X-ray CT apparatus and image reconstruction method

1. An X-ray CT apparatus comprising:

an X-ray source for irradiating an X-ray to an object from the surroundings;

an X-ray detector for detecting an X-ray transmitted through the object;

an image processing device for generating projection data from the detected information about the transmitted X-ray and reconstructing a tomographic image of the object based on the projection data; and

a display device for displaying the tomographic image,

wherein the image processing device comprises:

a motion direction obtaining unit for obtaining a motion direction of a site to be scanned;

a reconstruction data range calculation unit for calculating a reconstruction data range that is a range of projection data to be used for reconstruction based on the motion direction; and

an image reconstruction unit for reconstructing an image using the projection data of the calculated reconstruction data range.

2. The X-ray CT apparatus according to claim 1 ,

wherein the reconstruction data range calculation unit sets projection data in a projection range of at least 180 degrees or more including a projection direction approximately corresponding to a motion direction of the site to be scanned, as the reconstruction data range.

3. The X-ray CT apparatus according to claim 2 ,

wherein the reconstruction data range calculation unit sets projection data in a projection range in which a distance between the site to be scanned and the X-ray source is closer from among the projection data in a projection range of at least 180 degrees or more including a projection direction same as a motion direction of the site to be scanned, as the reconstruction data range.

4. The X-ray CT apparatus according to claim 1 , further comprising:

an input unit for inputting the motion direction,

wherein the motion direction obtaining unit obtains the motion direction input by the input unit.

5. The X-ray CT apparatus according to claim 4 ,

wherein an angle of a line showing the motion direction input to the input unit, and

the motion direction obtaining unit obtains the line angle as the motion direction.

6. The X-ray CT apparatus according to claim 5 ,

wherein a position of a motion center is further input to the input unit.

7. The X-ray CT apparatus according to claim 1 , further comprising:

a storage unit for storing a motion direction according to the site to be scanned and a posture of the object,

wherein the motion direction obtaining unit obtains the motion direction according to the site to be scanned and the posture of the object that are set as scanning conditions, from the storage unit.

8. The X-ray CT apparatus according to claim 1 , further comprising:

a motion detecting unit for detecting motion information of the site to be scanned,

wherein the motion direction obtaining unit obtains a motion direction of the site to be scanned from the motion information detected by the motion detecting unit.

9. The X-ray CT apparatus according to claim 8 ,

wherein the motion detecting unit calculates motion information of the site to be scanned based on each of opposite projection data.

10. The X-ray CT apparatus according to claim 8 ,

wherein the motion detecting unit calculates motion information of the site to be scanned based on opposite images reconstructed respectively using projection data in opposite ranges.

11. The X-ray CT apparatus according to claim 8 , further comprising:

a detection target area designating unit for designating a motion detection target area,

wherein the motion detecting unit detects the motion information in the motion detection target area.

12. The X-ray CT apparatus according to claim 1 , further comprising:

a motion amount calculation unit for calculating a motion amount of the site to be scanned,

wherein the reconstruction data range calculation unit calculates the reconstruction data range based on the motion amount calculated by the motion amount calculation unit and the motion direction.

13. The X-ray CT apparatus according to claim 1 ,

wherein the reconstruction data range calculation unit calculates the reconstruction data range for each position of images to be generated.

14. The X-ray CT apparatus according to claim 1 ,

wherein an X-ray control unit is further included for controlling so that the X-ray source irradiates an X-ray at an X-ray irradiation angle equivalent to a reconstruction data range calculated by the reconstruction data range calculation unit.

15. The X-ray CT apparatus according to claim 1 , further comprising:

a motion amount calculation unit for calculating a motion amount of the site to be scanned, and

an X-ray control unit for controlling so that the X-ray source irradiates an X-ray at an X-ray irradiation angle equivalent to the reconstruction data range calculated by the reconstruction data range calculation unit based on the motion amount calculated by the motion amount calculation unit and the motion direction.

16. An image reconstruction method including:

a projection data generation step of generating projection data in which the inside of an object was scanned;

a motion direction obtaining step of obtaining a motion direction of a site to be scanned;

a reconstruction data range calculation step of calculating a reconstruction data range that is a range of projection data to be used for reconstruction based on the motion direction; and

an image reconstruction step of reconstructing an image using projection data in the calculated reconstruction data range.