System and method of computed tomography signal restoration via noise reduction
An imaging system includes a computer programmed to estimate noise in computed tomography (CT) imaging data, correlate the noise estimation with neighboring CT imaging data to generate a weighting estimation based on the correlation, de-noise the CT imaging data based on the noise estimation and on the weighting, and reconstruct an image using the de-noised CT imaging data.
1. An imaging system comprising a computer programmed to:
perform an air calibration step on computed tomography (CT) imaging data, wherein the CT imaging data comprises projection measurement data;
estimate noise in the projection measurement data;
correlate the noise estimation with neighboring projection measurement data to generate a weighting estimation based on the correlation;
de-noise the projection measurement data based on the noise estimation and on the weighting;
calculate a negative logarithm of the projection measurement data;
apply a mean preservation to the projection measurement data after calculating the negative logarithm; and
reconstruct an image using the de-noised projection measurement data.
2. The imaging system of claim 1 , wherein the computer is further programmed to estimate the noise based on a variance of each measurement using an x-ray count.
3. The imaging system of claim 2 , wherein the computer is further programmed to estimate the variance based on an assumed Poisson distribution.
4. The imaging system of claim 2 , wherein the computer is further programmed to correlate the noise estimation based on at least one of a view, a channel, and a row of CT imaging data in projection space.
5. The imaging system of claim 1 , wherein after the image is reconstructed, the computer is further programmed to estimate noise in image space.
6. The imaging system of claim 1 , wherein the computer is further programmed to correlate a noise estimate in a 3D image volume measured among one of a neighboring pixel or a neighboring patch of pixels.
7. The imaging system of claim 1 , wherein the imaging system is a CT system that includes:
a rotatable gantry for receiving an object to be scanned;
a generator configured to energize an x-ray source to generate x-rays; and
a detector positioned to receive the x-rays that pass through the object.
8. A method of imaging data processing, comprising:
performing an air calibration step on computed tomography (CT) imaging data, wherein the CT imaging data comprises projection measurement data;
estimating noise in the projection measurement data;
correlating the noise estimation with neighboring projection measurement data;
generating a weighting estimation based on the correlation;
de-noising the projection measurement data based on the estimated noise and on the weighting estimation;
calculating a negative logarithm of the projection measurement data;
applying a mean preservation to the projection measurement data after calculating the negative logarithm; and
reconstructing an image using the de-noised projection measurement data.
9. The method of claim 8 , further comprising estimating the noise based on a variance of each measurement using an x-ray count.
10. The method of claim 9 , further comprising estimating the variance based on an assumed Poisson distribution.
11. The method of claim 9 , further comprising correlating the noise estimation based on at least one of a view, a channel, and a row of CT imaging data in projection space.
12. The method of claim 8 , further comprising estimating a noise term after the image is reconstructed and in image space.
13. The method of claim 8 , further comprising correlating a noise estimate in a 3D image volume measured among one of a neighboring pixel or a neighboring patch of pixels.
14. A non-transitory computer readable storage medium having stored thereon a computer program comprising instructions, which, when executed by a computer, cause the computer to:
perform an air calibration step on computed tomography (CT) imaging data, wherein the CT imaging data comprises projection measurement data
estimate noise in the projection measurement data;
correlate the noise estimation with neighboring projection measurement data to generate a weighting estimation based on the correlation;
de-noise the projection measurement data based on the estimation and on the weighting;
calculate a negative logarithm of the projection measurement data;
apply a mean preservation to the projection measurement data after calculating the negative logarithm; and
reconstruct an image using the de-noised projection measurement data.
15. The non-transitory computer readable storage medium of claim 14 , wherein the computer is further caused to estimate the noise based on a variance of each measurement using an x-ray count, and based on an assumed Poisson distribution.
16. The non-transitory computer readable storage medium of claim 14 , wherein the computer is further programmed to estimate noise in image space.
17. The non-transitory computer readable storage medium of claim 14 , wherein the computer is further caused to correlate a noise estimate in a 3D image volume measured among one of a neighboring pixel or a neighboring patch of pixels.