Method and apparatus for 3D metal and high-density artifact correction for cone-beam and fan-beam CT imaging
A 3D metal artifacts correction technique corrects the streaking artifacts generated by titanium implants or other similar objects. A cone-beam computed tomography system is utilized to provide 3D images. A priori information (such as the shape information and the CT value) of high density sub-objects is acquired and used for later artifacts correction. An optimization process with iterations is applied to minimize the error and result in accurate reconstruction images of the object.
1. A method for producing an image of a region of interest while correcting artifacts caused by sub-objects within the region of interest, the method comprising:
(a) receiving three-dimensional image data of the region of interest;
(b) receiving a library of shape information and imaging characteristics of the sub-objects;
(c) using the three-dimensional image data and the library to produce images of the sub-objects in the region of interest;
(d) using an optimization process to produce segmented images of the sub-objects in the region of interest;
(e) using the segmented images to produce error projections; and
(f) using the error projections to produce the projection images of the region of interest such that the artifacts are corrected in the image;
(g) performing a tomographically reconstructed image of the region of interest from the corrected projection images.
2. The method of claim 1 , wherein the three-dimensional image data comprise computed tomography image data.
3. The method of claim 2 , wherein the computed tomography image data are cone-beam or fan-beam computed tomography image data.
4. The method of claim 1 , wherein step (a) comprises taking the three-dimensional image data.
5. The method of claim 1 , wherein step (a) comprises receiving the three-dimensional image data previously formed on a storage medium or over a communication medium.
6. The method of claim 1 , wherein step (b) comprises receiving the library previously formed on a storage medium.
7. The method of claim 1 , wherein step (b) comprises forming the library through scanning, reconstruction and information extraction performed on the sub-objects.
8. The method of claim 1 , wherein step (e) comprises determining an amount of beam hardening caused by the sub-objects.
9. The method of claim 8 , wherein step (e) further comprises calculating a polynomial function of a line integral of the beam hardening.
10. The method of claim 1 , wherein the sub-objects comprise metal objects causing metal artifacts in the images.
11. The method of claim 1 , wherein the optimization process is iterative.
12. A system for producing an image of a region of interest while correcting artifacts caused by sub-objects within the region of interest, the system comprising:
a device for receiving three-dimensional image data of the region of interest;
a device for receiving a library of shape information and imaging characteristics of the sub-objects;
a processor, having access to the three-dimensional image data and the library, the processor being configured for:
(i) using the three-dimensional image data and the library to produce images of the sub-objects in the region of interest;
(ii) performing an optimization process to produce segmented images of the sub-objects in the region of interest;
(iii) using the segmented images to produce error projections; and
(iv) using the error projections to produce the projection images of the region of interest such that the artifacts are corrected in the projection images; and
(v) obtaining tomographically-reconstructed image of the region of interest from the corrected projection images
an output for outputting the reconstructed image of the region of interest.
13. The system of claim 12 , wherein the processor is configured such that the three-dimensional image data comprise computed tomography image data.
14. The system of claim 13 , wherein the processor is configured such that the computed tomography image data are cone-beam or fan-beam computed tomography image data.
15. The system of claim 12 , wherein the device for receiving the three-dimensional image data comprises a device for taking the three-dimensional image data.
16. The system of claim 12 , wherein the device for receiving the three-dimensional image data comprises a device for receiving the three-dimensional image data previously formed on a storage medium or over a communication medium.
17. The system of claim 12 , wherein the device for receiving the library comprises a device for receiving the library previously formed and provided on a storage medium.
18. The system of claim 14 , wherein the processor is configured to determine an amount of beam hardening caused by the sub-objects.
19. The system of claim 18 , wherein the processor is further configured to calculate a polynomial function of a line integral of the beam hardening.