Method and apparatus of global de-noising for cone beam and fan beam CT imaging

1. A method for producing a globally de-noised cone beam 3D image of an object, the method comprising:

(a) taking raw cone beam tomography projection image data from the object:

(b) applying a wavelet domain denoising technique to the image data;

(c) applying at least one other denoising technique to the image data, wherein said at least one other denoising technique comprises a Fourier-transform-based denoising technique;

(d) performing a reconstruction to provide feedback to the wavelet domain denoising technique and the at least one other denoising technique; and

(e) reconstructing the final image from the denoised projection image data to achieve global denoising.

2. The method of claim 1 , wherein said at least one other denoising technique comprises at least one other denoising technique in the projection domain.

3. The method of claim 2 , wherein said at least one other denoising technique in the projection domain further comprises a digital reconstruction filter-based denoising technique.

4. The method of claim 1 , further comprising applying a denoising technique in the reconstruction domain.

5. The method of claim 1 , wherein step (d) comprises:

(i) measuring a quantity in the reconstructed image which represents a quality of the reconstructed image;

(ii) comparing the quantity to a required value of the quantity; and

(iii) using a result of step (d)(ii) to provide a feedback to at least one of steps (a)-(c).

6. The method of claim 5 , wherein the at least one quantity comprises a contrast to noise ratio.

7. A system for producing a de-noised image of a region of interest, the system comprising:

a source of radiation providing cone beam radiation to be made incident on the region of interest;

a detector for detecting the radiation after the radiation has been made incident on the region of interest and for outputting raw cone beam tomography projection image data; and

a processing device, in electronic communication with the detector, configured to perform the steps of:

(a) taking the raw cone beam tomography projection image data from the object:

(b) applying a wavelet domain denoising technique to the image data;

(c) applying at least one other denoising technique to the image data,

wherein said at least one other denoising technique comprises a Fourier-transform-based denoising technique;

(d) performing a reconstruction to provide feedback to the wavelet domain denoising technique and the at least one other denoising technique; and

(e) reconstructing the final image from the denoised projection image data to achieve global denoising.

8. The system of claim 7 , wherein said at least one other denoising technique comprises at least one other denoising technique in the projection domain.

9. The system of claim 8 , wherein said at least one other denoising technique in the projection domain further comprises a digital reconstruction filter-based denoising technique.

10. The system of claim 7 , wherein the processing device further applies a denoising technique in the reconstruction domain.

11. The system of claim 7 , wherein the processing device performs step (d) by:

(i) measuring a quantity in the reconstructed image which represents a quality of the reconstructed image;

(ii) comparing the quantity to a required value of the quantity; and

(iii) using a result of step (d)(ii) to provide a feedback when the processing device performs at least one of steps (a)-(c).

12. The system of claim 11 , wherein the at least one quantity comprises a carrier to noise ratio.

13. The system of claim 7 , wherein the source comprises a source of X-rays.

14. The system of claim 7 , wherein the detector comprises a two-dimensional detector.

15. The system of claim 14 , wherein the two-dimensional detector is a flat-panel detector.