Abstract:
The detection of a compression pad in a mammography apparatus is automated. A rear face of the pad is provided with identifying and positioning readable by the sensors of a mobile carriage of the mammography apparatus. The reading is converted into a binary word that enables the mammography apparatus to obtain the operating parameters and to automatically associate reading keys with an image. A reading key is, for example, the name of the examination/image associated with the pad.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of a priority under 35 USC 119(a)–(d) to French Patent Application No. 0211948 filed Sep. 26, 2002, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     The present invention is directed to a radiological apparatus for imaging of an object, and in particular, to a mammography apparatus with detection of compression pad, i.e., a mammography apparatus in which an operator positions the compression pad on its support, and the mammography apparatus will automatically set the parameters for the pad. 
     A radiological imaging apparatus, such as a mammography apparatus, is an apparatus used to take images of a patient&#39;s breast by means of radiation. In practice the apparatus comprises a vertical column bearing a breast-support tray on which the patient breast is placed so that an image can be taken. Beneath the breast-support tray, there is a means for detection, usually a cartridge with a photosensitive film or a digital means, as well as various devices to limit undesirable effects in the image. The top of the column bears means for providing a source of radiation, such as an X-ray tube, whose ray of radiation are directed toward the means for detection. 
     The acquisition of the mammography image, designed in particular to reveal the presence of microcalcification, which may be evidence of incipient cancer, might be efficient only under certain conditions. One of the conditions is the hardness of the X-rays. The X-rays must be of a hard type so that the image obtained reveals the structures to be detected with sufficient contrast. Furthermore, for reasons of both stability and image quality, the patient&#39;s breast has to be compressed. Various compressive forces may be applied. These forces are applied through a compression pad that compresses the breast on the breast-support tray, according to the type of image/examination to be made. 
     A given type of pad is therefore related to a type of image/examination. Furthermore, a pad is also described at least by its intrinsic properties, namely its shape, dimensions and the absorption characteristics of the material in which it is made. These characteristics of the pad are important because the stream of X-rays travels through the pad before reaching the breast and then the X-ray sensitive receiver/detector making the measurement/image. It is therefore important to be able to take account of these characteristics for the exploitation, or production, of the images resulting from the examination. 
     In the prior art, the physical characteristics of the compression pad are taken into account either by the operator examining the images or by an algorithm for processing the acquired data and the physician. Whatever the specific situation, the physician must be given reading keys and the algorithm must be provided with processing parameters. These reading keys, or parameters, pertain to the nature of the examination, i.e., they depend on the nature of the view. The views are classified as a function of ranges of angle and position of the image receiver with respect to the breast. Each of these views has a name enabling it to be identified rapidly and simply. For example, there are MLO views (medio-lateral-oblique views of the breast). There also exist Spot views: these are magnified views made with small pads because the observed zone is small. The pads are then called Spot pads. The list of views/examinations is not exhaustive. 
     In the prior art, the operator at a panel connected to the mammography apparatus enters the parameters, or they are viewed on the image through the interposition, between the detector and the radiation source, of an opaque plate comprising a message used to identify the parameters of the image. Manipulations of this kind entail painful waiting periods for the patient while the breast is compressed. Furthermore, the operator is liable to commit information-recording errors that give rise to confusion during the analysis of the images. Indeed, a key assumes all its significance as a function of these interpretation keys. If these keys are poor, it becomes impossible to interpret the picture and therefore to carry out a diagnosis. At worst, this may lead to a wrong diagnosis. The fact that an operator often has to carry out operations to set the parameter of the apparatus increases the possibility of error through the establishment of routine or of lassitude. 
     BRIEF DESCRIPTION OF THE INVENTION 
     An embodiment of the invention is a radiological apparatus, in particular, a mammography apparatus, comprising a column that supports a breast-support tray and a pad for the compression of the breast against the tray, the compression pad being borne by a mobile carriage along the column, wherein the compression pad comprises means for identification of the pad capable of working together with means for reading the mobile carriage, the means for reading working together with a “smart device” of the mammography apparatus for providing an image of a breast, the “smart device” comprising a plurality of tracks and relays. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention and embodiments thereof will be understood more clearly from the following description and from the appended drawings, in which: 
