Method for removing streak from detector cell with performance difference

Patent metadata

Field	Value
Publication number	US-10217248-B2
Application number	US-201515507077-A
Country	US
Kind code	B2
Filing date	Jul 31, 2015
Priority date	Aug 27, 2014
Publication date	Feb 26, 2019
Grant date	Feb 26, 2019

Abstract

Embodiments of the present invention disclose a method for removing streaks from detector cells with performance difference, specifically a method for removing streaks from detector cells with performance difference and streaks caused by other reasons. The method comprises: estimating a projection on a detector cell with performance difference for each of one or more views; reconstructing one or more initial images with the estimated projection on the detector cell with performance difference for each view; estimating a projection error on the detector cell with performance difference for each view from the reconstructed one or more initial images having streaks; and reconstructing one or more output images with the estimated projection error on the detector cell with performance difference for each view to remove the streaks from the reconstructed one or more output images, improving quality of CT reconstructed images.

First claim

We claim:

1. A method for removing streaks from detector cells with performance difference, comprising the steps of:
estimating a projection on a detector cell with performance difference for each of one or more views;
reconstructing one or more initial images with the estimated projection on the detector cell with performance difference for each view;
estimating a projection error on the detector cell with performance difference for each view from the reconstructed one or more initial images having streaks; and
reconstructing one or more output images with the estimated projection error on the detector cell with performance difference for each view to remove the streaks from the reconstructed one or more output images.

2. The method of claim 1 , wherein the step of estimating a projection on a detector cell comprises estimating a projection on a detector cell with performance difference using an interpolation method.

3. The method of claim 1 , wherein the step of reconstructing one or more output images comprises:
subtracting the estimated projection error on the detector cell with performance difference from the estimated projection on the detector cell with performance difference to obtain a corrected projection on the detector cell with performance difference; and
reconstructing one or more output images with the corrected projection on the detector cell with performance difference.

4. The method of claim 3 , wherein the step of reconstructing one or more initial images comprises reconstructing one or more initial images with the estimated projection on the detector cell with performance difference using a filter backprojection method, and the step of reconstructing one or more output images comprises reconstructing one or more output images with the estimated projection error on the detector cell with performance difference error using a filter backprojection method.

5. The method of claim 4 , wherein the step of estimating a projection error on the detector cell comprises:
extracting an image stripe along a projection ray of the detector cell with performance difference from the reconstructed one or more initial images; and
estimating the projection error on the detector cell with performance difference using one or more gray values of one or more pixels in the extracted image stripe.

6. The method of claim 5 , wherein the step of estimating a projection error on the detector cell further comprises:
forming a first straight line between a position of an X-ray source and a position of the detector cell with performance difference;
selecting second and third straight lines parallel to the first straight line, wherein a distance from the second straight line to the first straight line is the same as a distance from the third straight line to the first straight line; and
estimating the projection error on the detector cell with performance difference using one or more gray values of one or more corresponding pixels of the first, the second and the third straight lines.

7. The method of claim 6 , wherein the step of estimating a projection error on the detector cell further comprises:
dividing the first straight line into M segments;
dividing respectively the second and the third straight lines into corresponding M segments as well; and
computing the projection error on the detector cell with performance difference using the following equation:

p
e

⁡

(

n
,
row
,
view

)

=

e

-

(

a
M

)

2

⁢

C
1

⁢

∑

k
=
1

M

⁢

I
s

⁡

(

k
,
2

)

-

I
s

⁡

(

k
,
1

)

+

I
s

⁡

(

k
,
3

)

2

M

wherein p e (n,row,view) represents the projection error on the detector cell with performance difference, I s (k,2) represents a gray value of the k th segment on the first straight line, I s (k,1) represents a gray value of the k th segment on the second straight line, I s (k,3) represents a gray value of the k th segment on the third straight line, M represents the number of the segments divided, C 1 represents a constant mapping a streak level to the projection error on the detector cell with performance difference, and a represents the number of non-zero elements in I s ( k ,2), wherein

I
s

⁡

(

k
_

,
2

)

=

I
s

⁡

Assignees

• Gen Electric

Inventors

• Yan Ming
• Tao Kun
• Xu Hao

Classifications

• G06T12/10 Primary

  Image preprocessing, e.g. calibration, positioning of sources or scatter correction · CPC title

• G06T2207/10081

  Computed x-ray tomography [CT] · CPC title

• G06T7/0012

  Biomedical image inspection · CPC title

• A61B6/5205

  involving processing of raw data to produce diagnostic data · CPC title

• A61B6/032

  Transmission computed tomography [CT] · CPC title