Tomographic reconstruction of small objects using a priori knowledge

• US 6,697,508 B2
• Filed: 05/10/2002
• Issued: 02/24/2004
• Est. Priority Date: 05/10/2002
• Status: Active Grant

• Current Assignee: VisionGate, Inc.
• Original Assignee: VisionGate, Inc.
• Inventors: Nelson, Alan C.
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): SHERALI, ISHRAT I
• Application Number:
  US10/143,064
• Publication Number:
  US 20030210814A1
• Time in Patent Office: 655 Days
• Field of Search: 382/128-134, 382/154, 382/255, 382/108, 382/209, 382/216, 378/4-15, 378/21-27, 378/204-206, 378/41, 378/98-- 9, 348/295, 348/42, 348/45, 348/65, 348/67, 702/35, 435/6, 435/7.2, 600/410-430, 359/371, 359/212, 204/452, 204/603, 356/340, 356/318, 356/326, 356/73, 356/39, 356/72, 250/201.3, 250/461.2, 250/459.1
• US Class Current: 382/131
• 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

Three-dimensional (3D) reconstruction of a cell includes adjusting a current set of projection images according to a priori knowledge to produce adjusted projection images, for example, based on probability masks and/or Bayesian analysis of multiple similar objects in the same sample. A reconstruction algorithm processes the adjusted projection images to generate a 3D image. The 3D image is further adjusted according to the a priori knowledge to generate an adjusted 3D image. Criteria for process completion are applied to determine whether the adjusted 3D image is adequate. Otherwise, a set of pseudo projections are computationally created at the same projection angles as the current set of projection images and then compared to the current set of projection images to produce a set of new projections, wherein the new projections are input again to the reconstruction algorithm and the steps of the method are repeated until the adequacy criteria are met.

Claims

1. A method for tomographic three-dimensional (3D) reconstruction of a sample including at least one object of interest, the method comprising the steps of:

(a) obtaining a current set of projection images from a projection system;

(b) adjusting the current set of projection images of the sample according to a priori knowledge to produce adjusted projection images;

(c) using a reconstruction algorithm on the adjusted projection images to generate a 3D image;

(d) further adjusting the 3D image according to the a priori knowledge to generate an adjusted 3D image;

(e) applying criteria for process completion to determine whether the adjusted 3D image is adequate; and

(f) if the adjusted 3D image is not adequate, then computationally creating a set of pseudo projections at the same projection angles as the current set of projection images and comparing the current set of projection images with the pseudo projection images to produce a set of new projections, wherein the new projections are input again at step (a) as a current set of projection images and steps (a) through (e) are repeated until the adequacy criteria are met.

2. The method of claim 1, wherein the at least one object of interest comprises at least one cell.

3. The method of claim 1, wherein the step of adjusting a current set of projection images is based on a probability mask.

4. The method of claim 1, wherein the step of adjusting a current set of projection images is based on Bayesian analysis of multiple similar objects in the sample.

5. The method of claim 1, wherein the a priori knowledge includes a priori knowledge selected from the group consisting of cell preparation chemistry, contrast agents having known distributions in contrast, a measured modulation transfer function of the projection system and errors flowing from a 3D image reconstruction algorithm propagated and created in a known manner.

6. The method of claim 5 wherein the known distributions combine multiplicatively into the current set of projection images to provide a means to assess a confidence level of a particular pixel in the context of surrounding pixels.

7. The method of claim 1, wherein a projection image includes a plurality of pixels, the method further comprising the step of assigning confidence levels based on the gray value, location and context of each pixel.

8. The method of claim 7, wherein an adjusted projection image includes a plurality of adjusted pixels, further comprising the step of assigning confidence levels based on the gray value, location and context of each adjusted pixel.

9. The method of claim 1, wherein the 3D image includes a plurality of voxels, further comprising the step of assigning confidence levels based on the gray value, location and context of each voxel.

