CT IMAGE RECONSTRUCTION OF A MOVING EXAMINATION OBJECT

• US 20100303326A1
• Filed: 05/24/2010
• Published: 12/02/2010
• Est. Priority Date: 05/26/2009
• Status: Active Grant

• Current Assignee: Siemens Healthineers AG (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Allmendinger, Thomas
• Granted Patent: US 8,737,701 B2
• Time in Patent Office: Days
• US Class Current: 382/131
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/33 specially adapted for cooperation with other devices
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/4014 arranged in multiple source-detector units
• CPC Class Codes: A61B 6/4441 the rigid structure being a C-arm or U-arm
• CPC Class Codes: A61B 6/481 involving the use of contrast agents
• CPC Class Codes: A61B 6/482 involving multiple energy imaging
• CPC Class Codes: A61B 6/504 for diagnosis of blood vessels, e.g. by angiography
• CPC Class Codes: A61B 6/507 for determination of haemodynamic parameters, e.g. perfusion CT
• CPC Class Codes: G06T 11/005 Specific pre-processing for tomographic reconstruction, e.g. calibration, source positioning, rebinning, scatter correction, retrospective gating
• CPC Class Codes: G06T 2211/412 Dynamic

Abstract

A method is disclosed for reconstructing image data of a moving examination object from measured data, the measured data having been acquired during a rotating movement of a radiation source of a computed tomography system around the examination object. In at least one embodiment, first image data are determined from the measured data. Movement information is determined from the first image data by forming the difference between images. Time instants of little movement of the examination object are determined from the movement information, the determined time instants being dependent on the location or site within the examination object. Finally, second image data are reconstructed taking the determined time instants into account. These data can be output as result images.

Claims

1. A method for reconstructing image data of a moving examination object from measured data, the measured data being acquired during a rotating movement of a radiation source of a computed tomography system around the examination object, the method comprising:

determining first image data from the measured data;

determining movement information by forming a difference between images from the determined first image data;

determining time instants of relatively little movement of the examination object from the determined movement information, the determined time instants being dependent on a site within the examination object; and

reconstructing second image data taking into account the determined time instants.

2. The method as claimed in claim 1, wherein

at least one function is defined which indicates a time instant of little movement based on the site within the examination object.

3. The method as claimed in claim 1, wherein

two different functions are defined, each of the two different functions specifies a time instant of little movement based on the site within the examination object.

4. The method as claimed in claim 2, wherein

the at least one function represents a spline function.

5. The method as claimed in claim 4, wherein

the spline function has a plurality of sampling points that are equidistant in the space domain.

6. The method as claimed in claim 2, wherein

the at least one function is calculated by minimizing a function containing the movement information.

7. The method as claimed in claim 6, wherein

the function that is to be minimized contains at least one of a parameter for limiting the slope and a parameter for limiting the curvature of the at least one function that is to be calculated.

8. The method as claimed in claim 6, wherein

time instants are varied for the purposes of the minimization.

9. The method as claimed in claim 1, wherein

the first image data contain images of the entire examination object for each time instant of a movement cycle of the examination object.

10. The method as claimed in claim 1, wherein

the movement information indicates how strongly specific sites of the examination object move at specific time instants within a movement cycle of the examination object.

11. The method as claimed in claim 1, wherein

the difference is formed between images which represent the same section of the examination object at different times within a movement cycle of the examination object.

12. The method as claimed in claim 11, wherein

the difference is formed for different sections of the examination object.

13. The method as claimed in claim 1, wherein

the movement information forms a two-dimensional time- and space-dependent matrix.

14. The method as claimed in claim 1, wherein

the difference between images is formed by calculating individual differences between an individual image value of a first image and a corresponding individual image value of a second image in each case.

15. The method as claimed in claim 14, wherein

the difference between the first and the second image is formed by summing the individual differences.

16. The method as claimed in claim 1, wherein

parts of the measured data corresponding to the determined time instants are selected and used for reconstructing the second image data.

17. A control and computing unit for reconstructing image data of a moving examination object from measured data of a CT system, the control and computing unit comprising:

a program memory for storing program code, the program code being able to perform the method as claimed in claim 1, when executed on the control and computing unit.

18. A CT system comprising the control and computing unit as claimed in claim 17.

19. A computer program comprising program code segments for performing the method as claimed in claim 1 when the computer program is executed on a computer.

20. A computer program product, comprising program code segments of a computer program stored on a computer-readable data medium, for performing the method as claimed in claim 1 when the computer program is executed on a computer.

21. The method as claimed in claim 3, wherein

the at least one function represents a spline function.

22. The method as claimed in claim 21, wherein

the spline function has a plurality of sampling points that are equidistant in the space domain.

23. A computer readable medium including program segments for, when executed on a computer device, causing the computer device to implement the method of claim 1.