         FIG. 1  is a top view of a compression pad and a mobile carriage; 
         FIG. 2  is a back view of a compression pad; 
         FIG. 3  is a side view of a compression pad and a mobile carriage; 
         FIGS. 4   a ,  4   b  and  4   c  are back views of the compression pad in positions relatives to a mobile carriage and to the reading means of the carriage; and 
         FIG. 5  shows means implemented by the mobile carriage for the reading of the information presented on the compression pad. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a compression pad  101 . In the embodiment, pad  101  has an arm  102  used to move or shift compression block  103  with respect to column  104  of a mammography apparatus (not shown but is well-known in the art). The move or shift is due to constraints related to anatomy and to the space requirement of the mammography apparatus. Pad  101  compresses the breast against a breast-support tray (not shown but is well-known in the art). A breast compressed in this way may then be irradiated optimally, and thus a good image is obtained with minimum radiation. 
     The compression pad  101  is fixed, through the arm  102 , to a mobile carriage  105 . Carriage  105  is mobile in translation along an axis Oz. The mobility of the carriage  105  enables a breast to be compressed between the pad  101  and the breast-support tray. The carriage  105  is fixed, through a sliding link, to column  104 . The motion of the carriage is obtained either through a worm screw, or through a toothed rack or by any other means or equivalents thereof known to one skilled in the art. 
     Carriage  105  has a rail  106  in which a bump  107  of the pad is made to slide, the external dimensions of the bump  107  corresponding to the internal dimensions of the rail  106 . This enables the mobile carriage  105  and the compression pad  101  to be fixedly joined during motions along the axis Oz of the carriage  105 . The introduction of the pad  101  into the carriage  105  is done in a direction Ox perpendicular to the direction Oz. Thus, during compression along the axis Oz, there is no risk that the pad  101  will move along the axis Ox, the compressive force being perpendicular to this axis. However, locking devices, for example, clip-type devices or equivalents thereof, can be used to lock the pad to the carriage once it is in position. Other modes of positioning the pad can be used, for example, modes using hooks. 
     Carriage  105  also has a printed circuit  108 . A surface of the printed circuit  108  is parallel to a rear face of the compression pad  101 . The term “rear face” of the compression pad  101  shall be understood to mean that face of the compression pad  101  that is in contact with the mobile carriage  105 . The rear face of the compression pad fixed to the mobile carriage  105  is before a front face of carriage  105 . The printed circuit  108  comprises at least one reading means  109 , for example a relay  109 , fixed to circuit  108 . Circuit  108  is fixed to the carriage  105  in such a way that the means  109  can read the means of identification of the pad  101 . The circuit  108  should preferably be close to the front face of the carriage  105 . 
       FIG. 2  shows a rear face  201  of the compression pad. The rear face  201  has parallel tracks, or actuators,  202  to  205 . These tracks  202  to  205  are oriented along the axis Ox defined for  FIG. 1 . The nature of the tracks depends on the nature of the means  109 . If the tracks  109  are mechanical relays, then a track is a lengthwise bump of the rear face  201 . By its presence, this bump sets up a contact between the two terminals of the relay. A mechanical track of this kind is, for example, a roller track or a slider track of the cam track type, with at least two levels corresponding to two levels of electrical signals. If it is a magnetic relay, the track is then a magnetized track detectable by magnetic relay. If it is an optical relay, the track is then a thin track made of a reflecting substance. Additional equivalent means can be made or proposed by one skilled in the art. 
     Each track can be seen as an information bit. If the track is present, this means that the bit is at 1. If not, it means that the bit is at 0. The number of relays for the reading of identification information contained in the circuit  108  determines the dynamics of detection by the mammography apparatus. If circuit  108  has three relays for the detection of identification tracks, then the mammography apparatus has a recognition capacity defined by three bits, that is the mammography apparatus is capable of distinguishing  2 ^ 3  rear faces of different compression pads. 
     In the embodiment of  FIG. 2 , rear face  201  potentially comprises four tracks. The presence of a track is detected and corresponds to a value 1, the absence of a track corresponds to non-detection and therefore to a value 0. 
     Thus, with four detectable tracks, namely with four relays for reading position on the circuit  108 , it is possible to detect sixteen different states for a rear face, namely sixteen different compression pads. However, for reasons of robustness of the device, it may be preferred to carry out an encoding as follows: three tracks to encode the type of the pad, and one parity track corresponding to the sum of the first three tracks. It is thus possible to detect worn-out tracks or defective relays, and avert errors of parameterization and/or interpretation. It is possible then, for example, to consider the following table, track  1  being the parity track: 
     
