X-ray apparatus

Claim 1

An X-ray apparatus used in stereoradiography of an object, comprising: an X-ray tub having a pair of X-ray focal points placed a predetermined distance apart from each other in a first direction, the pair of X-ray focal points emitting a pair of irradiating X-ray beams toward the object along a second direction approximately perpendicular to the first direction; an X-ray detector having a circular input window and a detection surface for receiving X-ray beams transmitted from the X-ray tube and irradiated through the object; and an X-ray beam limiting device, arranged between said X-ray tube and said object, for limiting irradiation fields of the X-ray beams, including; a first set of blades made of an X-ray shielding material including two first blades, each blade having a front with a notch therethrough for allowing X-ray beams from said X-ray tube to pass therethrough, and each blade having a back opposed to the front of the blade, the two first blades being arranged back to back along a third direction approximately perpendicular to the first and second directions in a space between the pair of X-ray beams; a first driving unit for supporting the two first blades pivotally around an axis parallel to the third direction and for pivoting said first blades in response to a control signal; a second set of blades made of X-ray shielding plates which are substantially impenetrable to X-rays and include two second blades, each second blade having a notch therethrough for allowing said irradiating X-ray beams to pass therethrough, the two second blades arranged between said first set of blades and said object and arranged such that the notches of the second blades face each other; a second driving unit for supporting the two second blades slidably in a direction parallel to the third direction and for moving said second blades in response to said control signal; a third set of blades made of X-ray shielding plates and including a plurality of third blades arranged to form an adjustable rectangular aperture approximately perpendicular to said irradiating X-ray beams, said third set of blades located between said second set of blades and said object; a third driving unit for supporting said third set of blades and for moving the plurality of third blades to adjust the rectangular aperture in response to said control signal; means for controlling the first, second, and third driving units by supplying the control signal in accordance with at least one of a distance between said X-ray tube and said X-ray detector, and a size of the input window of the X-ray detector.