Abstract:
Depth diaphragm for an x-ray device, which diaphragm has a plurality of adjustable diaphragm blades ( 1 ) for displaying an area being examined, which blades ( 1 ) can be moved in such a way that said area being examined can be displayed asymmetrically.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority to the German application No. 10 2004 004 629.8, filed Jan. 29, 2004 which is incorporated by reference herein in its entirety.  
       FIELD OF INVENTION  
       [0002]     The invention relates to a depth diaphragm for an x-ray device, which diaphragm has a plurality of adjustable diaphragm blades for displaying an area being examined, which blades can be moved in such a way that said area being examined can be displayed asymmetrically.  
       BACKGROUND OF INVENTION  
       [0003]     Depth diaphragms are components of x-ray equipment and serve to variably restrict the bundle of rays to the necessary field size. The undesired portions of the rays are absorbed by the diaphragm blades, which are usually made of lead. To set the depth diaphragm, the desired field size can be simulated by means of a light bundle. X-ray equipment is usually fitted with depth diaphragms having two pairs of lead blades for adjusting the height and width of the image display. Said pairs of lead blades are controlled symmetrically with respect to the center of the detector and isocentrically with respect to the x-ray tube. The plate-shaped diaphragm blades cannot, however, be enlarged at will as that would also increase the size of the depth diaphragm, resulting in, for instance, angulation limiting on a C-arch of the x-ray device.  
       SUMMARY OF INVENTION  
       [0004]     It is therefore an object of the invention to provide a depth diaphragm offering expanded setting options and enabling the area being examined to be displayed flexibly.  
         [0005]     This object is achieved by the claims.  
         [0006]     The depth diaphragm according to the invention offers expanded setting options that eliminate the customary restriction to symmetrical settings. Each diaphragm blade can in particular be controlled independently. Each such blade of the depth diaphragm according to the invention can for this purpose be assigned a drive, preferably an electric motor.  
         [0007]     The depth diaphragm according to the invention allows the area being examined to be displayed far more flexibly compared to conventional devices. The depth diaphragm and the x-ray device overall are far easier to set and operate because far more setting options are available. This flexibility is particularly advantageous when there is cause for a patient not to be examined in a standard position.  
         [0008]     Being attached to each other in an articulated fashion, the individual blade sections can be accommodated in a space saving manner in a depth diaphragm housing.  
         [0009]     A further improvement in the depth diaphragm according to the invention can be achieved by providing the possibility of winding a diaphragm blade on a drum that can be controlled by the drive, in particular by the electric motor. In this embodiment of the invention each diaphragm blade can be wound on a drum. To set the area being examined, the relevant drum drive is activated so that the respective diaphragm blade wound on the drum is moved into said area being examined. If a total of four diaphragm blades are provided arranged at right angles to each other, opposite drums can be arranged in a plane so that the drums will not obstruct each other.  
         [0010]     The diaphragm blades can according to the invention be flexible. Each diaphragm blade can advantageously be moved separately.  
         [0011]     According to a second, alternative embodiment of the invention the depth diaphragm can have two pairs of diaphragm blades that can be individually moved in the same direction and are arranged in one plane above the other. The essential feature here is that each diaphragm blade can be separately controlled and moved so that the diaphragm blades can be positioned asymmetrically. It is thus of practical advantage for each diaphragm blade to be connected to its own drive, for example to an electric motor. The are a being examined can in this way be displayed asymmetrically even with plate shaped diaphragm blades.  
         [0012]     The diaphragm blades can preferably be made of lead, but it is also possible to embed them in a plastic material or coat them with a plastic material.  
         [0013]     It is of particular practical advantage if the depth diaphragm according to the invention can be or is coupled to an operating device by means of which each diaphragm blade can be actuated separately. It can also be provided for the ope rating device to have an input device such as a joystick or mouse.  
         [0014]     The invention further relates to an x-ray device characterized in having a depth diaphragm of the type described. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     Further advantages and specifics of the invention will be explained with the aid of exemplary embodiments and with reference to the drawings. The drawings are schematic representations showing the following:  
         [0016]      FIG. 1  is a first exemplary embodiment of the invention having a diaphragm blade of a depth diaphragm according to the invention which blade is wound on a drum;  
         [0017]      FIG. 2  is a top view of a depth diaphragm according to the invention containing four drums;  
         [0018]      FIG. 3  is a lateral view of the depth diaphragm shown in  FIG. 2 ;  
         [0019]      FIG. 4   a  is a second exemplary embodiment of the invention having two pairs of diaphragm blades arranged in one plane above the other;  
         [0020]      FIG. 4   b  illustrates the diaphragm blades shown in  FIG. 4   a  in a second position, and  
         [0021]      FIG. 4   c  illustrates the diaphragm blades shown in  FIG. 4   a  in a third position. 
