Method, device, and computer program product for capturing projection images with optimized movement path

Patent metadata

Field	Value
Publication number	US-9833215-B2
Application number	US-201314431286-A
Country	US
Kind code	B2
Filing date	Sep 25, 2013
Priority date	Sep 26, 2012
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

A method, device, and computer program product for capturing projection images of an object are provided. An x-ray beam source is moved by a control unit on a path into a plurality of positions, in which an x-ray beam is transmitted. An x-ray beam detector is moved by the control unit into a plurality of positions, in which the x-ray beam, penetrating the object, is detected. The x-ray beam source and/or the x-ray beam detector are moved on a calculated path around the object, at a constant distance between the x-ray beam source and the x-ray beam detector or the object. The path is described by an nth degree polynomial and determined by the control unit through an optimization of a path along the central x-ray beam. The polynomial is selected such that a safety clearance with respect to the object is maintained and a distance between the x-ray beam detector and the object is minimized.

First claim

The invention claimed is:

1. A method for recording projection pictures of an object to be imaged by way of an imaging device that comprises an x-ray beam source, an x-ray beam detector, and a control unit, the method comprising:
moving the x-ray beam source by the control unit on a path into several positions, in which in each of the several positions an x-ray beam departing from the x-ray beam source is emitted in a cone-beam-shape about a central x-ray beam;
moving the x-ray beam detector, with the displacement of the x-ray beam source, by the control unit into several positions, in which in each of the several positions the x-ray beam which departs from the x-ray beam source and penetrates the object to be imaged is captured for recording a projection picture;
wherein at least one of the x-ray beam source and the x-ray beam detector are displaced on a path about the object to be imaged, the path being described by a polynomial of the nth degree and computed by the control unit by way of an optimization of a predefined path, and with a variable distance between the x-ray beam source and a surface of the object to be imaged provided by the optimization of the predefined path, the distance determined along the central x-ray beam, wherein the polynomial is selected such that a safety distance to the object to be imaged is maintained and, simultaneously, a distance between the x-ray beam detector and the object to be imaged is minimized.

2. The method according to claim 1 , wherein the polynomial is defined by at least two grid points and is determined by way of at least one of an optimization while taking into account the grid points and an optimization of a predefined circular path.

3. The method according to claim 1 , wherein a maximal height of the path of the x-ray beam detector is determined by a maximal opening angle (α) of the path of the x-ray beam source, the opening angle being determined by departing from a middle point of the object to be imaged, and wherein a starting point and an end point of the path of the x-ray beam detector lies opposite a starting point and an end point of the path of the x-ray beam source along the central x-ray beam running through the middle point of the object to be imaged.

4. The method according to claim 1 , wherein the path of the movement of at least one of the x-ray beam source and the x-ray beam detector is at least one of:
an open path that is open such that the open path does not completely enclose the object to be imaged; and
a reversal point path that has at least one reversal point, in which a direction change takes place, and wherein a first path section up to the reversal point is spatially different to a second path section from the reversal point.

5. The method according to claim 1 , wherein at least one of the x-ray beam detector and the x-ray beam source is moved in relation to at least two axes which are perpendicular to one another.

6. The method according to claim 1 , wherein an inclination (β) of the x-ray beam source is set such that a beamed surface of the x-ray beam detector is maximized at a fixed angle of the cone beam.

7. The method according to claim 1 , wherein at least one of the movements of the x-ray beam source and of the x-ray beam detector is carried out in an automated manner by way of the control unit.

8. The method according to claim 1 , wherein an evaluation unit computes a three-dimensional reconstruction of the object to be imaged, from the projection pictures.

9. A computer program product stored on a non-transitory machine-readable medium and executed on a computation unit, the computer program product comprising a command sequence for carrying out the method according to claim 1 , when executed on the computation unit.

10. A device for recording projection pictures of an object to be imaged, the device comprising:
an x-ray beam source configured to emit x-ray radiation in a cone-beam-shape about a central x-ray beam;
an x-ray beam detector configured to capture emitted x-ray radiation penetrating the object to be imaged; and
a control unit configured to move the x-ray beam detector and the x-ray beam source into several positions and to record a projection picture in each of the several positions, wherein the control unit is configured to move the x-ray beam source and the x-ray beam detector on a path about the object to be imaged, the path being described by a polynomial of the nth degree and computed by the control unit by way of an optimization of a predefined path, and with a variable distance between the x-ray beam source and a surface of the object to be imaged provided by the optimization of the predefined path, the distance determined along the central x-ray beam, wherein the polynomial in each case is selected such that a safety distance to the object to be imaged is maintained and, simultaneously, a distance between the x-ray beam detector and the object to be imaged is minimized.

Assignees

• Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E V
• Charite—Universitätsmedizin Berlin
• Fraunhofer Ges Forschung

Inventors

• Stopp Fabian
• Käseberg Marc
• Engel Sebastian
• Keeve Erwin
• Fehlhaber Felix
• Uhlmann Eckart

Classifications

• A61B6/589

  Setting distance between source unit and patient · CPC title

• A61B6/588 Primary

  Setting distance between source unit and detector unit · CPC title

• A61B6/035

  Mechanical aspects of CT · CPC title

• A61B6/4452

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

• A61B2560/0266

  for monitoring or limiting apparatus function · CPC title