Abstract:
The present invention provides an X-ray radiography apparatus constructed so as to be capable of moving an X-ray generator to as low a position as possible. A X-ray radiography apparatus is of the X-ray radiography apparatus that includes a table which has a transverse direction and a longitudinal direction, and which includes a first X-ray detector and is capable of placing a subject thereon, an X-ray generator that applies X rays to the subject placed on the table, and an X-ray generator moving device that moves the X-ray generator in the longitudinal direction of the table and upward and downward directions thereof. The X-ray generator moving device includes a guide rail disposed in the longitudinal direction in the neighborhood of the table, a guide support post that guides the X-ray generator movably up and down, and a moving member which is formed in an L shape extending in a transverse direction and extending in a longitudinal direction and which is coupled to the guide rail and the guide support post and moved along the guide rail.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of Chinese Patent Application No. 200710092143.X filed Apr. 2, 2007, which is hereby incorporated by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    The subject matter disclosed herein relates to a radiation radiography apparatus (a radiation CR (Computed Radiography) apparatus), and specifically to an X-ray radiography apparatus capable of moving an X-ray tube. 
         [0003]    Upon diagnosis of a subject, an X-ray penetrated image of the subject is photographed or imaged depending on the state of a disease or injury of the subject while the subject remains standing. Alternatively, its X-ray penetrated image is photographed while the subject lies down on a table. Therefore, there is provided an X-ray radiography apparatus wherein in order to enable the radiography of the subject while the stand remains standing, a stand is provided with an X-ray detector and a table is provided with an X-ray detector. Even in the case of the X-ray detector of the stand and the X-ray detector of the table, an X-ray generator needs to apply an X-ray beam even to any region of the subject. 
         [0004]      FIG. 7  shows a conventional X-ray radiography apparatus  200 . The X-ray radiography apparatus  200  is equipped with a table  231  provided with an X-ray detector  234 - 1 , and a stand  232  provided with an X-ray detector  234 - 2 . An X-ray generator  210  including X-ray tube is placed on a movable guide support post  241 . The guide support post  241  is movable on rails disposed along the side surface of the table  231 . Thus, the X-ray generator  210  can apply an X-ray beam even to any region of a subject lying down on the table  231 . The stand  232  is disposed in the neighborhood of the table  231 . The X-ray generator  210  can apply an X-ray beam even to the X-ray detector  234 - 1  of the stand  232 . 
         [0005]    However, the X-ray generator  210  supported by the guide support post  241  can only photograph a region at a height of about 550 mm or more even when it is moved to the lowest position. When, for example, regions located below the knees of the subject are photographed or imaged in a state in which the subject is standing, it can photograph the same only when the subject lies down on the table  231 . Under such circumstances, there are cases in which it takes time to conduct a diagnosis and the subject suffers pain. 
         [0006]    Therefore, it is desirable is to provide an X-ray radiography apparatus constructed so as to be capable of moving an X-ray generator to as low a position as possible. 
       SUMMARY OF THE INVENTION 
       [0007]    A X-ray radiography apparatus of the present invention aims to provide an X-ray radiography apparatus capable of lowering an X-ray generator to a position as close as possible to a floor. 
         [0008]    In a first aspect, an X-ray radiography apparatus of the present invention comprises a table having a transverse direction and a longitudinal direction, which is provided with a first X-ray detector and capable of placing a subject thereon, an X-ray generator for applying X rays to the subject placed on the table, and an X-ray generator moving device for moving the X-ray generator in the longitudinal direction of the table and upward and downward directions thereof. And the X-ray generator moving device includes a guide rail disposed in the longitudinal direction in the neighborhood of the table, a guide support post that guides the X-ray generator movably up and down, and a moving member which is formed in an L shape extending in a transverse direction and extending in a longitudinal direction and which is coupled to the guide rail and the guide support post and moved along the guide rail. 
