Patent Number: 
Section: claims

1. A radiographic image capturing apparatus comprising:a radiation source configured to apply radiation to an object of a subject to be examined;a radiation detector configured to detect the radiation that has passed through the object and configured to convert the detected radiation into a radiographic image;a collimator configured to delimit an irradiated field of the radiation with respect to the radiation detector, the collimator being disposed between the radiation source and the object;a biopsy region positional information calculating unit configured to calculate a three-dimensional position of a biopsy region in the object based on two radiographic images, which are acquired by the radiation detector in a stereographic image capturing process, in which the radiation source disposed at least at two angles applies the radiation to the object;an irradiated field calculating unit configured to calculate a new irradiated field covering the biopsy region based on the calculated three-dimensional position of the biopsy region and the two angles;a collimator control unit configured to control the collimator to change the irradiated field of the radiation in a next stereographic image capturing process to the new irradiated field; andan irradiated field calculation control unit configured to selectively enable the irradiated field calculating unit to calculate the new irradiated field or disable the irradiated field calculating unit from calculating the new irradiated field. 2. A radiographic image capturing apparatus according to claim 1, wherein the application of the radiation to the object from the radiation source at the two angles, the calculation of the three-dimensional position of the biopsy region by the biopsy region positional information calculating unit, the calculation of the new irradiated field by the irradiated field calculating unit, and the changing of the irradiated field of the radiation to the new irradiated field by the collimator control unit are successively carried out repeatedly. 3. A radiographic image capturing apparatus according to claim 1, further comprising a light source for spotlighting the radiation detector to indicate the irradiated field thereon, before the radiation source applies the radiation to the object. 4. A radiographic image capturing apparatus according to claim 1, wherein on condition that the irradiated field calculation control unit determines that the biopsy region will possibly be included in the two radiation images to be acquired even after converting the irradiated field to the new irradiated field in the next stereographic image capturing process, then calculation of the new irradiated field by the irradiated field calculating unit is enabled, andon condition that the irradiated field calculation control unit determines that the biopsy region will not possibly be included in the two radiation images to be acquired after converting the irradiated field to the new irradiated field in the next stereographic image capturing process, calculation of the new irradiated field by the irradiated field calculating unit is disabled. 5. A radiographic image capturing apparatus according to claim 4, wherein in the case that the calculation of the new irradiated field is enabled, the irradiated field calculating unit is configured to calculate the new irradiated field using the three-dimensional position of the biopsy region based on the radiographic image in a last stereographic image capturing process and the two angles acquired by the radiation detector in the last stereographic image capturing process. 6. A radiographic image capturing apparatus according to claim 5, wherein the irradiated field calculating unit is configured to determine a field restricted from the irradiated field, as the new irradiated field in the next stereographic image capturing process. 7. A radiographic image capturing apparatus according to claim 4, wherein in the case that the calculation of the new irradiated field is disabled, a stereographic image capturing process is carried out under the same conditions as the last stereographic image capturing process. 8. A radiographic image capturing method comprising the steps of:performing a stereographic image capturing process by applying radiation from a radiation source disposed at least at two angles to an object of a subject to be examined, while an irradiated field of the radiation with respect to a radiation detector is being delimited by a collimator;detecting, with the radiation detector, the radiation applied from the radiation source disposed at the two angles to acquire two radiographic images;calculating, with a biopsy region positional information calculating unit, a three-dimensional position of a biopsy region in the object based on the two radiographic images;calculating, with an irradiated field calculating unit, a new irradiated field covering the biopsy region based on the calculated three-dimensional position of the biopsy region and the two angles;controlling the collimator with a collimator control unit to change the irradiated field of the radiation in a next stereographic image capturing process to the new irradiated field; andselectively enabling the irradiated field calculating unit to calculate the new irradiated field or disabling the irradiated field calculating unit from calculating the new irradiated field.