the detector element when at least part of the detector element collects radiation having traversed a region of the object having a smaller x-ray attenuation coefficient than another region of the object.

4. The x-ray device as defined in claim 1 , the x-ray source and the radiation detector are configured to rotate around the object during an x-ray scan of the object.

5. The x-ray device as defined in claim 4 , wherein a control profile indicates values of a control parameter for controlling the sensitive volume of the detector element for several positions of the radiation detector during the x-ray scan, and wherein the control unit controls the sensitive volume of the detector element by varying the control parameter in accordance with the values of the parameter indicated in the control profile.

6. The x-ray device as defined in claim 5 , wherein the control unit is coupled to a storage for storing the control profile and wherein the control unit reads the control profile in connection with an execution of the x-ray scan.

7. The x-ray device as defined in claim 5 , wherein the control unit is configured to generate the control profile on the basis of one or more images of the object acquired in a further x-ray scan, particularly in a scout scan.

8. The x-ray device as defined in claim 5 , wherein the control unit is configured to generate the control profile in accordance with an estimated geometric structure of the object.

9. The x-ray device as defined in claim 8 , further comprising a rangefinder device configured to scan the object, wherein the control unit is configured to estimate the geometric structure of the object on the basis of dimensions of the object determined using the rangefinder device.

10. The x-ray device as defined in claim 5 , wherein predetermined control profiles for geometric structures for plural classes of the object are stored in the control unit and wherein the control unit is configured to select the control profile on the basis of an information about the class of the object to be imaged.

11. The x-ray device as defined in claim 1 , wherein detector element comprises a converter element producing electric charge carriers in response to an incident photon, the converter element being arranged between a cathode electrode assembly and an anode electrode assembly, the anode electrode assembly comprising at least one anode electrode for collecting charge carriers to produces an electric signal used for generating the image data and at least one steering electrode which can be held on the same or a more negative electric potential than the anode electrode.

12. The x-ray device as defined in claim 11 , wherein the sensitive volume of the detector element is reduced by bringing the electric potential of the steering electrode closer to the electric potential of the anode electrode or by making it more positive than the electric potential of the anode electrode.

13. The x-ray device as defined in claim 11 , wherein a control profile indicates values of a parameter indicative of a voltage between the anode electrode and the steering electrode for several positions of the radiation detector during an x-ray scan, and wherein the control unit is configured to control the sensitive volume of the detector element by varying the voltage in accordance with the values of the parameter indicated in the control profile.

14. A method for operating an x-ray device to acquire image data of an object to be imaged, the device comprising an x-ray source and a radiation detector, the radiation detector including detector elements for detecting radiation, each detector element comprising an adjustable sensitive volume, where an x-ray photon entering the sensitive volume produces an electric signal used for generating the image data,
wherein a control unit of the device controls the sensitive volume of at least one of the detector elements in accordance with a geometric structure of the object to be imaged.

15. A computer program executable in a processing unit of an x-ray device, the computer program comprising program code means for causing the processing unit to carry out a method as defined in claim 14 when the computer program is executed in the processing unit.

Assignees

• Koninklijke Philips Nv

Inventors

• Herrmann Christoph

Classifications

• A61B6/032 Primary

  Transmission computed tomography [CT] · CPC title

• A61B6/4035

  the source being combined with a filter or grating · CPC title

• A61B6/54

  Control of apparatus or devices for radiation diagnosis · CPC title

• A61B6/482

  involving multiple energy imaging · CPC title

• G01T1/171

  Compensation of dead-time counting losses · CPC title