Abstract:
Radiation image capture apparatus, in particular x-ray apparatus, comprising a radiation source and a radiation receptor, between which an examination object is to be positioned for image capture, a laterally closed apron-like radiation absorption apparatus which can be moved in the direction of the examination object to absorb scattered radiation emitted by the examination object being pro-vided at the radiation source and/or at the radiation receptor.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims priority to the German Application No. 10 2005 006 894.2, filed Feb. 15, 2005 which is incorporated by reference herein in its entirety. 
   FIELD OF INVENTION 
   The invention relates to a radiation image capture apparatus, in particular an x-ray apparatus, comprising a radiation source and a radiation receptor, between which an examination object is to be positioned for image capture. 
   BACKGROUND OF INVENTION 
   During radiation image capture, for example an x-ray examination, a point radiation source emits the radiation applied to a patient, for example the x-ray radiation. After this radiation has passed through the patient, it strikes the receptor, for example a solid-state radiation detector, an x-ray amplifier or the like. While the radiation is passing though the patient, scatter processes occur, in other words the x -ray radiation which is penetrating or has penetrated the patient is scattered in all directions, so that scattered radiation is radiated by the patient into the environment. This scattered radiation can be a hazard to persons standing in the vicinity of the radiation image capture apparatus, such as the doctor providing treatment or the medical personnel. To suppress this scattered radiation the radiation receptor, thus for example the image amplifier, a film-membrane system, the solid-state radiation detector etc. is often brought as close as possible to the patient. However, this reduces the quality of the image, since a relatively large amount of the x-ray radiation emerging on the patient near the radiation receptor is captured because said radiation receptor is positioned directly on the patient, it being known that this scattered radiation does not contain any image information in contrast to the primary radiation. To counter this, scattered radiation grids are used, which are provided at the capture unit. Another known technique is the “air gap” technique, in which a relatively large distance is left between the patient and the radiation receptor, for example between 20 and 30 cm. A considerable proportion of the scattered radiation emerging on the patient to the radiation receptor side misses the receptor because of the higher solid angle divergence, and thus is not processed by it because of the higher solid angle divergence. The image quality is improved, but the aforementioned radiation hazards for personnel present still occur. However, a radiation hazard results not just from scattered radiation, which essentially emerges on the side of the patient facing the radiation receptor, but also as a result of scattered radiation emerging forward, in other words toward the radiation source, which is likewise harmful for the personnel providing treatment, there generally being a relatively large distance here between radiation source and the examination object. 
   SUMMARY OF INVENTION 
   An object of the invention is thus to specify a way of enabling the quantity of scattered radiation emerging into the environment to be reduced. 
   To achieve this object it is provided according to the invention in the case of radiation image capture of the type mentioned in the introduction that a laterally closed radiation absorption apparatus which can be moved in the direction of the examination object be provided at the radiation source and/or at the radiation receptor to absorb scattered radiation emitted by the examination object. 
   The inventive apron-like radiation absorption apparatus is particularly advantageously used to close the space between the patient and for example the radiation receptor, thus the air gap mentioned in the introduction, thus virtually forming a radiation tunnel between the patient and the radiation receptor. Any scattered radiation which in this case misses the radiation receptor necessarily strikes the radiation absorption apparatus and is absorbed thereby, and thus can no longer emerge into the environment and hence into personnel standing nearby. In corresponding fashion a radiation absorption apparatus running from the radiation source to the patient can also alternatively or additionally be provided. This also virtually forms a radiation tunnel, the scattered radiation emitted in the forward direction here too being absorbed by the radiation absorption apparatus. The radiation absorption apparatus itself is closed at the sides, producing overall a structure closed on all sides which can collect scattered radiation to a very high degree. 
   To enable the radiation receptor or the radiation source to be adjusted in respect of the examination object, said adjustment differing in accordance with the examination or type of examination being performed, the radiation absorption apparatus can expediently be moved in the direction of the examination object. This means it is possible to span distances of varying size since the radiation absorption apparatus can be correspondingly moved and thereby positioned. The doctor is thus subject to no restrictions when capturing images as a result of the arrangement of the radiation absorption apparatus. 
