METHOD, COMPUTING UNIT, CT SYSTEM AND C-ARM SYSTEM FOR REDUCING METAL ARTIFACTS IN CT IMAGE DATASETS

• US 20130039556A1
• Filed: 07/31/2012
• Published: 02/14/2013
• Est. Priority Date: 08/10/2011
• Status: Active Grant

• Current Assignee: Siemens Healthineers AG (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Kachelriess, Marc, Meyer, Esther, Raupach, Rainer
• Granted Patent: US 8,891,885 B2
• Time in Patent Office: Days
• US Class Current: 382/131
• CPC Class Codes: A61B 6/00 Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment instruments measuring radiation intensity for application in the field of nuclear medicine, e.g. in vivo counting, G01T1/161; apparatus for taking X-ray photographs G03B42/02
• CPC Class Codes: A61B 6/03 Computed tomography [CT] echo-tomography A61B8/14
• CPC Class Codes: A61B 6/5282 due to scatter
• CPC Class Codes: G06T 11/008 Specific post-processing after tomographic reconstruction, e.g. voxelisation, metal artifact correction
• CPC Class Codes: G06T 2207/10081 Computed x-ray tomography [CT]
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening

Abstract

A method is disclosed for reducing metal artifacts in CT image datasets. An embodiment of the method includes reconstructing a first CT image dataset with and a second CT image dataset without metal artifact correction, weighted summation of a high-pass-filtered first and a high-pass-filtered second CT image dataset plus a low-pass-filtered second CT image dataset, wherein the weightings are dependent on the proximity to metal in the CT image datasets. A computing unit, a CT system and a C-arm system designed to execute the method are also disclosed.

Claims

1. A method for reducing metal artifacts in CT image datasets, comprising:

reconstructing a first CT image dataset with metal artifact correction;

reconstructing a second CT image dataset without metal artifact correction; and

weighted summing a high-pass-filtered version of the first CT image dataset and a high-pass-filtered version of the second CT image dataset plus a low-pass-filtered version of the second CT image dataset, the weightings being dependent on proximity to metal in the first and second CT image datasets.

7. A computing unit, comprising:

a program memory configured to store program code; and

a processor configured to execute the program codes, the program code being configured to execute, when run on the processor, the method of claim 1 during operation.

8. A CT system comprising the computing unit of claim 7.

9. A C-arm system comprising the computing unit of claim 7.

10. The method of claim 1, the first CT image dataset is adaptively filtered with a noise filter before the high-pass filtering in respect of a noise or a signal-to-noise ratio that is present, wherein a high noise or low signal-to-noise ratio requires strong filtering and vice versa.

11. The method of claim 1, wherein, in the second CT image dataset, the metal artifact correction is generated by a normalized sinogram interpolation.

15. 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.

2. A method for reducing metal artifacts in CT image data, comprising:

using detector data from a scan of an object with incorporated metal;

reconstructing a first CT image dataset which dispenses with a metal artifact correction,

filtering the first CT image dataset with a high-pass filter to generate a high-pass-filtered first CT image dataset;

extracting a CT image dataset which exclusively shows metal from one of the first CT image dataset and high-pass-filtered first CT image dataset and generating a metal-weighting function or metal-weighting mask such that image regions with metal are relatively heavily weighted and image regions without metal are relatively slightly weighted;

reconstructing a second CT image dataset using metal artifact correction;

filtering the second CT image dataset with the high-pass filter to generate a high-pass-filtered second CT image dataset;

filtering he second CT image dataset with a low-pass filter, complementary to the high-pass filter, to generate a low-pass-filtered second CT image dataset;

summing a results image from the low-pass-filtered second CT image dataset, the metal-weighted high-pass-filtered first CT image dataset and the complementarily metal-weighted high-pass-filtered second CT image dataset; and

at least one of storing and outputting the results image.

3. The method of claim 2, wherein the detector data is adaptively filtered with a noise filter before the reconstruction of at least one of the first and second CT image datasets in respect of a noise or a signal-to-noise ratio that is present, wherein a high noise or low signal-to-noise ratio requires strong filtering and vice versa.

4. The method of claim 2, the first CT image dataset is adaptively filtered with a noise filter before the high-pass filtering in respect of a noise or a signal-to-noise ratio that is present, wherein a high noise or low signal-to-noise ratio requires strong filtering and vice versa.

5. The method of claim 2, wherein, in the second CT image dataset, the metal artifact correction is generated by a normalized sinogram interpolation.

6. The method of claim 2, wherein the metal-weighting function or metal-weighting mask is determined such that in image regions containing metal or their immediate vicinity a weighting of 1 is present and the weighting diminishes continuously to 0 as the distance from the metal increases.

12. A computing unit, comprising:

a program memory configured to store program code; and

a processor configured to execute the program codes, the program code being configured to execute, when run on the processor, the method of claim 2 during operation.

13. A CT system comprising the computing unit of claim 12.

14. A C-arm system comprising the computing unit of claim 12.

16. A computer readable medium including program segments for, when executed on a computer device, causing the computer device to implement the method of claim 2.