Radiographic apparatus and control method therefor

1. A radiographic apparatus for applying radiation from a radiation source and taking a radiation image, comprising:

a radiation sensor for acquiring a spatial intensity distribution of radiation as two-dimensional image data;

a fluctuation detecting unit for detecting fluctuations of the pressure applied to said radiation sensor; and

an acquisition unit for acquiring, when a coefficient of pressure fluctuation based on fluctuation information which is output from said fluctuation detecting unit, is smaller than a threshold value, at least one of the radiation image and an offset image based on the two-dimensional image data acquired from said radiation sensor.

2. A radiographic apparatus according to claim 1 , wherein the pressure fluctuation information is calculated based on the offset image.

3. A radiographic apparatus according to claim 1 , further comprising:

an offset correction unit for making offset correction of the radiation image using the offset image.

4. A radiographic apparatus according to claim 1 , wherein the coefficient of pressure fluctuation is calculated based on an acquiring period for the radiation image and the offset image.

5. A radiographic apparatus according to claim 1 , wherein

the coefficient of pressure fluctuation is calculated with regard to a plurality of sub-regions into which said radiation sensor is divided, and

the acquisition unit acquires the radiation image and the offset image from the two-dimensional image data when the coefficient of pressure fluctuation is smaller than the threshold value in a central area of the plurality of sub-regions.

6. A radiographic apparatus according to claim 1 , wherein the coefficient of pressure fluctuation is calculated based on any one of output of a pressure sensor for measuring the pressure applied to said radiation sensor, the offset image acquired based on the two-dimensional image data, and output of an acceleration sensor placed in said radiation sensor.

7. A radiographic apparatus according to claim 6 , wherein the pressure sensor is placed on the back of a surface of said radiation sensor on which the radiation is incident.

8. A radiographic apparatus according to claim 6 , wherein, when the pressure sensor is placed between a grid and a surface of said radiation sensor on which the radiation is incident, gain image correction for canceling a transmission image of the radiation of the pressure sensor is made.

9. A radiographic apparatus according to claim 3 , wherein the threshold value is determined based on conditions of generating radiation by a radiation source.

10. A control method of controlling a radiographic apparatus for applying radiation from a radiation source and taking a radiation image, comprising:

detecting fluctuation information on a pressure applied to a radiation sensor;

acquiring spatial intensity distribution of radiation as two-dimensional image data; and

acquiring, when a coefficient of pressure fluctuation based on fluctuation information which is output from the fluctuation detecting unit, is smaller than a threshold value, at least one of the radiation image and an offset image based on the two-dimensional image data acquired from the radiation sensor.

11. A control method for a radiographic apparatus, the radiographic apparatus comprising a radiation generating unit for generating radiation and applying the radiation to a subject, and an image detecting unit for detecting as a radiation image radiation which passes through the subject under a state in which radiation is applied to the subject from the radiation generating unit and detecting an offset image under a state in which radiation is not applied to the subject from the radiation generating unit, the method comprising:

detecting pressure information fluctuations applied to the image detecting unit;

acquiring the radiation image and the offset image from the image detecting unit when a coefficient of pressure fluctuation based on the pressure information fluctuations detected in the detecting of the pressure information fluctuations is smaller than a threshold value; and

making offset correction of the radiation image acquired in the acquiring, using the offset image acquired in the acquiring.

12. A non-transitory, computer-readable recording medium having stored therein, in executable form, a program for causing a computer to carry out the control method according to claim 10 .

13. A radiographic apparatus according to claim 1 , further comprising:

a control unit for controlling the radiation from the radiation source based on the pressure fluctuation information of the pressure applied to said radiation sensor.

14. A radiographic apparatus according to claim 13 , wherein said control unit allows the radiation when an amount of fluctuations acquired from the fluctuation information is equal to or smaller than a predetermined value.

15. A radiographic apparatus according to claim 13 , wherein said control unit controls the radiation of the radiation source based on the fluctuation information as output of said fluctuation detecting unit.