Patent Number: 047180765
Section: summary

BACKGROUND OF THE INVENTION The present invention relates to an X-ray imaging apparatus suitable for use in medical diagnosis. When medical radiography is carried out using the conventional X-ray imaging apparatus, the resolution and contrast of the reproduced image are likely to be degraded because of scattered X-rays generated from the object to be imaged. A demand for a high-speed X-ray imaging apparatus which enables a short exposure time has arisen these days. The amount of irradiated X-rays must be increased to achieve a high speed operation. However, there is a limitation on increasing the amount of X-rays, because an X-ray generator has a limited load. Accordingly, Japanese Patent Disclosure (KOKAI) No. 53/7190, for example, discloses an X-ray imaging apparatus including an X-ray generator of the electronic beam scanning type which serves to move the X-ray irradiating position of an X-ray generating target, which has a slit plate positioned between the X-ray generator and the object to be imaged, which has substantially a single slit through which X-rays are allowed to pass, and which has an X-ray image detector positioned behind the slit plate to reproduce the X-ray image which is formed after X-rays pass through the slits and the object. In the case of this type of X-ray imaging apparatus, however, it is difficult to obtain a sufficient amount of X-rays and thus high S/N (signal to noise ratio) because the X-ray generator is of the stationary target type. It is also difficult to achieve high resolution because the X-ray detecting characteristic is discontinuous. U.S. Pat. No. 4,179,100 discloses an apparatus wherein an X-ray image is reproduced in such a way that an X-ray beam which has passed through a single slit of a slit plate is further passed through an object to be imaged, and then is introduced into an X-ray detector such as a fluorescent screen or an X-ray image intensifier to be converted to an optical image. However, the object, slit plate, X-ray generator and the like are mechanically moved. In this case, it is necessary to move them over a wide range of length in order to image the whole area of the object. Thus, it is difficult to achieve a high speed operation or a short exposure time. In addition, blur is still left in the reproduced X-ray image because of scattered X-rays generated in the object and because of veiling glares generated in the image intensifier by the scattered rays and the discharging of undesired floating electrons, thereby making it difficult to achieve a satisfactory resolution and contrast. SUMMARY OF THE INVENTION The present invention is therefore intended to eliminate the above-mentioned drawbacks. The object of the present invention is to provide an X-ray imaging apparatus wherein a high speed operation is made possible, wherein scattered X-rays in an object can be controlled and, whereby images having high resolution, high S/N and contrast can be produced. According to the invention, there is provided an X-ray imaging apparatus comprising: an X-ray generator including an electron gun for emitting an electron beam, a rotating cylindrical target for receiving an electron beam emitted from the electron gun and irradiating X-rays, and a deflection means for moving an electron beam of said electron gun on the target along the axis thereof; a slit plate separated by a certain distance from the X-ray generator and having an elongated slit extending in a direction perpendicular to the direction in which an X-ray focal point moves following the movement of said electron beam, to allow X-rays to pass therethrough; an X-ray image detector means arranged opposite to the slit plate with an object to be imaged interposed between them and serving to convert X-ray images created by the X-ray beams which have passed through the slit of said slit plate and the object, to electrical signal images; a signal processing means for picking up those signals from the electrical signal images obtained through the X-ray image detector means which correspond to X-ray images entering into areas on said X-ray image detector means when the slit is projected from positions of the X-ray focal point on said target; and an X-ray image reproducing means for displaying image signals processed by said signal processing means and obtained corresponding to the X-ray images. According to the invention, there is further provided an X-ray imaging apparatus comprising: an X-ray generator including an electron gun for emitting electron beam, an anode target for receiving the electron beam emitted from the electron gun to irradiate X-rays, and a deflection means for moving the electron beam of said electron gun on the target along the axis thereof; a slit plate separated by a certain distance from the X-ray generator and having a plurality of elongated slits each extending in a direction perpendicular to the direction in which an X-ray focal point moves following the movement of said electron beam, to allow X-rays to pass therethrough; an X-ray detector means arranged opposite to the slit plate with an object to be imaged interposed between them and serving to convert X-ray images created by the X-ray beams which have passed through the slits of said slit plate and the object, to electrical signal images; a signal processing means for picking up those signals from the electrical signal images obtained through the X-ray image detector means which correspond to X-ray images entering into areas on said X-ray image detector means when the slits are projected from positions of the X-ray focal point on said target; and an X-ray image reproducing means for displaying image signals processed by said signal processing means and obtained corresponding to the X-ray images. There is still further provided an X-ray imaging apparatus comprising: an X-ray generator including an electron gun for emitting an electron beam and a stationary anode target for receiving the electron beam emitted from the electron gun to irradiate X-rays; a slit plate separated by a certain distance from the X-ray generator and having a plurality of elongated slits, the slit plate being moved in a direction perpendicular to the direction in which the plurality of slits extend; a X-ray detector means arranged opposite to the slit plate with a subject to be imaged interposed between them and serving to convert X-ray images created by the X-ray beams which have passed through the slits of said slit plate and the subject, to electrical signal images; a signal processing means for picking up those signals from the electrical signal images obtained through the X-ray image detector means which correspond to X-ray images entering into areas on said X-ray image detector means when the slits are projected from the position of the X-ray focal point on said target; and an X-ray image reproducing means for displaying image signals processed by said signal process means and obtained corresponding to the X-ray images.