X-ray dual-energy CT reconstruction method

Patent metadata

Field	Value
Publication number	US-9513235-B2
Application number	US-201414337209-A
Country	US
Kind code	B2
Filing date	Jul 22, 2014
Priority date	Jul 26, 2013
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

The present disclosure relates to a self-prior information based X-ray dual-energy CT reconstruction method, which can utilize information inherent in data to provide a prior model, thereby obtaining a reconstructed image with a high quality. The X-ray dual-energy CT reconstruction method according to the present disclosure comprises: (a) rating an energy spectrum and establishing a dual-energy lookup table; (b) collecting high-energy data p H and low-energy data p L of a dual-energy CT imaging system using a detector of the dual-energy CT imaging system; (c) obtaining projection images R 1 and R 2 of scaled images r 1 and r 2 according to the obtained high-energy data p H and low-energy data p L ; (d) reconstructing the scaled image r 2 using a first piece-wise smooth constraint condition and thereby obtaining an electron density image; and (e) reconstructing the scaled image r 1 using a second piece-wise smooth constraint condition and thereby obtaining an equivalent atomic number image. In the present disclosure, the noise in the dual-energy reconstructed image can be effectively prohibited while keeping the resolution by effectively using information inherent in data.

First claim

What is claimed is:

1. An X-ray dual-energy CT reconstruction method, comprising:
(a) collecting high-energy data p H and low-energy data p L of a dual-energy CT imaging system using a detector of the dual-energy CT imaging system;
(b) obtaining projection images R 1 and R 2 of scaled images r 1 and r 2 according to the obtained high-energy data p H and low-energy data p L ;
(c) reconstructing the scaled image r 2 using a first piece-wise smooth constraint condition and obtaining a decomposition coefficient a 2 ; and
(d) reconstructing the scaled image r 1 using a second piece-wise smooth constraint condition and obtaining a decomposition coefficient a 1 .

2. The X-ray dual-energy CT reconstruction method according to claim 1 , wherein, the scaled images r 1 and r 2 are defined in equation (4) as follows:

r
1

≡

diag
⁡

(

1

ω
1

+
ɛ

)

⁢

a
1

⁢

⁢

r
2

≡

diag
⁡

(

1

ω
2

+
ɛ

)

⁢

a
2

(
4
)

the projection images R 1 and R 2 are defined in equation (6) as follows:
R 1 ≡H′ 1 r 1
R 2 ≡H′ 2 r 2   (6)

wherein, H′ 1 ≡Hdiag(ω 1 +ε) and H′ 2 ≡Hdiag(ω 2 +ε), in which H is a projection matrix, a 1 and a 2 are decomposition coefficients, ε is a vector with small constant coefficients, and ω 1 and ω 2 are vectors which can be selected randomly,
in the step (c), r 2 is reconstructed using the following equation (9) as the first piece-wise smooth constraint condition:

min

r
2

⁢



∇

r
2



p

⁢

⁢

s
.
t
.

⁢

R
2

≡

H
2
′

⁢

r
2

(
9
)

and in the step (d), r 1 is reconstructed using the following equation (8) as the second piece-wise smooth constraint condition:

min

r
1

⁢



∇

r
1



p

⁢

⁢

s
.
t
.

⁢

R
1

≡

H
1
′

⁢

r
1

.

(
8
)

3. The X-

Assignees

• Univ Tsinghua
• Nuctech Co Ltd

Inventors

• Xing Yuxiang
• Shen Le
• Zhang Li
• Chen Zhiqiang
• Li Liang

Classifications

• G06T12/20 Primary

  Inverse problem, i.e. transformations from projection space into object space · CPC title

• G06T2207/10081

  Computed x-ray tomography [CT] · CPC title

• G06T2211/408

  Dual energy · CPC title

• G06T2207/30004

  Biomedical image processing · CPC title

• G01N23/046 Primary

  using tomography, e.g. computed tomography [CT] · CPC title