Abstract:
With a view to attaining both easiness of position adjustment and sureness of position holding, a patient supporting apparatus comprises an arm for supporting a patient, the arm comprising a horizontal arm portion and a vertical arm portion, a rail for supporting the arm movably in a direction perpendicular to the horizontal arm portion and the vertical arm portion, and a brake for preventing movement of the arm along the rail by utilizing a moment of rotation with the vertical arm portion of the arm being as an axis.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a patient supporting apparatus and a medical image photographing apparatus. Particularly, the present invention is concerned with an apparatus for supporting a patient during medical image photographing and a medical image photographing apparatus having the patient supporting apparatus.  
         [0002]     When the body of a patient is photographed sideways by means of an X-ray photographing apparatus, the photographing is performed with both arms of the patient raised. For supporting both arms of the patient there is a need to use a supporting apparatus. The supporting apparatus is provided with a vertical arm portion mounted on the back side of an X-ray receiving panel and a horizontal arm portion projecting toward the patient side from an upper end of the vertical arm portion. The horizontal arm portion is convenient for the patient to grasp with both hands. A vertical arm mounting mechanism results in that the position of the vertical arm can be adjusted in a stepless manner in a direction parallel to the X-ray receiving panel (see, for example, Patent Literature 1).  
         [0003]     [Patent Literature 1] U.S. Patent Application Laid Open No. 2003/0202635 (pp. 4-5,  FIG. 8 )  
         [0004]     For the vertical arm mounting mechanism in the above patient supporting apparatus it is required that the position of the vertical arm be easily adjustable and that an accurately adjusted position be able to be held positively. However, both requirements are generally difficult to be satisfied at the same time. More particularly speaking, if the position adjustment is made easier, the vertical arm becomes easier to be moved by the patient during photographing, while if the vertical arm portion is made difficult to be moved, it will become difficult to effect position adjustment.  
       SUMMARY OF THE INVENTION  
       [0005]     Therefore, it is an object of the present invention to provide a patient supporting apparatus capable of realizing both easiness of position adjustment and sureness of position holding and also provide a medical image photographing apparatus having such a patient supporting apparatus.  
         [0006]     (1) In one aspect of the present invention, for solving the above-mentioned problem, there is provided a patient supporting apparatus comprising an arm for supporting a patient, the arm comprising a horizontal arm portion and a vertical arm portion; a rail for supporting the arm movably in a direction perpendicular to the horizontal arm portion and the vertical arm portion; and a brake for preventing movement of the arm along the rail by utilizing a moment of rotation with the vertical arm portion of the arm being as an axis.  
         [0007]     (2) In another aspect of the present invention, for solving the above-mentioned problem, there is provided a medical image photographing apparatus comprising a patient supporting means and a photographing means for photographing a medical image of a patient supported by the patient supporting means, the patient supporting means comprising an arm supporting a patient and comprising a horizontal arm portion and a vertical arm portion; a rail for supporting the arm movably in a direction perpendicular to the horizontal arm portion and the vertical arm portion; and a brake for preventing movement of the arm along the rail by utilizing a moment of rotation centered on the vertical arm portion of the arm.  
         [0008]     For the simplification of construction it is preferable that the brake be provided with a sub-rail parallel to the rail and a brake shoe adapted to be pressed against the sub-rail by utilizing the moment of rotation.  
         [0009]     For simplifying the structure of the brake shoe it is preferable that the sub-rail be a grooved rail. Further, it is preferable for the brake shoe to have a fitting portion for fitting in the groove of the sub-rail. This is preferable because braking is applied the brake by utilizing friction induced between the fitting portion and an inner wall of the groove.  
         [0010]     It is preferable that there is a driven gear on the brake shoe, a rotating force based on the moment of rotation is imparted to the driven gear. Therefore, this is preferable because the moment of rotation is transferred effectively. For the same reason it is preferable that there is a driven gear on the vertical arm portion of the arm, for imparting the rotating force to the driven gear.  
         [0011]     For supporting a patient properly it is preferable that the horizontal arm portion of the arm be for the patient to grasp. It is preferable that the horizontal arm portion of the arm be for the patient to grasp with his or her arms raised. This is preferable for preventing the patient&#39;s arms from blocking the X-ray within the photographing visual field.  
