X-ray diagnostic apparatus, x-ray condition determination method, and non-transitory computer-readable medium

1 . An X-ray diagnostic apparatus, comprising:

processing circuitry configured to:

set a plurality of regions of interest (ROIs) in a first X-ray image;

set a priority to each of the ROIs;

calculate a statistical value relating to each of the ROIs based on a plurality of values of pixels included in each of the ROIs, thereby obtaining a plurality of statistical values;

acquire a threshold value relating to each of the statistical values;

acquire a maximum value and a minimum value relating to the threshold value of each of the statistical values; and

determine a set of X-ray conditions relating to capturing of a second X-ray image subsequent to the first X-ray image in such a manner that the statistical value of a ROI with a highest priority among the ROIs falls in a range between the threshold value and the maximum value, and the statistical value of at least one of the ROIs excluding the ROI with the highest priority falls in a range between the threshold value and the minimum value.

2 . The X-ray diagnostic apparatus according to claim 1 , wherein the processing circuitry is further configured to set the plurality of ROIs based on a user's input.

3 . The X-ray diagnostic apparatus according to claim 1 , wherein the processing circuitry is further configured to set one of the ROIs over an entire region or a substantially entire region of the first X-ray image, and set at least one of the ROIs excluding said one of the ROIs at at least one image region including at least one target photographed in the first X-ray image.

4 . The X-ray diagnostic apparatus according to claim 1 , wherein the processing circuitry is further configured to calculate, for each of the ROIs, a set of X-ray conditions under which the statistical value satisfies the threshold value, thereby obtaining a plurality of sets of X-ray conditions, and determine, as the set of X-ray conditions relating to capturing of the second X-ray image, a set of X-ray conditions under which irradiation is performed with a highest dose of X-rays, of the plurality of sets of X-ray conditions.

5 . The X-ray diagnostic apparatus according to claim 1 , wherein

the plurality of ROIs are two ROIs, and

the processing circuitry is further configured to determine the set of X-ray conditions relating to capturing of the second X-ray image in such a manner that the statistical value of each of the two ROIs satisfies the threshold value.

6 . The X-ray diagnostic apparatus according to claim 1 , wherein

the plurality of ROIs are three or more ROIs, and

the processing circuitry is further configured to determine the set of X-ray conditions relating to capturing of the second X-ray image in such a manner that the statistical value of each of at least two of the three or more ROIs satisfies the threshold value.

7 . The X-ray diagnostic apparatus according to claim 1 , wherein the processing circuitry is further configured to set, as the ROI with the highest priority, one of the ROIs including at least one target photographed in the first X-ray image.

8 . The X-ray diagnostic apparatus according to claim 1 , wherein the processing circuitry is further configured to calculate, as the statistical value, at least one of a mean value relating to the plurality of values of pixels included in each of the ROIs and an image quality index estimated based on the plurality of values of pixels.

9 . The X-ray diagnostic apparatus according to claim 8 , wherein the image quality index includes a contrast-to-noise ratio.

10 . The X-ray diagnostic apparatus according to claim 1 , wherein the processing circuitry is further configured to perform, if a halation region is present in the second X-ray image generated based on the determined set of X-ray conditions, a gain correction process on the second X-ray image to darken the halation region.

11 . The X-ray diagnostic apparatus according to claim 1 , further comprising:

an X-ray tube configured to generate X-rays; and

an X-ray attenuation filter arranged between the X-ray tube and a subject, including an opening configured to let X-rays for irradiating the subject pass through without reducing the X-rays, and including a dose-reducing portion arranged on a periphery of the opening and configured to reduce the X-rays,

wherein the processing circuitry is further configured to set, in the first X-ray image, an image region corresponding to the opening as one of the ROIs based on position information of the opening, and sets a peripheral region of said one of the ROIs as another ROI.

12 . The X-ray diagnostic apparatus according to claim 1 , wherein

at least one target photographed in the first X-ray image includes at least one of a medical device, a marker on the medical device, and an anatomical structure,

the medical device includes at least one of a catheter, a balloon catheter, a stent, a guide wire, a pacemaker, a transesophageal echo probe, and a prosthetic joint, and

the anatomical structure includes at least one of a bone, a tooth, a muscle, an organ, a blood vessel, and a nerve.

13 . An X-ray condition determination method performed by processing circuitry, the method comprising:

setting a plurality of regions of interest (ROIs) in a first X-ray image;

setting a priority to each of the ROIs;

calculating a statistical value relating to each of the ROIs based on a plurality of values of pixels included in each of the ROIs, thereby obtaining a plurality of statistical values;

acquiring a threshold value relating to each of the statistical values;

acquiring a maximum value and a minimum value relating to the threshold value of each of the statistical values; and

determining a set of X-ray conditions relating to capturing of a second X-ray image subsequent to the first X-ray image in such a manner that the statistical value of a ROI with a highest priority among the ROIs falls in a range between the threshold value and the maximum value, and the statistical value of at least one of the ROIs excluding the ROI with the highest priority falls in a range between the threshold value and the minimum value.

14 . A non-transitory computer-readable medium having recorded thereon a plurality of computer-executable instructions that cause the computer to execute the steps of:

setting a plurality of regions of interest (ROIs) in a first X-ray image;

setting a priority to each of the ROIs;

calculating a statistical value relating to each of the ROIs based on a plurality of values of pixels included in each of the ROIs, thereby obtaining a plurality of statistical values;

acquiring a threshold value relating to each of the statistical values;

acquiring a maximum value and a minimum value relating to the threshold value of each of the statistical values; and

determining a set of X-ray conditions relating to capturing of a second X-ray image subsequent to the first X-ray image in such a manner that the statistical value of a ROI with a highest priority among the ROIs falls in a range between the threshold value and the maximum value, and the statistical value of at least one of the ROIs excluding the ROI with the highest priority falls in a range between the threshold value and the minimum value.

15 . The X-ray condition determination method according to claim 13 , further comprising:

setting the plurality of ROIs based on a user's input.

16 . The X-ray condition determination method according to claim 13 , further comprising:

setting one of the ROIs over an entire region or a substantially entire region of the first X-ray image; and

setting at least one of the ROIs excluding said one of the ROIs at at least one image region including at least one target photographed in the first X-ray image.

17 . The X-ray condition determination method according to claim 13 , further comprising:

calculating, for each of the ROIs, a set of X-ray conditions under which the statistical value satisfies the threshold value, thereby obtaining a plurality of sets of X-ray conditions; and

determining, as the set of X-ray conditions relating to capturing of the second X-ray image, a set of X-ray conditions under which irradiation is performed with a highest dose of X-rays, of the plurality of sets of X-ray conditions.

18 . The X-ray condition determination method according to claim 13 , further comprising:

setting, as the ROI with the highest priority, one of the ROIs including at least one target photographed in the first X-ray image.