X-ray CT system and medical processing apparatus

1. An X-ray CT system comprising processing circuitry configured to:

execute first scanning of acquiring a first subject data set corresponding to first X-ray energy by irradiating a first region of a subject with X-rays;

execute, after the first scanning, second scanning of acquiring a second subject data set corresponding to second X-ray energy and a third subject data set corresponding to third X-ray energy different from the second X-ray energy by irradiating a second region included in the first region with X-rays; and

perform material decomposition among a plurality of reference materials based on: a fourth subject data set obtained based on the first subject data set and one of the second subject data set and the third subject data set; and the other of the second subject data set and the third subject data set.

2. The X-ray CT system according to claim 1 , wherein the processing circuitry

acquires a first projection data set as the first subject data set through execution of the first scanning by irradiating the first region extending in a body axis direction of the subject with X-rays,

acquires a second projection data set as the second subject data set and acquires a third projection data set as the third subject data set through execution of, after the first scanning, the second scanning by irradiating a second region narrower than the first region extending in the body axis direction with X-rays,

generates, based on the first projection data set, at least one of a fourth projection data set corresponding to the second X-ray energy and a fifth projection data set corresponding to the third X-ray energy, and

performs the material decomposition based on: the fourth projection data set and the second projection data set; the fourth subject data set obtained based on one of the fifth projection data set and the third projection data set; and the other of the second projection data set and the third projection data set.

3. The X-ray CT system according to claim 1 , wherein the first X-ray energy is different from the second X-ray energy and the third X-ray energy.

4. The X-ray CT system according to claim 2 , wherein

the second X-ray energy is smaller than the third X-ray energy, and

the processing circuitry

generates the fourth projection data set corresponding to the second X-ray energy based on the first projection data set,

generates a sixth projection data set corresponding to the second X-ray energy based on the second projection data set and the fourth projection data set, and

performs the material decomposition based on the third projection data set and the sixth projection data set.

5. The X-ray CT system according to claim 2 , wherein the processing circuitry

generates, based on the first projection data set, the fourth projection data set corresponding to the second X-ray energy and the fifth projection data set corresponding to the third X-ray energy,

generates, based on the second projection data set and the fourth projection data set, a sixth projection data set corresponding to the second X-ray energy,

generates, based on the third projection data set and the fifth projection data set, a seventh projection data set corresponding to the third X-ray energy, and

performs the material decomposition based on the sixth projection data set and the seventh projection data set.

6. The X-ray CT system according to claim 4 , wherein the processing circuitry generates the fourth projection data set by generating three-dimensional first image data based on the first projection data set, segmenting the first image data in accordance with an X-ray absorption coefficient, and sequentially projecting the segmented first image data in accordance with the second X-ray energy.

7. The X-ray CT system according to claim 5 , wherein the processing circuitry generates the fourth projection data set by generating three-dimensional first image data based on the first projection data set, segmenting the first image data in accordance with an X-ray absorption coefficient, and sequentially projecting the segmented first image data in accordance with the second X-ray energy, and generates the fifth projection data set by sequentially projecting the segmented first image data in accordance with the third X-ray energy.

8. The X-ray CT system according to claim 4 , wherein the processing circuitry generates the sixth projection data set by inputting the fourth projection data set and the second projection data set to a learned model functionalized to receive inputting of two projection data sets acquired from an identical target and output a high-quality projection data set.

9. The X-ray CT system according to claim 5 , wherein the processing circuitry generates the sixth projection data set by inputting the fourth projection data set and the second projection data set to a learned model functionalized to receive inputting of two projection data sets acquired from an identical target and output a high-quality projection data set, and generates the seventh projection data set by inputting the fifth projection data set and the third projection data set to the learned model.

10. The X-ray CT system according to claim 1 , wherein the processing circuitry executes the second scanning by changing X-ray energy between the second X-ray energy and the third X-ray energy for each of one or a plurality of views.

11. The X-ray CT system according to claim 1 , wherein the processing circuitry executes the second scanning by emitting X-rays of the second X-ray energy through a first X-ray tube and emitting X-rays of the third X-ray energy through a second X-ray tube.

12. The X-ray CT system according to claim 1 , wherein the processing circuitry executes the second scanning by using a layered X-ray detector including a first layer that detects X-rays of the second X-ray energy and a second layer that detects X-rays of the third X-ray energy.

13. The X-ray CT system according to claim 1 , wherein the processing circuitry executes the second scanning by using a first X-ray filter that attenuates an X-ray transmitting through the first X-ray filter to the second X-ray energy and a second X-ray filter that attenuates an X-ray transmitting through the second X-ray filter to the third X-ray energy.

14. The X-ray CT system according to claim 1 , wherein the processing circuitry executes the second scanning by attenuating part of X-rays incident on the subject by using an X-ray filter that attenuates an X-ray transmitting through the X-ray filter from the second X-ray energy to the third X-ray energy.

15. A medical processing apparatus comprising processing circuitry configured to perform material decomposition among a plurality of reference materials based on: a fourth subject data set obtained based on a first subject data set corresponding to first X-ray energy and acquired by irradiating a first region of a subject with X-rays in first scanning and one of a second subject data set corresponding to second X-ray energy and a third subject data set corresponding to third X-ray energy different from the second X-ray energy, the second subject data set and the third subject data set being acquired by irradiating a second region included in the first region with X-rays in second scanning executed after the first scanning; and the other of the second subject data set and the third subject data set.