System and methods for tomography image reconstruction

• US 20080247502A1
• Filed: 04/05/2007
• Published: 10/09/2008
• Est. Priority Date: 04/05/2007
• Status: Active Grant

• Current Assignee: University of Minnesota
• Original Assignee: University of Minnesota
• Inventors: Liao, Hstau Y.
• Granted Patent: US 7,840,053 B2
• Time in Patent Office: Days
• US Class Current: 378/4
• CPC Class Codes: A61B 6/027 characterised by the use of a particular data acquisition trajectory, e.g. helical or spiral
• CPC Class Codes: G01N 2223/419 computed tomograph
• CPC Class Codes: G01N 23/046 using tomography, e.g. computed tomography [CT]
• CPC Class Codes: G06T 11/006 Inverse problem, transformation from projection-space into object-space, e.g. transform methods, back-projection, algebraic methods
• CPC Class Codes: G06T 2211/424 Iterative

Abstract

The present invention is a tomographic reconstruction algorithm, which is highly effective improving image quality and accuracy by reducing or eliminating artifacts within images produced by limited data tomography. Using algebraic reconstruction techniques (ART), depending on whether or not an object has higher or lower densities, a current threshold value is set to either a high or low threshold parameter and then decreased or increased, respectively, to reduce or eliminate the artifacts in a reconstructed image.

Claims

1. A method to reduce artifacts in limited data tomography, comprising:

(a) providing an algebraic reconstruction technique algorithm including at least two iterative steps;

(b) establishing a high threshold parameter and a low threshold parameter;

(c) setting a current threshold value of a transformation equal to the high threshold parameter;

(d) applying one iterative step of the algebraic reconstruction technique algorithm resulting in reconstructive values;

(e) determining if the reconstructive values of the algebraic reconstruction technique algorithm are less than the current threshold value of the transformation;

(f) changing the reconstructive values to equal the current threshold value of the transformation;

(g) decreasing the current threshold value of the transformation slightly toward the low threshold parameter;

(h) repeating the steps (d) through (g) until the current threshold value of the transformation reaches below the low threshold parameter; and

(i) displaying the reconstructive values as an image.

2. The method of claim 1, further comprising the step (j) using the reconstructive values to establish a high threshold parameter and a low threshold parameter;

3. The method of claim 2, further comprising the step (k) rerunning the steps (c) through (i).

4. A method to reduce artifacts in limited data tomography, comprising:

(a) providing an algebraic reconstruction technique algorithm including at least two iterative steps;

(b) establishing a high threshold parameter and a low threshold parameter;

(c) setting a current threshold value of a transformation equal to the low threshold parameter;

(d) applying one iterative step of the algebraic reconstruction technique algorithm resulting in reconstructive values;

(e) determining if the reconstructive values of the algebraic reconstruction technique algorithm are greater than the current threshold value of the transformation;

(f) changing the reconstructive values to equal the current threshold value of the transformation;

(g) increasing the current threshold value of the transformation slightly toward the high threshold parameter;

(h) repeating the steps (d) through (g) until the current threshold value of the transformation reaches above the high threshold parameter; and

(i) displaying the reconstructive values as an image.

5. The method of claim 4, further comprising the step (j) using the reconstructive values to establish a high threshold parameter and a low threshold parameter.

6. The method of claim 5, further comprising the step (k) rerunning the steps (c) through (i).

7. A system to reduce artifacts in limited data tomography, comprising:

a computer including a computer processor with a plurality of components, wherein said computer processor includes an algebraic reconstruction technique algorithm including at least two iterative steps;

a first computer processor component to establish a high threshold parameter and a low threshold parameter, wherein said first computer processor component sets a current threshold value of a transformation equal to said high threshold parameter;

a second computer processor component to apply one iterative step of said algebraic reconstruction technique algorithm resulting in reconstructive values, wherein said second computer processor component determines if said reconstructive values of said algebraic reconstruction technique algorithm are less than said current threshold value of said transformation;

a third computer processor component to change said reconstructive values to equal said current threshold value of said transformation, wherein said third computer processor component decreases said current threshold value of said transformation slightly toward said low threshold parameter;

a fourth computer processor component to monitor said transformation until said current threshold value of said transformation reaches below the low threshold parameter; and

a display to illustrate said reconstructive values as an image.

8. The system of claim 7, wherein said reconstructive values establish said high threshold parameter and said low threshold parameter.

9. The system of claim 8, wherein said computer processor repeats said transformation.

10. A system to reduce artifacts in limited data tomography, comprising:

a computer including a computer processor with a plurality of components, wherein said computer processor includes an algebraic reconstruction technique algorithm including at least two iterative steps;

a first computer processor component to establish a high threshold parameter and a low threshold parameter, wherein said first computer processor component sets a current threshold value of a transformation equal to said low threshold parameter;

a second computer processor component to apply one iterative step of said algebraic reconstruction technique algorithm resulting in reconstructive values, wherein said second computer processor component determines if said reconstructive values of said algebraic reconstruction technique algorithm are greater than said current threshold value of said transformation;

a third computer processor component to change said reconstructive values to equal said current threshold value of said transformation, wherein said third computer processor component increases said current threshold value of said transformation slightly toward said low threshold parameter;

a fourth computer processor component to monitor said transformation until said current threshold value of said transformation above said high threshold parameter; and

a display to illustrate said reconstructive values as an image.

11. The system of claim 10, wherein said reconstructive values establish said high threshold parameter and said low threshold parameter.

12. The system of claim 11, wherein said computer processor repeats said transformation.