Apparatus and method for computed tomography image processing

Patent metadata

Field	Value
Publication number	US-9354187-B2
Application number	US-201414538150-A
Country	US
Kind code	B2
Filing date	Nov 11, 2014
Priority date	Jan 24, 2014
Publication date	May 31, 2016
Grant date	May 31, 2016

Abstract

An apparatus and method for computed tomography image processing is provided. The apparatus includes: an X-ray detection unit that detects an X-ray beam having passed through a subject and outputs an energy value thereof; a line integral calculation unit that calculates line integral values of attenuation coefficients representing attenuation of the energy value of the X-ray beam having passed through the subject and been detected, based on the energy value; an image processing unit that reconstructs a tomogram based on the line integral values; and an image output unit that outputs the tomogram. The apparatus and method for computed tomography image processing can calculate line integral values of attenuation coefficients constituting an integrand of an X-ray projection function using the mean value theorem for integrals in order to restore an image of a subject from an X-ray beam detected in computed tomography image processing.

First claim

What is claimed is:

1. An apparatus for computed tomography image processing, comprising:
an X-ray detector that detects an X-ray beam having passed through a subject and outputs an energy value thereof;
a processor that calculates line integral values of attenuation coefficients representing attenuation of the energy value of the X-ray beam having passed through the subject and been detected, based on the energy value, and reconstructs a tomogram based on the line integral values; and
a display that displays the tomogram;
wherein the processor calculates, based on simultaneous equations obtained from a projection function of two different energy spectra and the energy value of the detected X-ray beam, line integral values of attenuation coefficients included in the projection function of the two different energy spectra and energy values satisfying the simultaneous equations;
wherein the processor calculates approximate values of the energy values satisfying the simultaneous equations based on first approximate values of the line integral values of the attenuation coefficients, and calculates second approximate values of the line integral values of the attenuation coefficients based on the approximate values of the energy values satisfying the simultaneous equations;
wherein the processor selects at least one of the lowest energy values and the highest energy values as the approximate values of the energy values satisfying the simultaneous equations, among energy values satisfying an equation in which the line integral values of the attenuation values in the simultaneous equations are replaced by the first approximate values of the line integral values of the attenuation values.

2. The apparatus for computed tomography image processing according to claim 1 , wherein initial approximate values of the energy values satisfying the simultaneous equations are mean values of energy values of the two different energy spectra, respectively.

3. The apparatus for computed tomography image processing according to claim 1 , wherein the processor calculates the line integral values of the attenuation coefficients and the approximate values of the energy values satisfying the simultaneous equations when differences between the first and second approximate values of the line integral values of the attenuation coefficients are less than or equal to preset limits.

4. The apparatus for computed tomography image processing according to claim 3 , wherein the processor replaces the first approximate values of the line integral values of the attenuation coefficients by the second approximate values of the line integral values of the attenuation coefficients, and repeats a procedure of calculating the approximate values of the energy values satisfying the simultaneous equations and the second approximate values of the line integral values of the attenuation coefficients, when the differences between the first approximate values and the second approximate values of the line integral values of the attenuation coefficients exceed the preset limits.

5. A method for computed tomography image processing, comprising:
detecting, by an X-ray detector, an X-ray beam emitted to a subject and outputting an energy value thereof;
calculating, by a processor, line integral values of attenuation coefficients representing attenuation of the energy value of the X-ray beam having passed through the subject and been detected, based on the energy value;
reconstructing, by the processor, a tomogram based on the line integral values; and
displaying, by a display, the tomogram,
wherein the processor calculates, based on simultaneous equations obtained from a projection function of two different energy spectra and the energy value of the detected X-ray beam, line integral values of attenuation coefficients included in the projection function of the two different energy spectra and energy values satisfying the simultaneous equations;
wherein calculating, by the processor, line integral values of attenuation coefficients comprises:
calculating approximate values of the energy values satisfying the simultaneous equations based on first approximate values of the line integral values of the attenuation coefficients, and
calculating second approximate values of the line integral values of the attenuation coefficients based on the approximate values of the energy values satisfying the simultaneous equations,
wherein, in calculation of the approximate values of the energy values satisfying the simultaneous equations, the processor selects at least one of the lowest energy values and the highest energy values as the approximate values of the energy values satisfying the simultaneous equations, among energy values satisfying an equation in which the line integral values of the attenuation values in the simultaneous equations are replaced by the first approximate values of the line integral values of the attenuation values.

6. The method for computed tomography image processing according to claim 5 , further comprising:
initializing, by the processor, the approximate values of the energy values satisfying the simultaneous equations as mean values of energy values of the two different energy spectra, respectively.

7. The method for computed tomography image processing according to claim 5 , wherein calculating, by the line integral calculation unit, line integral values of attenuation coefficients comprises:
calculating the line integral values of the attenuation coefficients and the approximate values of the energy values satisfying the simultaneous equations, when differences between the first and second approximate values of the line integral values of the attenuation coefficients are less than or equal to preset limits.

8. The method for computed tomography image processing according to claim 7 , wherein calculating, by the processor, line integral values of attenuation coefficients comprises:
repeating a procedure of calculating the approximate values of the energy values satisfying the simultaneous equations and the second approximate values of the line integral values of the attenuation coefficients, when the differences between the first approximate values and the second approximate values of the line integral values of the attenuation coefficients exceed the preset limits.

Assignees

• Inst Basic Science

Inventors

• Jeon Ki Wan
• Ahn Chi Young
• Kim Sung Whan

Classifications

• G06T12/10

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

• G06T12/00

  Tomographic reconstruction from projections · CPC title

• G06T11/003

  Physics · mapped topic

• G01N23/046 Primary

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

• G06T2211/408

  Dual energy · CPC title