   Thus the inventive radiation image capture apparatus both permits good-quality image capture, since the air gap technique can be used straight away, and achieves maximum protection for nearby personnel against scattered radiation, a high standard of protection being produced if a radiation absorption apparatus is provided only at the radiation receptor, and virtually complete “radiation encapsulization” being achieved if two scattered radiation apparatuses are used in the radiation source and at the radiation receptor. 
   The radiation absorption apparatus can preferably be moved linearly in respect of the radiation source or the radiation receptor, corresponding linear guides being provided, in or on which the radiation absorption apparatus is guided. It can also easily be relocated in respect of the relevant equipment. 
   According to a first embodiment of the invention the radiation absorption apparatus can here be rigid and supported at the radiation source and at the radiation receptor in its entirety to enable it to be relocated laterally. The radiation absorption apparatus is for example rectangular or box -shaped, such a shape being provided for example by rectangular solid-state detectors. The shape of the radiation absorption apparatus is geared to the basic shape of the equipment at which it is arranged. In addition, for example, in the case of a round radiation receptor a hollow cylindrical design of the radiation absorption apparatus is also conceivable. In each case it is designed to be rigid, which means it is relocated linearly in its entirety in respect of the relevant device. 
   Alternatively the radiation absorption apparatus can also consist of sections linked so that they move together and can be relocated in respect of one another, which in the retracted position are arranged essentially in parallel next to one another and in the extended position are arranged one behind the other. The radiation absorption apparatus consists in this embodiment virtually of several mutually linked segments or similar sections. For example, in the case of a rectangular or box-shaped embodiment of the radiation absorption apparatus three such sections are provided on each wall, which can be moved one after the other and taken apart when the radiation absorption apparatus is extended. Alternatively to this embodiment it is also conceivable that the radiation absorption apparatus can be collapsed or folded up, the ability to collapse like an accordion being expedient here both in the case of a rectangular or box-shaped embodiment and of a hollow cylindrical round embodiment. 
   Alternatively to the laterally closed, single-part shape of the radiation absorption apparatus it is also conceivable to form it from a plurality of separate swivel-mounted sections, which in order to capture an image can be swiveled into a position in which a laterally closed shape is produced. Such an embodiment is provided for example for a radiation absorption apparatus arranged at the radiation source, since from time to time account must be taken here of the radiation array which increases with the increasing distance from the radiation source. In each case the individual swivel sections are designed so that they laterally sufficiently overlap even with a relatively large beam angle, so that a closed shape is produced. 
   A particularly expedient development provides that the radiation absorption apparatus can be automatically moved using at least a drive motor that can be controlled by means of a control apparatus. If the radiation absorption apparatus is arranged at the radiation receptor for example, in particular a solid-state radiation detector, it can be relocated by the motor in respect of the detector. In this connection either a separate motor can be used, or recourse can be had to a motor frequently provided here which serves to move the detector in respect of the patient. 
   In this connection it is expedient if at least one sensor is provided to detect the position of the radiation absorption apparatus relative to the examination object, which communicates with the control apparatus, which controls the movement operation as a function of position detection. It is hereby ensured that the movement of the radiation absorption apparatus is terminated at the correct time and that it thus is not extended too far and does not strike the patient. The sensor continuously detects the relative position to the examination object, so that straight away the correct position is detected and the movement operation can be terminated. 
   If the radiation source and the radiation receptor are arranged on a moveable C-arm, it is expedient if a radiation absorption apparatus when detecting an intended or commenced movement of the C-arm can be moved via the control apparatus away from the examination object in order to avoid a collision therewith and if necessary can again be moved automatically toward the examination object after reaching a new capture position. The radiation source and the radiation receptor can be swiveled freely in known manner via the C-arm relative to the examination object. If an image capture was undertaken in a first position in which the one or both radiation absorption apparatuses were optimally positioned, it must be ensured that when the C-arm is turned on a collision between the radiation absorption apparatus and the patient is avoided. To this end, as soon as it is detected that a movement is to be initiated or has already been initiated, the respective radiation absorption apparatus is moved a short distance away from the patient, so that there is a sufficient swivel or movement clearance. On reaching the new position the respective radiation absorption apparatus is preferably again moved automatically into the optimum position, so that the image capture operation can start immediately. 