         [0009]    In the X-ray radiography apparatus according to the first aspect, the moving member is shaped in the L-shaped fashion. The guide support post for guiding the X-ray generator movably up and down is coupled to the moving member. Therefore, the X-ray generator can be lowered to near the floor without causing interference with the guide rail. It is thus possible to photograph the regions below the knees of the subject even in the standing state of the subject. 
         [0010]    In the X-ray radiography apparatus according to a second aspect, when it is desired to move the moving member to an edge portion of the guide rail, the guide support post is placed outside as viewed in a longitudinal direction thereof from the edge portion of the guide rail. 
         [0011]    In the X-ray radiography apparatus according to the second aspect, the guide support post is placed outside as viewed in the longitudinal direction from the edge portion of the guide rail. Therefore, there is a need to provide space in the longitudinal direction. However, even though broad space is not so required, the X-ray generator can be lowered to near the floor without interfering in the guide rail. 
         [0012]    The X-ray radiography apparatus according to a third aspect further includes a stand having a second X-ray detector and disposed adjacent to the subject. 
         [0013]    The X-ray radiography apparatus according to the third aspect is provided with the stand that enables radiography while the subject remains standing, together with the table on which the subject lies down. Thus, an operator is able to freely diagnose imaging regions according to diagnosed regions of the subject. 
         [0014]    In the X-ray radiography apparatus according to a fourth aspect, the X-ray generator moving device has a carrier included in the guide support post, which moves the X-ray generator in the transverse direction. 
         [0015]    In the X-ray radiography apparatus according to the fourth aspect, the X-ray generator can be moved not only in the longitudinal, upward and downward directions but also in the transverse direction. Therefore, the operator is able to freely move the X-ray generator to a region of the subject that needs its diagnosis. 
         [0016]    In the X-ray radiography apparatus according to a fifth aspect, the moving member has a sliding member that slides in contact with a floor. 
         [0017]    The moving member is of the L shape that extends in the transverse direction and extends in the longitudinal direction and is not placed on the guide rail. Thus, if the self weight of the moving member is not supported, then bending moment is applied to the guide rail, so that the guide rail becomes easy to fail. Therefore, if the moving member is provided with the sliding member, then its own weight can be supported by the sliding member. Thus, no bending moment is applied to the guide rail. Since the sliding member slides with the moving member, no problem occurs upon traveling of the moving member. Particularly when the moving member supports the weight of the guide support post as well as being coupled to the guide support post, the effect of the sliding member is large. 
         [0018]    In the X-ray radiography apparatus according to a sixth aspect, the guide support post has a sliding member that slides in contact with a floor. 
         [0019]    Since the guide support post is provided with the X-ray generator, its own weight is large and bending moment is applied even to the guide support post per se. If the self weight of the guide support post is not supported, then bending moment is applied to the guide rail, so that the guide rail becomes easy to fail or break down. Therefore, if the guide support post has the sliding member, no bending moment is applied to the guide rail because the self weight of the guide support post can be supported by the sliding member. Since the sliding member slides with the guide support post, no problem occurs upon the traveling of the guide support post. 
         [0020]    The X-ray radiography apparatus according to a seventh aspect is provided with a control device for controlling the traveling of the X-ray generator. When the moving member is placed in a first range as viewed in the longitudinal direction, the control device controls the X-ray generator in such a manner that the X-ray generator is moved up and down within a predetermined height range of the guide support post. 
         [0021]    In the X-ray radiography apparatus according to the seventh aspect, the moving member is moved up and down within the predetermined height range of the guide support post when the moving member is placed in the first range as viewed in the longitudinal direction. If the first range extends from end to end as viewed in the longitudinal direction of the table, then the X-ray generator can be moved up and down within the range in which it does not collide with the table. 
         [0022]    The X-ray radiography apparatus according to an eighth aspect is provided with a control device for controlling the traveling of the X-ray generator. When the X-ray generator is placed at a predetermined height or less, the control device controls the moving member in such a manner that the moving member is moved only within a second range. 
