Reconstructing dual-energy CT images

Patent metadata

Field	Value
Publication number	US-10529095-B2
Application number	US-201815871131-A
Country	US
Kind code	B2
Filing date	Jan 15, 2018
Priority date	Jan 16, 2017
Publication date	Jan 7, 2020
Grant date	Jan 7, 2020

Abstract

Methods and devices for reconstructing dual-energy CT images are provided. In one aspect, CT scan is performed with a high energy and a low energy periodically and alternatively changed on a scanning target, reconstruction data for a high-energy image of a current reconstruction position is obtained based on whether a circle of high-energy scan closest to the current reconstruction position of the scanning target is a full circle of scan, the high-energy image of the current reconstruction position is reconstructed according to the reconstruction data of the high-energy image; reconstruction data for a low-energy image of the current reconstruction position is obtained based on whether a circle of high-energy scan closest to the current reconstruction position of the scanning target is the full circle of scan, the low-energy image of the current reconstruction position is reconstructed according to the reconstruction data of the low-energy image.

First claim

What is claimed is:

1. A method of reconstructing dual-energy CT images, comprising:
performing a CT scan with a high energy and a low energy periodically and alternatively changed on a scanning target, wherein a scanning angle range for each full circle of high-energy scan and a scanning angle range for each full circle of low-energy scan are respectively from 0 to θ max ;
determining whether a circle of high-energy scan closest to a current reconstruction position of the scanning target is a full circle of scan;
when the circle of high-energy scan closest to a current reconstruction position of the scanned target is the full circle of scan,
obtaining a first set of projection data corresponding to the full circle of high-energy scan as reconstruction data for a high-energy image corresponding to the current reconstruction position;

when the circle of high-energy scan closest to the current reconstruction position of the scanned target is not the full circle of scan,
obtaining a second set of projection data corresponding to a non-full circle of high-energy scan, wherein a scanning angle range corresponding to the non-full circle of high-energy scan is from 0 to θ high-end , 0<θ high-end <θ max ,
truncating a third set of projection data corresponding to a scanning angle range from θ high-end to θ max from projection data corresponding to a full circle of high-energy scan before the non-full circle of scan;
merging the second set of projection data and the third set of projection data as the reconstruction data for the high-energy image of the current reconstruction position;

reconstructing the high-energy image of the current reconstruction position according to the reconstruction data of the high-energy image;
determining whether a circle of low-energy scan closest to a current reconstruction position of the scanning target is a full circle of scan;
when the circle of low-energy scan closest to a current reconstruction position of the scanned target is the full circle of scan,
obtaining a fourth set of projection data corresponding to the full circle of low-energy scan as reconstruction data for a low-energy image corresponding to the current reconstruction position;

when the circle of low-energy scan closest to the current reconstruction position of the scanned target is not the full circle of scan,
obtaining a fifth set of projection data corresponding to a non-full circle of low-energy scan, wherein a scanning angle range corresponding to the non-full circle of low-energy scan is from 0 to θ low-end , 0<θ low-end <θ max ,
truncating a sixth set of projection data corresponding to a scanning angle range from θ low-end to θ max from projection data corresponding to a full circle of low-energy scan before the non-full circle of scan;
merging the fifth set of projection data and the sixth set of projection data as the reconstruction data for the low-energy image of the current reconstruction position;

reconstructing the low-energy image of the current reconstruction position according to the reconstruction data of the low-energy image.

2. The method of claim 1 , wherein
the full circle of high-energy scan corresponding to the second set of projection data and the non-full circle of high-energy scan are spaced by a full circle of low-energy scan when the circle of high-energy scan closest to the current reconstruction position is the non-full circle of high-energy scan; and
the full circle of low-energy scan corresponding to the fifth set of projection data and the non-full circle of the low-energy scan are spaced by a full circle of the high-energy scan when the circle of the low-energy scan closest to the current reconstruction position is the non-full circle of low-energy scan.

3. The method of claim 1 , further comprising:
determining a circle of high-energy scan passing through the current reconstruction position to be the circle of high-energy scan closest to the current reconstruction position when the high-energy scan is performed on the current reconstruction position.

4. The method of claim 3 , further comprising:
when the low-energy scan is not performed on the current reconstruction position,
calculating a first distance between the current reconstruction position and a finishing position of a previous circle of low-energy scan adjacent to the circle of high-energy scan passing through the reconstruction position and a second distance between the current reconstruction position and a starting position of a next circle of the low-energy scan adjacent to the circle of high-energy scan passing through the current reconstruction position, respectively; and
determining the circle of low-energy scan corresponding to a smaller one of the first distance and the second distance to be the circle of the low-energy scan closest to the current reconstruction position.

5. The method of claim 1 , further comprising:
determining a circle of low-energy scan passing through the current reconstruction position to be the circle of low-energy scan closest to the current reconstruction position when the low-energy scan is performed on the current reconstruction position.

6. The method of claim 5 , further comprising:
when the high-energy scan is not performed on the current reconstruction position,
calculating a third distance between the current reconstruction position and a finishing position of a previous circle of high-energy scan adjacent to the circle of low-energy scan passing through the reconstruction position and a fourth distance between the current reconstruction position and a starting position of a next circle of high-energy scan adjacent to the circle of low-energy scan passing through the current reconstruction position, respectively; and
determining the circle of high-energy scan corresponding to a smaller one of the third distance and the fourth distance to be the circle of high-energy scan closest to the current reconstruction position.

7. The method of claim 1 , wherein the CT scan is spiral scan, an overlapping part of a circle of high-energy scan and a circle of the low-energy scan adjacent with each other is an energy switching area, and projection data corresponding to the energy switching area is invalid.

8. A device for reconstructing a dual-energy CT image, comprising:
a processor, and
a non-transitory machine-readable storage medium storing machine executable instructions which are executable by the processor to:
perform CT scan with a high energy and a low energy periodically and alternatively changed on a scanning target, wherein a scanning angle range for each full circle of high-energy scan and a scanning angle range for each full circle of low-energy scan are respectively from 0 to θ max ;
determine whether a circle of high-energy scan closest to a current reconstruction position of the scanning target is a full circle of scan;
when the circle of high-energy scan closest to a current reconstruction position of the scanned target is the full circle of scan,
obtain a first set of projection data corresponding to the full circle of high-energy scan as reconstruction data for a high-energy image corresponding to the current reconstruction position;

when the circle of high-energy scan closest to the current reconstruction position of the scanned target is not the full circle of scan,
obtain a second set of projection data corresponding to a non-full circle of high-energy scan, wherein a scanning angle range corresponding to the non-full circle of high-energy scan is from 0 to θ high-end , 0<θ high-end <θ max ,
truncate a third set of projection data corresponding to a scanning angle range from θ high-end to θ max from projection data corresponding to a full circle of high-energy scan b

Assignees

• Shenyang Neusoft Medical Sys

Inventors

• Li Shuangxue
• Lou Shanshan
• Tong Lixia

Classifications

• G06T2211/436

  Limited angle · CPC title

• G06T2211/408

  Dual energy · CPC title

• G06T12/20 Primary

  Inverse problem, i.e. transformations from projection space into object space · CPC title

• G06T12/10 Primary

  Image preprocessing, e.g. calibration, positioning of sources or scatter correction · CPC title

• A61B6/52 Primary

  Devices using data or image processing specially adapted for radiation diagnosis · CPC title