     
    
     DETAILED DESCRIPTION OF INVENTION  
       [0022]      FIG. 1  shows a diaphragm blade  1  made of lead or a lead alloy and wound onto a drum  2 . The drum  2  is connected via a shaft  3  to a schematically represented motor  4  for rotating the drum  2  in both directions.  
         [0023]     The diaphragm blade  1  is laterally ducted in guide rails  5 ,  6  so that the diaphragm blade  1  is wound from the drum  2  or onto the drum  2  parallel to the guide rails  5 ,  6  when the motor  4  has been activated. The directions of motion of the diaphragm blade  1  are indicated in  FIG. 1  by the double arrow  7 .  
         [0024]     The diaphragm blade  1  is sufficiently flexible to be able to be wound onto the drum  2 . On the other hand the lead coating is sufficiently thick to shield off and absorb the undesired radiation. To facilitate winding onto the drum  2 , the diaphragm blade  1  is embodied in the manner of a roller shutter.  
         [0025]      FIG. 2  is a top view of a depth diaphragm  8  containing four drums  2 ,  11 . The drums correspond to the drum  2  shown in  FIG. 1 , with in each case two drums  2  or, as the case may be,  11  being located opposite each other in pairs. Each of the drums  2 ,  11  is provided with a drive that is shown schematically and embodied as an electric motor  4 ,  12 . Also shown in  FIG. 2  are the two pairs of guide rails  5 ,  6  and  9 ,  10 . Flexible diaphragm blades not shown in the figure are wound onto the drums  2 ,  11 .  
         [0026]      FIG. 3  is a lateral view of the depth diaphragm  8  shown in  FIG. 2 . As can be seen in  FIG. 3 , the pairs of drums  2  and  11  are in each case located opposite each other in pairs, with the two pairs of drums  2 ,  11  being arranged in different, parallel planes. The two electric motors  4  of the top pair of drums  2  can be controlled separately from each other so that the diaphragm blade wound on the left-hand drum  2  is moved to the right or left when the left-hand motor  4  in  FIGS. 2 and 3  has been activated. When the electric motor  4  on the right in  FIGS. 2 and 3  has been activated, the diaphragm blade wound on the right-hand drum  2  is analogously moved to the left or right to control the width of the image display. To move the drums  11 , each drum  11  has been assigned an electric motor  12 .  
         [0027]     The bottom pair of drums  11  has been turned through 90° relative to the top pair of drums  2  but is otherwise controlled in the same manner. The respective drum  11  is made to rotate on activation of one of the electric motors  12  so that the diaphragm blade wound on the respective drum is moved in the vertical direction in  FIG. 2  so that the height of the image display is controlled, with the diaphragm blades being ducted in the guide rails  9 ,  10 .  
         [0028]      FIG. 4   a  shows a second exemplary embodiment of the invention having two pairs of diaphragm blades arranged in one plane above the other.  
         [0029]     The top pair consists of the diaphragm blades  13 ,  14  embodied as plate-shaped lead blades. Each of the diaphragm blades  13 ,  14  can be separately positioned via a drive (not shown). Arranged in a second plane below the diaphragm blades  13 ,  14  are diaphragm blades  15 ,  16  having the same physical structure as the diaphragm blades  13 ,  14 . The diaphragm blades  15 ,  16  can also each be positioned separately in the direction indicated by the double arrow  18 . This means that the e-ray beam  17  can only impinge on areas not obscured either by the top pair of diaphragm blades  13 ,  14  or by the bottom pair  15 ,  16 . The setting options are multifarious as the diaphragm blades can be separately positioned.  
         [0030]      FIG. 4   b  illustrates the diaphragm blades shown in  FIG. 4   a  in a second position. While the top pair of diaphragm blades  13 ,  14  has remain unchanged compared to  FIG. 4   a , the diaphragm blade  15  belonging to the bottom pair of blades has been moved toward the second diaphragm blade  16  so that the area permeable to the x-ray beam  17  has been reduced in size.  
         [0031]      FIG. 4   c  illustrates the diaphragm blades shown in  FIG. 4   a  in a third position. The top two diaphragm blades  13 ,  14  have each been moved outward, resulting in a large space through which the x-ray beam  17  enters. The diaphragm blade  15  belonging to the bottom pair of diaphragm blades has been moved aside like the diaphragm blade  13  so as to be situated exactly below the diaphragm blade  13 . The second diaphragm blade  16  belonging to the bottom pair of diaphragm blades is located in the space formed by the top diaphragm blades  13 ,  14 . The x-ray beam  17  can therefore only impinge on the object being examined through the two areas left and right of the diaphragm blade  16 .  
         [0032]     The positioning of the diaphragm blades shown in  FIG. 4   c  would be an advantageous choice for examining a patient&#39;s legs, for example. The area in the center of the image will be masked out by moving the diaphragm blade  16  into the space between the diaphragm blades  13  and  14 .  
         [0033]     A factor common to all embodiments is that they can be used in conjunction with large-area detectors without increasing the size of the depth diaphragm.