   The radiation absorption apparatus itself can for example have band—or plate-shaped lead, which is accommodated in a sheath, to absorb radiation. This applies for all embodiments described. In the case of a rigid radiation absorption apparatus it is possible to provide only a relatively large-surface band-shaped lead element which extends fully circumferentially over the entire length of the absorption apparatus. In the case of a collapsible apparatus, a plurality of separate band—or plate-shaped lead elements is provided for example, which depending on the embodiment are connected to one another so as to move together or are in another way positioned in respect of one another. Preferably the one or more lead elements are accommodated in a suitable sheath, and preferably have a thickness of approx. 1 mm, this strength of lead being sufficient to absorb the entire scattered radiation that strikes the apparatus. 
   An alternative possibility is that the lead used for absorption is accommodated in a transparent material, in particular glass, so that the radiation absorption apparatus is totally transparent. Lead glass can thus also be used to construct the absorption apparatus, which gives the doctor the opportunity to observe the region screened by this. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other advantages, characteristics and details of the invention emerge from the exemplary embodiments described in the following and on the basis of the drawing. This shows: 
       FIG. 1  a schematic sketch of an inventive radiation image capture apparatus of a first embodiment, 
       FIG. 2  a perspective view of a radiation absorption apparatus, 
       FIG. 3  a perspective representation of a wall of the radiation absorption apparatus from  FIG. 2 , in a first embodiment, 
       FIGS. 4 and 5  a wall version of a radiation absorption apparatus of a second embodiment, 
       FIGS. 6 and 7  a wall embodiment of a scattered radiation absorption apparatus of a third embodiment, and 
       FIG. 8  a schematic representative of a radiation image capture apparatus of a second embodiment. 
   

   DETAILED DESCRIPTION OF INVENTION 
     FIG. 1  shows an inventive radiation image capture apparatus  1 , comprising a radiation source  2 , for example an x-ray source, which emits x-ray radiation  3  in the shape of a cone, which is filtered via a filter  4 . The x -ray radiation strikes an examination object  5 , passes through this and is received by a radiation image receptor  6  and converted into corresponding image signals which are read out and processed via an image processing apparatus  8  and output on a monitor  9 . The operation of the x-ray source  2  and of the image processing apparatus  8  is controlled via a central control apparatus  10 . 
   At the radiation image receptor  6 , which is designed here for example as a solid-state radiation detector, a radiation absorption apparatus  11  is provided which is arranged at the radiation image receptor  6  so as to be moveable via suitable linear guides. The embodiment shown is a rigid radiation absorption apparatus which can be moved in its entirety in the linear guides in respect of the radiation receptor  6 , as represented by the double arrow  7 . Using the radiation absorption apparatus  11 , which is closed on all sides, the distance between the radiation image receptor  6  and the examination object  5  can be spanned and laterally closed. The result of this is that scattered radiation  12 , which otherwise would not strike the radiation image receptor  6 , strikes the radiation absorption apparatus  11  and is absorbed thereby, and consequently cannot enter the environment, while the primary radiation  13  can strike the radiation image receptor  6  unimpeded. 
   It should be noted here that in  FIG. 1  only the two sides of the radiation absorption apparatus  11  are represented; naturally in the case of a rectangular embodiment the absorption apparatus has four side walls which form a laterally closed cube. 
   The front edges of the top and bottom side walls can be slightly curved corresponding to the shape of the patient, in order to be brought as close as possible to the patient. 