       
         
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Track 1 
                 Track 2 
                 Track 3 
                 Track 4 
                 Interpretation: 
               
               
                   
                   
               
             
             
               
                   
                 0 
                 0 
                 0 
                 0 
                 No pad 
               
               
                   
                 1 
                 0 
                 0 
                 1 
                 Type 1 pad 
               
               
                   
                 1 
                 0 
                 1 
                 0 
                 Type 2 pad 
               
               
                   
                 0 
                 0 
                 1 
                 1 
                 Type 3 pad 
               
               
                   
                 1 
                 1 
                 0 
                 0 
                 Type 4 pad 
               
               
                   
                 0 
                 1 
                 0 
                 1 
                 Type 5 pad 
               
               
                   
                 0 
                 1 
                 1 
                 0 
                 Type 6 pad 
               
               
                   
                 1 
                 1 
                 1 
                 1 
                 Unrecognized pad 
               
               
                   
                   
               
             
          
         
       
     
     The identification tracks  202  to  205  extend along the direction Ox so that they can be detected whatever the position of the compression pad on the mobile carriage. This extension is equal to at least two-thirds of the width of the rear face of the compression pad. Tracks  202  to  205  are centered, along the axis Ox, on an axis parallel to the axis Oz and divide the rear face of the pad into two equal parts. 
       FIG. 3  shows a side view of a device.  FIG. 3  shows the mobile carriage on the column  104  along the axis Oz. Column  104  is itself fixed to an arm  301  fixedly joined to the rest of the mammography apparatus (not shown). The arm can pivot about an axis Oy perpendicular to the axes Ox and Oz defined above. The tilt of the arm  301  with respect to a given direction, vertical or horizontal, is accessible to the mammography apparatus. Knowledge of this tilt makes it possible to refine the information obtained by reading of the rear face of the pad during the parameterization of the mammography apparatus or during the production of interpretation keys for an image. 
       FIG. 3  also shows circuit  108  located in front of the rear face of compression pad  101  fixed to mobile carriage  105 . Circuit  108  has four relays  302  to  305  respectively, located so as to be facing tracks  202  to  205 , respectively. Tracks  302  to  305  are preferably aligned in parallel to the axis Oz.  FIG. 3  show that the carriage  105  has grooves  106  and  306  on the upper part of its front face, and on the lower part of its front face. An upper bump  107  and a lower bump  307  of the pad  101  slide in the grooves. The sliding is done in a direction parallel to the axis Ox. The sliding of the compression pad slide on the mobile carriage makes it possible to position the pad in the appropriate position according to the type of image to be made. 
       FIGS. 4   a ,  4   b  and  4   c  illustrate the manner for automatically detecting the position of the compression pad on the mobile carriage. A rear face  401  has three tracks  402  to  404  for the identification of the compression pad. The rear face  401  also has a localization track  405  parallel to the identification tracks. To co-operate with the tracks  402  to  404  a carriage has relays  406  to  408  positioned before tracks  402  to  404  once the pad comprising these tracks is positioned on the carriage. The relays  406  to  408 , like the relays  302  to  305 , are aligned in a direction parallel to the axis Oz.  FIGS. 4   a ,  4   b ,  4   c  also illustrate that for one of the identification tracks, in this case the track  404 , not to be active. This is means that the track  404  is not present on the rear face of the compression pad, or that the track  404  does not switch over the relay  408 . 