         [0023]    In the X-ray radiography apparatus according to the eighth aspect, the moving member can be moved only within the second range when the X-ray generator is placed at the predetermined height or less. It is therefore possible to prevent the X-ray generator from accidentally colliding with the table or the like. 
         [0024]    According to a X-ray radiography apparatus of the present invention, an X-ray generator can be moved to as low a position as possible, and the X-ray generator can be moved in a longitudinal direction of a table. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is a block diagram showing a construction of an X-ray radiography apparatus  100  for obtaining an X-ray penetrated image of a subject. 
           [0026]      FIG. 2  is a front perspective view showing constructions of a table  31  and a guide support post  41  employed in an embodiment. 
           [0027]      FIG. 3  is a back perspective view illustrating the constructions of the table  31  and the guide support post  41  employed in the embodiment. 
           [0028]      FIG. 4(   a ) is an enlarged front view depicting the constructions of the table  31  and the guide support post  41  in a state in which an X-ray tube unit  10  has been detached, and  FIG. 4(   b ) is a side view thereof. 
           [0029]      FIG. 5(   a ) is a top view showing the constructions of the table  31  and the guide support post  41 , and  FIG. 5(   b ) is a front view thereof. 
           [0030]      FIG. 6  is a flowchart for the transfer of the X-ray tube unit  10 . 
           [0031]      FIG. 7  shows a conventional X-ray radiography apparatus  200 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]      FIG. 1  is a block diagram showing a construction of X-ray CR (Computed Radiography) apparatus  100  for obtaining an X-ray penetrated image of a subject. Classified broadly, the present X-ray CR apparatus has an X-ray tube unit  10  which radiates X rays, a table  31  on which the subject lies down, a stand  32  which X-ray photographs the subject in its standing state, and an operation console  80 . The table  31  has a flat panel detector  34 - 1 . The stand  32  has a flat panel detector  34 - 2 . The flat panel detectors  34 - 1  and  34 - 2  are constituted of a scintillator, a light detector array, an X-ray exposure monitor, an electric substrate, etc. as principal constituent elements. The flat panel detector  34 - 2  mounted to the stand  32  is constructed so as to be movable up and down according to a photographed region of the subject. The flat panel detector  34 - 1  provided on the table  31  is constructed so as to be movable from side to side according to the photographed region of the subject, for example, the head or legs thereof. Incidentally, although the stand  32  is of a stationary type in  FIG. 1 , it may be constructed movably with tires added thereto. 
         [0033]    The operation console  80  has an X-ray power unit  84 , an image processor  87 , a motor driver  89 , etc. Image data transferred from the flat panel detector  34 - 1  or the flat panel detector  34 - 2  are sent to an X-ray data acquisition unit  86 . The collected X-ray data are image-processed at the image processor  87 . A display  81  displays an image-processed X-ray penetrated image thereon. There is no need to separately provide the flat panel detector  34 - 1  or the flat panel detector  34 - 2 . One flat panel detector  34  may be constructed so as to be alternately interchanged by a flexible cable. 
         [0034]    The X-ray tube unit  10  is held by the guide support post  41  and movable up and down in alignment with a diagnosed region of the subject as indicated by arrow A 2 . The X-ray power unit  84  and an X-ray controller  82  supply power of a suitable voltage current to an X-ray tube  11  of the X-ray tube unit  10 . The X-ray tube unit  10  further includes an unillustrated collimator for designating an irradiated field of view of an X-ray beam. The X-ray beam radiated from the X-ray tube  11  is applied onto the subject via the collimator. 
