Computed tomography based on linear scanning

• US 9,730,657 B2
• Filed: 12/17/2014
• Issued: 08/15/2017
• Est. Priority Date: 12/17/2013
• Status: Active Grant

• Current Assignee: Rensselaer Polytechnic Institute
• Original Assignee: Rensselaer Polytechnic Institute
• Inventors: Liu, Fenglin, Yu, Hengyong, Wang, Ge, Cong, Wenxiang
• Primary Examiner(s): Yun, Jurie
• Application Number:
  US14/573,967
• Publication Number:
  US 20150170361A1
• Time in Patent Office: 972 Days
• Field of Search: 378 4, 378 9, 378 10, 378 11, 378 21, 378 25, 378 26, 378901
• CPC Class Codes: A61B 6/025 Tomosynthesis
• CPC Class Codes: A61B 6/027 characterised by the use of a particular data acquisition trajectory, e.g. helical or spiral
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/035 Mechanical aspects of CT
• CPC Class Codes: A61B 6/4007 characterised by using a plurality of source units
• CPC Class Codes: A61B 6/4014 arranged in multiple source-detector units
• CPC Class Codes: A61B 6/4452 the source unit and the detector unit being able to move relative to each other
• CPC Class Codes: A61B 6/5205 involving processing of raw data to produce diagnostic data
• 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 2211/432 Truncation
• CPC Class Codes: G06T 2211/436 Limited angle

Abstract

Imaging methods and imaging systems are provided. Methods and systems of the subject invention can include linearly translating a source and a detector. The source and the detector can be moved in opposite or approximately opposite directions. Acquired data can be used to reconstruct a tomographic image by using, for example, a compressive sensing technique.

Claims

1. An imaging method, comprising:

positioning an X-ray source on a first side of a subject to be imaged such that the X-ray source faces the subject;

positioning a detector on a second side of the subject such that the detector faces the subject;

linearly translating the X-ray source and the detector by simultaneously moving the X-ray source and the detector in opposite or approximately opposite directions while the X-ray source supplies X-rays and the detector acquires tomographic data of the subject; and

reconstructing a Computed Tomography (CT) image based on the tomographic data

wherein linearly translating the X-ray source and the detector is performed twice, and

wherein a first path traveled by the X-ray source during the first linear translation step is orthogonal to a second path traveled b the X-ray source during the second linear translation step.

2. The imaging method according to claim 1, wherein the subject is a human patient.

3. The imaging method according to claim 1, wherein an entire length of the first path traveled by the X-ray source during the first linear translation step is equal to an entire length of the second path traveled by the X-ray source during the second linear translation step and an entire length of a third path traveled by the X-ray source during a third linear translation step.

4. The imaging method according to claim 1, wherein reconstructing a CT image based on the tomographic data comprises:

modeling the acquired data as a linear matrix equation (b) based on a pixel basis;

modeling the CT image to be reconstructed as a linear matrix equation (X) based on a pixel basis; and

performing the following algorithm;

step 1—

input data;

b and let X=0;

step 2—

calculate the current image;

step 3—

minimize the total variation (TV) of the current image X; and

step 4—

go to step 2 until a stopping criterion is met.

5. An imaging method, comprising:

positioning an X-ray source on a first side of a subject to be imaged such that the X-ray source faces the subject;

positioning a detector on a second side of the subject such that the detector faces the subject;

linearly translating the X-ray source and the detector by simultaneously moving the X-ray source and the detector in opposite or approximately opposite directions while the X-ray source supplies X-rays and the detector acquires tomographic data of the subject; and

reconstructing a Computed Tomography (CT) image based on the tomographic data,

wherein reconstructing a CT image based on the tomographic data comprises;

modeling the acquired data as a linear matrix equation (b) based on a pixel basis;

modeling the CT image to be reconstructed as a linear matrix equation (X) based on a pixel basis; and

performing the following algorithm;

step 1—

input data;

b and let X=0

step 2—

calculate the current image;

step 3—

minimize the total variation (TV) of the current image X; and

step 4—

no to step 2 until a stopping criterion is met,

wherein step 2—

calculate the current image comprises calculating the image using the following equation;

6. The imaging method according to claim 5, wherein step 3—

minimizing the TV of the current image X comprises minimizing the TV of the current image X using the following formula;

X_n^(l+1)=X_n^(l)−

λ

ω

υ

,

where λ

is a control parameter, υ

=(∂

∥

∇

X∥

₁/∂

X_i,j)|_{Xi,j=Xi,j[k,l]} is the gradient direction with respect to X_i,j=X_i,j [k,l], ω

=max(X_n^(l))/max(|υ

|) is a scaling constant, and k and l are the outer and inner loop indices.