         [0012]     According to the present invention in the above aspects, the patient supporting apparatus comprises an arm for supporting a patient, the arm comprising a horizontal arm portion and a vertical arm portion; a rail for supporting the arm movably in a direction perpendicular to the horizontal arm portion and the vertical arm portion; and a brake for preventing movement of the arm along the rail by utilizing a moment of rotation centered on the vertical arm portion of the arm. With this construction, when the apparatus supports a patient, a brake is applied the brake by a moment of rotation which acts on the vertical arm portion through the horizontal arm portion, whereby the sureness of the position holding is ensured, while when the apparatus does not support a patient, a brake is not applied the brake and the vertical arm portion can be moved easily along the rail. Thus, it is possible for the patient supporting apparatus to realize the functions that both easiness of position adjustment and sureness of position holding, and a medical image photographing apparatus having such a patient supporting apparatus.  
         [0013]     Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  illustrates a medical image photographing apparatus according to an example of the best mode for carrying out the present invention.  
         [0015]      FIG. 2  illustrates a patient supporting apparatus according to another example of the best mode for carrying out the present invention.  
         [0016]      FIG. 3  is a perspective view showing a partial construction of the patient supporting apparatus.  
         [0017]      FIG. 4  is an exploded view showing a partial construction of the patient supporting apparatus.  
         [0018]      FIG. 5  is an exploded view showing a partial construction of the patient supporting apparatus.  
         [0019]      FIG. 6  is a perspective view showing a partial construction of the patient supporting apparatus. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]     A best mode for carrying out the present invention will be described below with reference to the accompanying drawings, provided the invention is not limited to the best mode.  FIG. 1  shows the construction of an X-ray photographing apparatus which is an example of the best mode for carrying out the invention. With the construction of this apparatus, there is shown an example of the best mode for carrying out the invention related to the medical image photographing apparatus.  
         [0021]     In the X-ray photographing apparatus, as shown in the same one figure, X-ray is radiated from an X-ray tube  2  to a patient  4 , then transmitted X-ray is received by an X-ray receiving panel  6 , and a received light signal is processed by a photographing console  8  to reconstruct a perspective image of the patient  4 . The reconstructed perspective image is displayed on a display  802  of the photographing console  8 . The portion comprising the X-ray tube  2 , X-ray receiving panel  6  and photographing console  8  is an example of the photographing means defined in the present invention  
         [0022]     The patient  4  stands up sideways of the X-ray receiving panel  6  and X-ray is radiated sideways of the patent. The patient assumes a posture that both arms are raised to grasp a patient supporting apparatus  10  located above the head of the patient and to thereby prevent both arms from being present within a visual field for photographing. The patient supporting apparatus  10  is an example of the patient supporting means defined in the present invention.  
         [0023]      FIG. 2  is a perspective view showing the construction of the patient supporting apparatus  10 , together with the X-ray receiving panel  6 . The patient supporting apparatus  10  is an example of the best mode for carrying out the present invention. With the construction of this apparatus, there is shown an example of the best mode for carrying out the invention related to the patient supporting apparatus.  
         [0024]     As shown in the same figure, a rear side of the X-ray receiving panel  6  is mounted on a front end of a cross beam  604  which extends from a support post  602 . A front side of the X-ray receiving panel  6  confronts a patient. The patient supporting apparatus  10  is mounted on the end portion of the cross beam  604  which is located on the side opposite to the panel  6 .  
         [0025]     The patient supporting apparatus  10  has a generally L-shaped arm comprising a horizontal arm portion  102  and a vertical arm portion  104 . The horizontal arm portion  102  extends from an upper end of the vertical arm portion  104 , passes over the X-ray receiving panel  6  and projects to the front side of the panel  6 . A base portion of the vertical arm portion  104  is supported by a base assembly  106 . The L-shaped arm comprising the horizontal arm portion  102  and the vertical arm portion  104  is an example of the arm in the present invention. The horizontal arm portion  102  is an example of the horizontal arm portion defined in the present invention and the vertical arm portion  104  is an example of the vertical arm portion defined in the present invention.  
         [0026]     FIGS.  3  to  6  show the structure of the base portion of the vertical arm portion  104  and that of the base assembly  106 , of which  FIG. 3  is a perspective view from a front side,  FIGS. 4 and 5  are partially cut-away exploded views, and  FIG. 6  is a perspective view from a rear side.  
         [0027]     As shown in these figures, the base assembly  106  includes a base member  162 , a main rail  164  and a sub-rail  166  both secured to the base member  162 , and a front plate  168 . The main rail  164 , the sub-rail  166  and the front plate  168  are parallel to one another and have a longitudinal direction perpendicular to the horizontal arm portion  102  and the vertical arm portion  104 . The main rail  164  is an example of the rail defined in the present invention.  
