Processing metal artifact in ct image

Patent metadata

Field	Value
Publication number	US-2016163071-A1
Application number	US-201514959486-A
Country	US
Kind code	A1
Filing date	Dec 4, 2015
Priority date	Dec 4, 2014
Publication date	Jun 9, 2016
Grant date	—

Abstract

A method for processing metal artifacts in a CT image is provided. The method may comprise: performing a first metal artifact processing on the original image to obtain a first processed image COR1 and extracting the high frequency portion of the first processed image COR1 to obtain a first high-frequency image COR1HF; performing a second metal artifact processing on the original image to obtain a second processed image COR2 and extracting the high frequency portion of the processed image COR2 second to obtain a second high-frequency image COR2HF; perform a weighted combination the first processed image COR1, the first high-frequency image COR1HF and the second high-frequency image COR2HF by using a weighting function W to obtain a result image CORImp containing no metal artifact, but information of area near the metal artifact.

First claim

1 . A method for processing metal artifacts in a CT image, the method comprising:
performing a first metal artifact processing on an original image to obtain a first processed image COR1, wherein the original image is a reconstructed CT image based on scan data obtained by CT scanning a subject, and wherein the original image contains metal artifacts, and in the process of the first metal artifact processing, the scan data involving the metal artifacts is corrected; extracting the high frequency portion of the first processed image COR1 to obtain a first high-frequency image COR1HF; performing a second metal artifact processing on the original image to obtain a second processed image COR2, wherein in the second metal artifact processing, the metal artifacts are removed without affecting the tissue information of the subject; extracting the high frequency portion of the processed image COR2 second to obtain a second high-frequency image COR2HF; extracting a metal image from the original image and obtaining a weighting function W based on the metal image; and performing a weighted combination for the first processed image COR1, the first high-frequency image COR1HF and the second high-frequency image COR2HF by using the weighting function W to obtain a result image CORImp.

2 . The method of claim 1 , wherein the weighted combination is performed according to the following equation: CORImp=COR1+(COR2HF−COR1HF)*W.

3 . The method of claim 1 , wherein the metal artifacts include hardening artifacts and the second metal artifact processing comprises:
applying a hardening correction to the original image to reduce the hardening artifacts in the original image and to obtain the second processed image COR2.

4 . The method of claim 3 , wherein the hardening correction comprises:
smoothing filtering the original image to obtain an Ori-Smo image; smoothing filtering the first processed image COR1 to obtain a COR1-Smo image; calculating the difference between the Ori-Smo image and the COR1-Smo image to obtain an image HardenArti containing hardening artifacts; and calculating the difference between the original image and the image HardenArti to obtain the second processed image COR2.

5 . The method of claim 1 , wherein the metal artifacts include strip artifacts and hardening artifacts and the second metal artifact processing comprises:
pre-processing scan data corresponding to the original image to reduce the strip artifacts in the original image and to obtain an Ori-Air image; and applying a hardening correction to the Ori-Air image to reduce the hardening artifacts in the Ori-Air image and to obtain the second processed image COR2.

6 . The method of claim 5 , wherein the hardening correction comprises:
smoothing filtering the Ori-Air image to obtain an Ori-Air-Smo image; smoothing filtering the first processed image COR1 to obtain a COR1-Smo image; calculating the difference between the Ori-Air-Smo image and the COR1-Smo image to obtain an image HardenArti containing only hardening artifacts; and calculating the difference between the Ori-Air image and the image HardenArti to obtain the second processed image COR2.

7 . The method of claim 1 , wherein obtaining a weighting function W based on the metal image Metal comprises:
applying low-pass filtering to the metal image Metal to obtain a low-frequency metal image; and normalizing the low-frequency metal image to obtain the weighting function W.

8 . A device for processing metal artifacts in a CT image, the device comprising:
a processor which invokes machine readable instructions corresponding to a control logic for processing metal artifacts in a CT image stored on a storage medium and executes the machine readable instructions to:
perform a first metal artifact processing on an original image to obtain a first processed image COR1, wherein the original image is a reconstructed CT image based on scan data obtained by CT scanning a subject, and wherein the original image contains metal artifacts, and in the process of the first metal artifact processing, the scan data involving the metal artifacts is corrected;
extract the high frequency portion of the first processed image COR1 to obtain a first high-frequency image COR1HF;
perform a second metal artifact processing on the original image to obtain a second processed image COR2, wherein in the second metal artifact processing, the metal artifacts are removed without affecting the tissue information of the subject;
extract the high frequency portion of the processed image COR2 second to obtain a second high-frequency image COR2HF;
extract a metal image Metal from the original image and obtaining a weighting function W based on the metal image Metal; and
perform a weighted combination for the first processed image COR1, the first high-frequency image COR1HF and the second high-frequency image COR2HF by using the weighting function W to obtain a result image CORImp.

9 . The device according to claim 8 , wherein the weighted combination is performed according to the following equation: CORImp=COR1+(COR2HF−COR1HF)*W.

10 . The device according to claim 8 , wherein the metal artifacts include hardening artifacts and said machine readable instructions further cause the processor to:
apply a hardening correction to the original image to reduce the hardening artifacts in the original image and to obtain the second processed image COR2.

11 . The device according to claim 10 , wherein said machine readable instructions further cause the processor to:
smoothing filter the original image to obtain an Ori-Smo image; smoothing filter the first processed image COR1 to obtain a COR1-Smo image; calculate the difference between the Ori-Smo image and the COR1-Smo image to obtain an image HardenArti containing hardening artifacts; and calculate the difference between the original image and the image HardenArti to obtain the second processed image COR2.

12 . The device according to claim 8 , wherein the metal artifacts include strip artifacts and hardening artifacts and said machine readable instructions further cause the processor to:
pre-process scan data corresponding to the original image to reduce the strip artifacts in the original image and to obtain an Ori-Air image; and apply a hardening correction to the Ori-Air image to reduce the hardening artifacts in the Ori-Air image and to obtain the second processed image COR2.

13 . The device according to claim 12 , wherein said machine readable instructions further cause the processor to:
smoothing filter the Ori-Air image to obtain an Ori-Air-Smo image; smoothing filter the first processed image COR1 to obtain a COR1-Smo image; calculate the difference between the Ori-Air-Smo image and the COR1-Smo image to obtain an image HardenArti containing hardening artifacts; and calculate the difference between the Ori-Air image and the image HardenArti to obtain the second processed image COR2.

14 . The device according to claim 8 , wherein said machine readable instructions further cause the processor to:
apply low-pass filtering to the metal image to obtain a low-frequency metal image; and normalize the low-frequency metal image to obtain the weighting function W.

Assignees

• Shenyang Neusoft Medical Sys

Inventors

• Han Junlong
• Pang Ling
• Lou Shanshan

Classifications

• G06T12/30 Primary

  Image post-processing, e.g. metal artefact correction · CPC title

• G06T11/60

  Creating or editing images; Combining images with text · CPC title

• G06T11/003 Primary

  Physics · mapped topic

• G06T2207/10004

  Still image; Photographic image · CPC title

• G06T2207/10081

  Computed x-ray tomography [CT] · CPC title