Method and apparatus for motion correction in CT imaging

Patent metadata

Field	Value
Publication number	US-10722178-B2
Application number	US-201715608666-A
Country	US
Kind code	B2
Filing date	May 30, 2017
Priority date	May 30, 2016
Publication date	Jul 28, 2020
Grant date	Jul 28, 2020

Abstract

A method for the reduction of motion artifacts in CT imaging, the method including the steps of: (a) reconstructing from the raw CT data an initial estimate of the object of interest; (b) estimating the pose of the object at each projection angle; (c) undertaking a motion-corrected reconstruction from the measured projections, accounting for the pose changes estimated in (b) by employing a modified source/detector orbit that accounts for the object motion; (d) iterating steps (b)-(c) until a predetermined convergence criterion is met; and (e) making a final reconstruction of the required image size using the pose estimates obtained in the previous steps.

First claim

What is claimed is:

1. A method for a reduction of motion artifacts in computed tomography (CT) reconstruction imagery, the method including the steps of:
(a) reconstructing, from a CT data set comprising measured projections acquired by a detector at a plurality of angles around an object of interest, an initial estimate of a 3D attenuation distribution of the object of interest;
(b) at each angle of the CT data set, a forward projection of the estimated 3D attenuation distribution within the object of interest and the CT projection measured at the same projection at the same angle are used to estimate a pose of the object of interest;
(c) undertaking a further reconstruction from the measured projections, accounting for a pose changes between two successive pose estimates from (b) to produce a motion corrected estimate of the 3D attenuation distribution;
(d) iterating steps (b)-(c) until the pose estimates obtained at all angles in two successive iterations differ by less than a predetermined convergence criterion; and
(e) producing a final image reconstruction of a desired image size using a final pose estimates obtained at an end of step (d).

2. The method as claimed in claim 1 , wherein said steps (b) and (c) include the minimization of a cost function including a summation of differences between the measured projections and the corresponding forward projections of the motion corrected estimate of the 3d attenuation distribution at all projection angles.

3. The method as claimed in claim 1 , further comprising performing the method across multiple resolutions of the CT data set and image by increasing a sampling of the CT data with further iterations of steps (b) to (c).

4. The method as claimed in claim 3 , wherein the multiple resolutions provide an increasing resolution for successive estimates of the 3D attenuation distribution.

5. The method as claimed in claim 1 , wherein the pose includes three dimensional rotation and translation of the object of interest.

6. A method according to claim 5 , wherein a coordinate system for the pose is with respect to the detector.

7. The method as claimed in claim 6 , wherein one of said translations is perpendicular to the detector and the perpendicular translation is neglected in the pose estimate.

8. The method as claimed in claim 1 , wherein said step (c) includes applying an ordered subset expectation maximization (OSEM) image reconstruction algorithm to the measured projections of the CT data, making use of the pose changes to estimate an arbitrary orbit used in the OSEM.

9. A method according to claim 1 , wherein the computed tomography (CT) includes at least one of helical CT, circular orbit CT, cone beam CT and dental CT.

10. A method according to claim 1 , wherein said step (c) includes applying an image reconstruction algorithm that makes use of the pose changes to estimate a modified orbit to obtain a motion corrected image reconstruction from the measured CT projections, or applying an ordered subset expectation maximization (OSEM) that makes use of the pose changes to estimate a modified orbit to obtain a motion corrected image reconstruction from the measured CT projections.

Assignees

• Western Sydney Local Health Distr
• Univ Sydney
• Univ Leuven Kath

Inventors

• Fulton Roger
• Nuyts Johan
• Sun Tao
• Kim Jung-Ha

Classifications

• G06T12/30

  Image post-processing, e.g. metal artefact correction · CPC title

• G06T12/00

  Tomographic reconstruction from projections · CPC title

• A61B6/027

  characterised by the use of a particular data acquisition trajectory, e.g. helical or spiral · CPC title

• A61B5/721 Primary

  using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured · CPC title

• G06F3/04847 Primary

  Interaction techniques to control parameter settings, e.g. interaction with sliders or dials · CPC title