         [0028]     The main rail  164  has an H-shaped section and one side face thereof is secured to the base member  162 . The sub-rail  166  has a groove formed in an upper surface thereof and is secured to the base member  162  so that the groove faces up. The front plate  168  serves as a bumper plate for the base assembly  106 .  
         [0029]     The base portion of the vertical arm portion  104  includes a slider  142  engaged with the main rail  164 , a main shaft  144  mounted to the slider  142 , a collar  146  fitted loosely on the main shaft, a brake shoe  148  fitted loosely on the collar  146 , and a stud  150  mounted on the collar  146 . The vertical arm portion  104  is secured to the stud  150 .  
         [0030]     The main shaft  144  is a central shaft of the vertical arm portion  104  and extends vertically. The collar  146 , the brake shoe  148  and the stud  150  are coaxial with the main shaft  144 . The brake shoe  148  has an L-shaped fitting portion  482  for fitting in the groove of the sub-rail  166 . The brake shoe  148  also has a gear  484  on an upper surface thereof. The gear  484  is in mesh with a gear  504  mounted on a lower surface of the stud  150 .  
         [0031]     Since the base portion of the vertical arm portion  104  and the base assembly  106  have such structures, when the horizontal arm  102  is pushed or pulled in the horizontal direction as indicated with arrow A as shown in  FIG. 2 , a moment of rotation with the axis of the vertical arm  104  being as a center acts on the vertical arm portion.  
         [0032]     This moment of rotation, which is indicated with arrow C in  FIG. 6 , is transmitted as such a moment of rotation as indicated with arrow D to the brake shoe  148  through the engagement between the gear  504  on the lower surface of the stud  150  and the gear  484  on the upper surface of the brake shoe  148 .  
         [0033]     With such a moment of rotation, a side face of the fitting portion  482  of the brake shoe  148  is pressed against a side face of the groove within the sub-rail  166 , resulting in that a frictional force between the two increases. Since this increase in frictional force inhibits movement of the slider  142 , the vertical arm portion  104  cannot move.  
         [0034]     A pulling force of a pushing force acts in arrow A direction on the horizontal arm portion  102  when the patient grasps the horizontal arm  102 . However, in such a case, movement of the vertical arm portion  104  is inhibited as above and the patient supporting apparatus  10  is sure to be held in position.  
         [0035]     The portion comprising the sub-rail  166  and the brake shoe  148  is an example of the brake defined in the present invention. The sub-rail  166  is an example of the sub-rail defined in the present invention. The brake shoe  148  is an example of the brake shoe defined in the present invention.  
         [0036]     The gear  504  is an example of the drive gear defined in the present invention. The gear  484  is an example of the driven gear defined in the present invention.  
         [0037]     Since the brake includes the sub-rail  166  parallel to the main rail  164  and the brake shoe  148  adapted to be pushed against the sub-rail by utilizing a moment of rotation, it is possible to simplify its construction.  
         [0038]     Since the sub-rail  166  is a grooved rail, it is possible to simplify the structure of the brake shoe. Since the brake shoe  148  has the fitting portion  482  for fitting in the groove of the sub-rail  166 , it is possible to apply the brake by utilizing friction inducted between the fitting portion and the inner wall of the groove.  
         [0039]     Since the brake shoe  148  has the driven gear  484  onto which a rotating force generated by a moment of rotation is imparted, it is possible to receive the moment of rotation effectively. Since the stud  150  with the vertical arm portion  104  secured thereto is provided with the drive gear  504  which imparts the rotating force to the driven gear  484 , it is possible to enable the rotational moment to be transferred effectively.  
         [0040]     Since the horizontal arm portion  102  is for a patient to grasp, it is possible to support the patient properly. Further, since the horizontal arm portion  102  is for to be grasped by the patient&#39;s raised arms, it is possible to prevent the arms from being present within the visual field for photographing.  
         [0041]     For changing the position of the patient supporting apparatus  10 , a horizontal force is applied to the vertical arm portion  104  as indicated with arrow B in  FIG. 2 . At this time, a moment of rotation centered on the vertical arm portion  104  is not generated, therefore a braking force can not be generated by the brake shoe  148 . Consequently, the slider  142  can be moved smoothly and hence it is easy to adjust the patient supporting apparatus  10 .  
         [0042]     Many widely different embodiments of the invention may be configured without departing from the spirit and the scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments described in the specification, except as defined in the appended claims.