         [0035]    The guide support post  41  has a first drive motor  21  and a second drive motor  23 . The guide support post  41  is constructed so as to be moved by bearings  61  each corresponding to a sliding member, etc. as indicated by arrow A 1 . The first drive motor  21  is a motor for moving the X-ray tube unit  10  to a suitable height of the guide support post  41  and is controlled by a motor driver  89  lying within the operation console  80 . The second drive motor  23  is a motor for moving the guide support post  41  to a suitable position along the floor and is controlled by the motor driver  89  lying within the operation console  80 . It is not necessary to move the X-ray tube unit  10  or the guide support post  41  by electromotion. The X-ray tube unit  10  or the guide support post  41  may be constructed so as to be movable manually. 
         [0036]    Construction of moving device for X-ray tube unit.  FIG. 2  is a front perspective view showing the constructions of the table  31  and the guide support post  41  employed in the embodiment.  FIG. 3  is a back perspective view showing the constructions of the table  31  and the guide support post  41 . 
         [0037]    The table  31  is supported by a base or cradle  38 . Some of the motor driver  89  or the like in the operation console  80  may be built in the cradle  38 . 
         [0038]    A rail support side wall  51  is provided on the back side of the cradle  38 . At least one linear guide rail  53  is provided along the longitudinal direction of the table  31 . A movable stage  57  is provided so as to be combined with the linear guide rail  53 . The movable stage  57  is moved in the direction indicated by arrow A 1  under the rotation of an unillustrated ball screw by the second drive motor  23  (see  FIG. 1 ). When the second drive motor  23  is of a linear motor, the ball screw or the like becomes unnecessary. 
         [0039]    An off center arm  55  is attached to the movable stage  57 . The off center arm  55  has a structure which supports the guide support post  41 . In  FIG. 2 , the off center arm  55  has such a form as to be protruded in an X direction (transverse direction of the table  31 ) from the rail support side wall  51  and protruded on the right side (Z direction: longitudinal direction of the table  31 ) from the right edge of the rail support side wall  51 . That is, the off center arm  55  is formed in an L-shaped fashion as viewed from above. 
         [0040]    The off center arm  55  takes such a form as to be protruded from the right edge of the rail support side wall  51  to the right side to enable an X-ray tube unit carrier  45  supporting the X-ray tube unit  10  to be lowered to the utmost limit of the floor. When the off center arm  55  simply extends from the right edge of the rail support side wall  51  to its left side, the X-ray tube unit carrier  45  collides with the rail support side wall  51  as the X-ray tube unit carrier  45  approaches the floor. Therefore, the X-ray tube unit  10  cannot be lowered to the floor. 
         [0041]    Since the center of gravity of the off center arm  55  is placed in a position away from above the axial line of the linear guide rail  53 , a load is imposed on the linear guide rail  53 . Therefore, the off center arm  55  may preferably be made as light as possible. As is understandable from  FIGS. 2 and 3 , the off center arm  55  is held in a hollow structure and has such a structure that its strength and lightweight are made compatible. Incidentally, the off center arm  55  may take such a structure as to be combined directly with the linear guide rail  53  without providing the movable stage  57 . 
         [0042]    A tip portion of the off center arm  55  is coupled to its corresponding lower portion of the guide support post  41 . The guide support post  41  takes on a hollow structure for the purpose of its lightweight. The guide support post  41  has one or two or more vertical linear guide rails  43  around the outer periphery of the guide support post  41 . The X-ray tube unit carrier  45  is provided so as to be combined with the vertical linear guide rails  43 . The X-ray tube unit carrier  45  is moved up and down along the vertical linear guide rails  43 . An unillustrated ball screw is rotated by the first drive motor  21  (see  FIG. 1 ) so that the X-ray tube unit carrier  45  is moved in the direction indicated by arrow A 2 . The ball screw or the like becomes unnecessary when the first drive motor  21  is of a linear motor. Bearings, which slide in contact with the floor, are disposed below the guide support post  41  to support the self weights of the guide support post  41  and X-ray tube unit  10 . 