10. The method of claim 9, wherein the adjusted 3D image includes a plurality of adjusted voxels, further comprising the step of assigning confidence levels based on the gray value, location and context of each adjusted voxel.

11. A system for tomographic three-dimensional (3D) reconstruction of an object of interest in a sample, comprising:

(a) a projection system for generating a current set of projection images from the sample;

(b) means, coupled to receive the current set of projection images, for adjusting the current set of projection images of the sample according to a priori knowledge to produce adjusted projection images;

(c) means, coupled to receive the adjusted projection images, for using a reconstruction algorithm on the adjusted projection images to generate a 3D image;

(d) means, coupled to receive the 3D image, for further adjusting the 3D image according to the a priori knowledge to generate an adjusted 3D image;

(e) means, coupled to receive the adjusted 3D image, for applying criteria for process completion to determine whether the adjusted 3D image is adequate; and

(f) means, coupled to receive the adjusted 3D image if not adequate, for otherwise computationally creating a set of pseudo projections at the same projection angles as the current set of projection images and comparing the current set of projection images with the pseudo projection images to generate a set of new projections, wherein the new projections are input again to the means for adjusting a current set of projection images as a current set of projection images.

12. The system of claim 11, wherein the object of interest is a cell.

13. The system of claim 11, wherein the means for adjusting a current set of projection images is based on a probability mask.

14. The system of claim 11, wherein the means for adjusting a current set of projection images is based on Bayesian analysis of multiple similar objects in the same sample.

15. The system of claim 11, wherein the a priori knowledge including a priori knowledge selected from the group consisting of cell preparation chemistry knowledge, knowledge of contrast agents having known distributions in contrast, a measured modulation transfer function of the projection system and knowledge of errors flowing from a 3D image reconstruction algorithm propagated and created in a known manner.

16. The system of claim 15 wherein the known distributions combine multiplicatively into the current set of projection images to provide a means to assess the confidence level of a particular pixel in the context of surrounding pixels.

17. The system of claim 11, wherein each projection image includes a plurality of pixels, the system further comprising means for assigning confidence levels based on gray value, location and context of each pixel.

18. The system of claim 17, wherein each adjusted projection image includes a plurality of adjusted pixels, the system further comprising means for assigning confidence levels based on gray value, location and context of each adjusted pixel.

19. The system of claim 17, wherein the 3D image includes a plurality of voxels, the system further comprising means for assigning confidence levels based on gray value, location and context of each voxel.

20. The system of claim 19, wherein the 3D image includes a plurality of adjusted voxels, further comprising means for assigning confidence levels based on the gray value, location and context of each adjusted voxel in a projection image.

21. A method for tomographic three-dimensional (3D) reconstruction from a set of projection images from a sample processed in a projection system including at least one cell, comprising the steps of:

(a) adjusting a current set of projection images of the sample according to a first set of a priori knowledge to produce adjusted projection images, based on Bayesian analysis of multiple similar objects in the sample;

(b) using a reconstruction algorithm on the adjusted projection images to generate a 3D image based on Bayesian analysis of multiple similar objects in the sample;

(c) further adjusting the 3D image according to a second set of a priori knowledge to generate an adjusted 3D image based on Bayesian analysis of multiple similar objects in the sample;

(d) applying criteria for process completion to determine whether the adjusted 3D image is adequate; and

(e) if the adjusted 3D image is not adequate, then computationally creating a set of pseudo projections at the same projection angles as the current set of projection images and comparing the current set of projection images with the pseudo projection images to produce a set of new projections, wherein the new projections are input again to the reconstruction algorithm at step (a) as a current set of projection images and steps (a) through (e) are repeated until the adequacy criteria are met.

22. The method of claim 21, wherein the second set of a priori knowledge includes a priori knowledge selected from the group consisting of cell preparation chemistry, contrast agents having known distributions in contrast, a measured modulation transfer function of the projection system and errors flowing from a 3D image reconstruction algorithm propagated and created in a known manner.