   Additionally in  FIG. 1  the possibility is al so represented (by a dashed line) of also providing a radiation absorption apparatus  14  at the radiation source  2 , said radiation absorption apparatus  14  expanding out in the shape of a cone or truncated pyramid toward the examination object  5  in the example shown. It equally serves to absorb scattered radiation  15 , which of course can also be scattered toward the radiation source  2 . This radiation absorption apparatus  14  too is closed on all sides. If both radiation absorption apparatuses  11 ,  14  are provided, the complete beam path from the radiation source  2  to the radiation image receptor  6  is enclosed, so that maximum absorption of scattered radiation is achieved. 
     FIG. 2  shows a schematic representation of the radiation absorption apparatus  11  from  FIG. 1 . It can be seen to have a total of four side walls  16   a ,  16   b ,  16   c  and  16   d  which form a box which is closed on all sides. Also shown is the radiation image receptor  6 , which in this case is rectangular or square, for example the solid-state radiation detector, on which the rigid radiation absorption apparatus  11  can be relocated linearly. 
     FIG. 3  shows a section through a wall of a radiation absorption apparatus, as shown in  FIG. 2 , the wall itself being rigid. An absorption element  17  is shown, for example a band-shaped lead element which is accommodated in a sheath  18 , for example a plastic jacket. 
     FIGS. 4 and 5  show an alternative wall structure. Here three separate sections  19   a ,  19   b  and  19   c  made of radiation-absorbent material, for example lead, are provided, which are accommodated in a common sheath  20 . The sections  19   a, b, c  are connected to one another (in a manner not shown in greater detail) so as to move together. They can be relocated between the extended position in  FIG. 4 , in which they are arranged virtually behind one another and offset to one another, and the retracted position in  FIG. 5 , in which they lie essentially parallel next to one another. The movement linkage can be such that, for example, initially on extension from the closed position in  FIG. 5  the section  19   a  is drawn out of the unit. If it has reached a particular position and if it is moved further, it automatically takes the next section  19   b  with it, until this has been moved into the end position, in which then the sections are furthest extended. 
     FIGS. 6 and 7  show another wall embodiment. Here too three absorption sections  21   a ,  21   b  and  21   c  are provided, which are accommodated in a sheath  22 , and which here are linked to one another in the manner of an accordion, so that, as  FIG. 7  shows, they collapse or fold up virtually in the manner of an accordion. None of the sections is represented to scale. In reality they have e.g. a thickness of 1 mm and a height or length of e.g. 10 cm. 
   A radiation absorption apparatus can in principle be relocated or generally moved manually. Alternatively, however, it is also conceivable for the movement to be motor-driven, i.e. automatic, such an embodiment being shown in  FIG. 8 . In the inventive radiation image capture apparatus  23  described there, in which only a radiation absorption apparatus  25  provided at the radiation receptor  24  is provided, a motor  26 , which for example can likewise be controlled via the central control apparatus  10 , is provided, by means of which the radiation absorption apparatus  25 , which for example is rigid in accordance with the embodiment according to  FIG. 2 , can be relocated automatically in respect of the radiation receptor  24 . The means the positioning relative to the examination object  27  takes place automatically. To avoid the radiation absorption apparatus  25  striking the examination object  27  and to detect the optimum positioning in respect of the examination object  27 , in the example shown a sensor  28  is provided, which communicates with the control apparatus  10 , the control apparatus  10  controlling the motor  26  as a function of the sensor detection. It is expedient in the case of a rectangular box embodiment of the radiation absorption apparatus for example to position such a sensor  28  on each side wall. 
   In the embodiment according to  FIG. 8  the radiation source  29  and the radiation receptor  24  are arranged on a C-arm  30 . This is movable in known manner, as is indicated by the double arrow. To avoid the radiation absorption apparatus  25 , which is optimally positioned for a preceding image capture, striking the examination object  27  when such a rotational movement is initiated, the control apparatus  10  is advantageously designed so that the motor  26  can be controlled for a short, quick backward movement of the radiation absorption apparatus  25  from the former capture position, so that there is sufficient clearance between front edge of the radiation absorption apparatus  25  and the examination object  27 . The C-arm  30  can now be moved without danger. In the new position the control apparatus  10 , controlled via the one or more sensors  28 , can then extend and optimally position the radiation absorption apparatus  25  again via the motor  26 .