         [0043]    The X-ray tube unit carrier  45  comprises a base portion  45 - 1  combined with the vertical linear guide rails  43  and an arm portion  45 - 2  that extends in the X direction. The X-ray tube unit  10  is supported by the arm portion  45 - 2 . The X-ray tube unit  10  is provided in such a manner that the arm portion  45 - 2  thereof can be expanded and contracted and manually moved in the direction indicated by arrow A 3 . The expansion and contraction of the arm portion  45 - 2  may be position-controlled by a drive motor. The X-ray tube unit  10  is connected to the arm portion  45 - 2  by a ball joint structure and rotatable in a 360° direction with respect to an X axis. Further, the X-ray tube unit  10  is also rotatable even in a Y-axis or Z-axis direction. Therefore, the X-ray tube unit  10  is capable of applying an X-ray beam in an arbitrary direction according to the photographed region of the subject. 
         [0044]    Support constructions of guide support post  41  and off center arm  55 .  FIGS. 4(   a ) and  4 ( b ) are enlarged views showing support constructions of the off center arm  55  and the guide support post  41 .  FIG. 4(   a ) is an enlarged front view showing constructions of the table  31  and the guide support post  41 , and  FIG. 4(   b ) is a side view thereof. Incidentally, the X-ray tube unit  10  is in a detached state in  FIG. 4(   a ) to make it easy to see the bearings  61  used as the sliding members. 
         [0045]    In order to lower the X-ray tube unit  10  to as low a position as possible, the off center arm  55  is not disposed on the Y axis of the linear guide rail  53 . Therefore, it is difficult to support the self weights of the X-ray tube unit  10 , the guide support post  41  and the off center arm  55  in a cantilevered state. Accordingly, the guide support post  41  is provided with the bearings  61  corresponding to the sliding members at locations where they slide in contact with the floor of the guide support post  41 . The bearings  61  are constructed so as to support the self weights of the X-ray tube unit  10 , the guide support post  41  and the off center arm  55  and to be movable in the Z direction. When the off center arm  55  adopts such a structure that it supports all weights of the guide support post  41 , the bearings  61  may be mounted to the off center arm  55 . 
         [0046]      FIG. 5(   a ) is a top view showing the constructions of the table  31  and the guide support post  41 , and  FIG. 5(   b ) is a front view thereof.  FIG. 6  is a flowchart for the transfer of the X-ray tube unit  10 . Since the X-ray tube unit  10  can be lowered to the floor unlike the conventional apparatus, the X-ray tube unit carrier  45  collides with the table  31  or the rail support side wall  51 . In order to prevent this collision before happens, such an operation as to be described below is performed upon the transfer or traveling of the X-ray tube unit  10 . 
         [0047]    In  FIG. 5 , a position sensor S 1  is disposed between the rail support side wall  51  and the movable stage  57 . The position sensor S 1  is provided so as to be capable of grasping or identifying the position of the movable stage  57 . As shown in  FIG. 5(   a ), the position sensor S 1  may preferably identify whether the movable stage  57  is disposed in either a range W 1  or a range W 2 . 
         [0048]    A position sensor S 2  is disposed between the guide support post  41  and the X-ray tube unit carrier  45 . The position sensor S 2  is provided so as to be capable of identifying the position of the X-ray tube unit carrier  45 . As shown in  FIG. 5(   b ), the position sensor S 2  may preferably identify whether the X-ray tube unit carrier  45  is disposed in either a range H 1  or a range H 2 . 
         [0049]    A signal from the position sensor S 1  or the position sensor S 2  is sent to a control device  25 . The control device  25  transmits a control signal to the motor driver  89 , based on the signal, so that the motor driver  89  drives the first drive motor  21  and the second drive motor  23 . 
         [0050]    Control on the transfer of the X-ray tube unit  10  will be explained using a flowchart shown in  FIG. 6 . 
         [0051]    At Step S 11  of  FIG. 6 , the position sensor S 2  confirms the position of the movable stage  57 . A signal from the position sensor S 2  is transmitted to the control device  25 . 
