Patent Number: 
Section: claims

1. An X-ray shield device for use with an X-ray fluoroscopic apparatus for fluoroscopically visualizing a certain site of a subject, comprising an X-ray generator containing an X-ray source, an X-ray detector associated with the X-ray generator and including a projection plane disposed opposed to the X-ray source, and a support member disposed between the X-ray source and the projection plane for supporting the subject, the X-ray shield device being adapted to prevent a specified site of the subject from exposing to the X-ray from the X-ray source, said X-ray shield device comprising:at least one X-ray shielding plate positioned between the X-ray source and the support member;output means for outputting position data of said support member;a shielding plate driving mechanism including a supporting portion for supporting said at least one X-ray shielding plate, said shielding plate driving mechanism being operable to move the shielding plate supported by the supporting portion in a direction transverse to a path of X-ray irradiation;shielding position determining means for determining a shielding position where the irradiation from the X-ray should be shielded, wherein the shielding position determining means comprises:(a) a position of x-ray source measuring device for measuring the position of the x-ray source S relative to a common reference point;(b) a position of shielding plate driving mechanism measuring device for measuring the position of the shielding plate driving mechanism relative to said common reference point;(c) a position of non-irradiation site measuring device for measuring the position of said specified site relative to said common reference point based on the position data from the output means and a previously measured distance between the support member and the specified site; and(d) a computing unit for computing said shielding position based on data from said X-ray source position measuring device, data from said shielding plate driving mechanism position measuring device and data from said non-irradiation position measuring device; anda control unit for controlling operation of said shielding plate driving mechanism to cause movement of said shielding plate to said shielding position in a manner so as to shield said specified site of the subject from the X-ray from the X-ray source of the X-ray generator upon movement of the X-ray generator and the X-ray detector relative to the support member. 2. An X-ray shield device as defined in claim 1, wherein there are a plurality of said X-ray shielding plates, and wherein said supporting portion of the shielding plate driving mechanism is operable to support a selected one of said X-ray shielding plates of different sizes for exchange. 3. An X-ray shield device as defined in claim 2, wherein said shielding position is a position where said X-ray shielding plate is to be centered and at which a line extending centrally through the X-ray source and the specified site of the subject to be shielded from the X-ray irradiation from the X-ray source, intersects a plane in which said shielding plate is moved. 4. An X-ray shield device as defined in claim 3, further comprising a shielding plate size determining means for determining a size of said X-ray shielding plate to be placed at said shielding position that is suitable for said specified site of the subject to be shielded from the X-ray irradiation from the X-ray source. 5. An X-ray shield device as defined in claim 2, further comprising a shielding plate size determining means for determining a size of said X-ray shielding plate to be placed at said shielding position that is suitable for said specified site of the subject to be shielded from the X-ray irradiation from the X-ray source. 6. An X-ray shield device as defined in claim 1, further comprising shielding plate size determining means for determining a size of said X-ray shielding plate to be placed at said shielding position that is suitable for said specified site of the subject to be shielded from the X-ray irradiation from the X-ray source. 7. An X-ray shield device as defined in claim 6, wherein said shielding plate size determining means comprises:said shielding position determining means, a size of non-irradiation site storing device for storing data relating to the size of a non-irradiation site of the subject projected onto a plane perpendicular to the center line which passes through the X-ray source and the center of the non-irradiation site, and a computing unit for computing the size of the X-ray shielding plate suitable for the non-irradiation site of the subject based on data provided from said shielding position determining means and data provided from said non-irradiation site's size storing device. 8. An X-ray shield device as defined in claim 7, wherein said shielding plate driving mechanism is adapted to move the X-ray shielding plate along said path of X-ray irradiation. 9. An X-ray shield device as defined in claim 6, further comprising an X-ray shielding plate exchanging means for exchanging said X-ray shielding plate supported by said supporting portion of the X-ray shielding plate driving mechanism for another X-ray shielding plate of different size. 10. An X-ray shield device as defined in claim 6, wherein said shielding plate exchanging means comprises a shielding plate rack for releasably holding more than one X-ray shielding plates of different sizes;said supporting portion of the X-ray shielding plate driving mechanism is configured to releasably support said X-ray shielding plate;and said X-ray shielding plate driving mechanism is constructed to move the supporting portion thereof in such a manner that the supporting portion is caused to pass the X-ray shielding plate supported thereby onto said shielding plate rack which can hold that X-ray shielding plate and to receive thereon selected one of X-ray shielding plates held by the shielding plate rack. 11. An X-ray shield plate as defined in claim 10, wherein said control unit is operable to control said X-ray shielding plate exchanging means in such a manner that said supporting portion of the X-ray shielding plate driving mechanism is caused to pass the X-ray shielding plate supported thereby onto said shielding plate rack which can hold the X-ray shielding plate and to receive thereon at least one X-ray shielding plate held by the shielding plate rack whose size is determined by said shielding plate size determining means. 12. An X-ray shield device as defined in claim 1, further comprising a command input unit operatively connected to said control unit. 13. An X-ray shield device as defined in claim 1, wherein said X-ray shield device comprising at least two X-ray shielding plates positioned between the X-ray source and the support member in order to prevent a plurality of specified sites of the subject from exposing to the X-ray from the X-ray source, and at least two shielding plate driving mechanism each operable to move the respective X-ray shielding plate, each of said shielding plate driving mechanisms being adapted to move the respective X-ray shielding plate in a direction transverse to a respective path of X-ray irradiation at a different position on said X-ray irradiation path.