7. The imaging method according to claim 6, wherein the stopping criterion of step 4 is reaching a maximum number of iterations.

8. The imaging method according to claim 6, wherein linearly translating the X-ray source and the detector is performed twice, and

wherein a first path traveled by the X-ray source during the first linear translation step is orthogonal to a second path traveled by the X-ray source during the second linear translation step.

9. The imaging method according to claim 6, wherein linearly translating the X-ray source and the detector is performed three times, and

wherein an entire length of a first path traveled by the X-ray source during the first linear translation step is equal to an entire length of a second path traveled by the X-ray source during the second linear translation step and an entire length of a third path traveled by the X-ray source during the third linear translation step.

10. The imaging method according to claim 5, wherein the subject is a human patient.

11. The imaging method according to claim 5, wherein linearly translating the X-ray source and the detector is performed twice.

12. The imaging method according to claim 11, wherein a first path traveled by the X-ray source during the first linear translation step is orthogonal to a second path traveled by the X-ray source during the second linear translation step.

13. The imaging method according to claim 5, wherein linearly translating the X-ray source and the detector is performed three times.

14. The imaging method according to claim 5, wherein an entire length of a first path traveled by the X-ray source during a first linear translation step is equal to an entire length of a second path traveled by the X-ray source during a second linear translation step and an entire length of a third path traveled by the X-ray source during a third linear translation step.

15. An imaging system, comprising:

a main stage for a subject to be imaged;

a first X-ray source positioned to face the subject being imaged and configured to linearly translate while providing X-rays;

a first detector positioned to face the subject being imaged and to face the first X-ray source, and configured to linearly translate while acquiring tomographic data of the subject being imaged;

a frame comprising a first motorized linear stage and a second motorized linear stage;

a second X-ray source positioned to face the subject being imaged and configured to linearly translate while providing X-rays; and

a second detector positioned to face the subject being imaged and to face the second X-ray source, and configured to linearly translate while acquiring tomographic data of the subject being imaged,

wherein the imaging system is configured such that the first X-ray source and the first detector simultaneously move in opposite or approximately opposite directions while the first X-ray source supplies X-rays and the first detector acquires tomographic data,

wherein the first X-ray source is mounted on the first motorized linear stage,

wherein the first detector is mounted on the second motorized linear stage,

wherein the first motorized linear stage is configured to move the first X-ray source linearly,

wherein the second motorized linear stage is configured to move the first detector linearly in a direction that is opposite or approximately opposite to the direction in which the first X-ray source is moving,

wherein the imaging system is configured such that the second X-ray source and the second detector simultaneously move in opposite or approximately opposite directions while the second X-ray source supplies X-rays and the second detector acquires tomographic data,

wherein the frame further comprises a third motorized linear stage and a fourth motorized linear stage,

wherein the second X-ray source is mounted on the third motorized linear stage,

wherein the second detector is mounted on the fourth motorized linear stage,

wherein the third motorized linear stage is configured to move the second X-ray source linearly,

wherein the fourth motorized linear stage is configured to move the second detector linearly in a direction that is opposite or approximately opposite to the direction in which the second X-ray source is moving, and

wherein the main stage is configured to allow the subject to lie down while being imaged.

16. The imaging system according to claim 15, wherein the main stage is further configured to also allow the subject to stand up or sit down while being imaged.

17. The imaging system according to claim 15, wherein the first detector is a linear array or a flat panel detector (FPD).

18. The imaging system according to claim 15, further comprising a non-transitory computer-readable medium having computer-executable instructions that, when executed by a processor, performing a method comprising:

modeling acquired data as a linear matrix equation (b) based on a pixel basis;

modeling a CT image to be reconstructed as a linear matrix equation (X) based on a pixel basis; and

performing the following algorithm;

step 1—

input data;

b and let X=0;

step 2—

calculate the current image;

step 3—

minimize the total variation (TV) of the current image X; and

step 4—

go to step 2 until a stopping criterion is met,

wherein step 2—

calculate the current image comprises calculating the image using the following equation;

19. The imaging system according to claim 15, wherein each of the first detector and the second detector is a linear array or an FPD.

20. The imaging system according to claim 19, further comprising a non-transitory computer-readable medium having computer-executable instructions that, when executed by a processor, perform a method comprising:

modeling acquired data as a linear matrix equation (b) based on a pixel basis;

modeling a CT image to be reconstructed as a linear matrix equation (X) based on a pixel basis; and

performing the following algorithm;

step 1—

input data;

b and let X=0;

step 2—

calculate the current image;

step 3—

minimize the total variation (TV) of the current image X; and

step 4—

go to step 2 until a stopping criterion is met,

wherein step 2—

calculate the current image comprises calculating the image using the following equation;