         [0052]    At Step S 12 , the position sensor S 1  confirms the position of the X-ray tube unit carrier  45 . A signal from the position sensor S 1  is also transmitted to the control device  25 . 
         [0053]    At Step S 13 , the control device  25  determines whether the movable stage  57  is placed in either the range W 1  or W 2 . If it is found that the movable stage  57  is placed in the range W 1 , then the control device  25  proceeds to Step S 14 . If it is found that the movable stage  57  is placed in the range W 2 , then the control device  25  proceeds to Step S 19 . 
         [0054]    At Step S 14 , the control device  25  determines whether the X-ray tube unit carrier  45  is disposed in either the range H 1  or H 2 . If it is found that the X-ray tube unit carrier  45  is placed in the range H 1 , then the control device  25  proceeds to Step S 15 . If it is found that the X-ray tube unit carrier  45  is placed in the range H 2 , then the control device  25  proceeds to Step S 17 . 
         [0055]    At Step S 15 , the movable stage  57  stops. The second drive motor  23  may be supplied with a brake signal to stop the movable stage  57 . Alternatively, the movable stage  57  may be provided with an electromagnetic stopper to make it unable for the movable stage  57  to move. 
         [0056]    At Step S 16 , the control device  25  controls the X-ray tube unit carrier  45  such that it gets out of the range H 1  because the X-ray tube unit carrier  45  is within the range H 1  accidentally. That is, the X-ray tube unit carrier  45  can travel only in the direction of a position HE. 
         [0057]    At Step S 17 , the X-ray tube unit carrier  45  is capable of moving within the range H 2 . However, the control device  25  controls the X-ray tube unit carrier  45  in such a manner that it does not enter the side below the position HE, i.e. it does not fall within the range H 1 . The guide support post  41  is provided with an electromagnetic stopper, which limits the traveling or transfer of the X-ray tube unit carrier  45  to the range H 2 . 
         [0058]    At Step S 18 , the movable stage  57  is movable even within both of the range W 1  and the range W 2 . 
         [0059]    Next, when the movable stage  57  is placed in the range W 2 , the X-ray tube unit carrier  45  is movable even within both the ranges H 1  and H 2  at Step S 19 . The X-ray tube unit carrier  45  is movable to nearly the floor. Thus, the X-ray tube unit  10  can apply an X-ray beam to regions below the knees of the subject in a state in which the subject is standing. 
         [0060]    At Step S 20 , the control device  25  determines whether the X-ray tube unit carrier  45  is disposed in either the range H 1  or H 2 . If it is found that the X-ray tube unit carrier  45  is placed in the range H 1 , then the control device  25  proceeds to Step S 21 . If it is found that the X-ray tube unit carrier  45  is placed in the range H 2 , then the control device  25  proceeds to Step S 18 . When the control device  25  proceeds to Step S 18 , the movable stage  57  is movable even within both of the ranges W 1  and W 2  as mentioned above. 
         [0061]    At Step S 21 , the movable stage  57  is movable within the range H 2 . In  FIG. 5(   a ), however, a stopper is operated to prevent the movable stage  57  from being moved from a position WE to the left side. Thus, the X-ray tube unit carrier  45  is prevented from accidentally colliding with the rail support side wall  51  or the table  31 . 
         [0062]    Although the longitudinal direction is divided into the range W 1  and the range W 2  in  FIG. 5  or  6 , it may be divided into three or more according to the length of the table  31  or the length of the rail support side wall  51 . The traveling or moving range of the X-ray tube unit carrier  45  may also be divided into three or more without being divided into the ranges H 1  and H 2 . 
         [0063]    Although the medical X-ray CR apparatus  100  has been described in the present embodiment, the present invention can be applied even to an industrial X-ray CR apparatus to enable X-ray radiography with respect to a target member from various angles.