System and method of computed tomography signal restoration via noise reduction

Patent metadata

Field	Value
Publication number	US-9406107-B2
Application number	US-201314132321-A
Country	US
Kind code	B2
Filing date	Dec 18, 2013
Priority date	Dec 18, 2013
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

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.

First claim

What is claimed is:

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.

Assignees

• Gen Electric

Inventors

• Fan Jiahua
• Yue Meghan L
• Hsieh Jiang
• Melnyk Roman
• Nukui Masatake
• Yazaki Yujiro

Classifications

• A61B6/582

  Calibration · CPC title

• G06T2207/20182

  Noise reduction or smoothing in the temporal domain; Spatio-temporal filtering · CPC title

• A61B6/5205

  involving processing of raw data to produce diagnostic data · CPC title

• G01N2223/419

  computed tomograph · CPC title

• G06T2207/10081

  Computed x-ray tomography [CT] · CPC title