       FIGS. 4   a ,  4   b ,  4   c  show a mobile carriage having several relays associated with a positioning/localizing track.  FIGS. 4   a ,  4   b , and  4   c  show, for example, two relays  409  and  410  that can be actuated by the positioning track  405 . Track  405  is an actuator for the relays  409  and  410 . A positioning track therefore extends preferably in a direction parallel to axis Ox. The positioning detection relays are placed on the route of track  405  when the compression pad is shifted on the mobile carriage. 
     Thus,  FIG. 4   a  illustrates a compression pad identified by the active tracks  402  and  403 , and by the inactive track  404  is in a central position. This position is determined by two relays  409  and  410  that are activated by the localization tracks  405 . 
       FIG. 4   b  illustrates a compression pad identified by the active tracks  402  and  403 , and by the inactive track  404  that is in a first lateral position. This position is determined by the relay  409  that is activated by the localization track  405 , and that the relay  410  is inactive. 
       FIG. 4   c  illustrates a compression pad identified by the active tracks  402  and  403 , and by the inactive track  404  that is in a second lateral position. This position is determined by the relay  410  that is activated by the localization track  405 , and that the relay  409  is inactive. 
     In another embodiment, there could be a greater number of relays on the route of track  405 . This would make it possible to refine the knowledge of the position of the pad on the mobile carriage. 
       FIG. 5  provides a schematic illustration of the working of circuit  108 .  FIG. 5  shows a pad  501  that actuates or does not actuate relays  502  to  506 . For this explanation, establish a parallel between  FIG. 4   a  and  FIG. 5  in making the relays  502  to  506 , respectively, correspond to the relays  406  to  410 , respectively. For reasons of longevity and reliability, the relays used are preferably of the LVLE (Low Voltage Limited Energy) type in which the operating voltages are incompatible with the operating voltages of the logic circuits. Relays of this kind are, for example, the REED relays. Each relay  502  to  506 , respectively, is therefore connected to an input of a level-matching circuit  507  to  511 , respectively, that converts the output signals from the relays into signals electrically compatible with control logic. Each output of the matching circuit is furthermore connected to an input of a serializer circuit  512  or parallel-to-serial converter circuit. The serializer circuit  512  also has a connection interface with a bus  513  of the mammography apparatus. Bus  513  is furthermore connected to a microprocessor  514  and to a program memory  515 . Memory  515  comprises at least one zone  515   a  comprising instruction codes by which the microprocessor can interrogate the circuit  512  and thus obtain the state of the relays  502  to  506 . The state of the relays  502  to  506  at a date D provides information on the type (relays  502  to  504 ) of pad fixed to the mobile carriage as well as on the position (relays  505  and  506 ) of the pad. 
     In another embodiment, the serializer circuit  512  is replaced by a memory circuit that can be read in parallel. This replacement enables a faster reading of the state of the relays  502  to  506 . 
     At a date D, each relay is in a given state, open 0, or closed 1. A date D therefore has a corresponding state binary word comprising as many bits as there are reading relays on the pad. In an embodiment, the state binary word then makes it possible to address a memory  516 . Memory  516  is structured as a table. Each line of the table  516  corresponds to a value of the state word. A first column  516   a  of the table  516  correspond to a value of the state word, the second column  516   b  corresponds to parameters associated with this state word. These parameters are parameters corresponding to operations parameterization of the mammography apparatus, parameters for processing measurements made, or parameters used to mark an image so that a practitioner can interpret it. 
     The position of the pad is interesting in the same way as is the type of pad. A pad does not necessarily have a constant section about its direction of shift with respect to the mobile carriage. A pad therefore does not necessarily absorb X-rays in the same way from one position of the pad to another. 
     The embodiments of the invention enables the automatic detection of the type of compression pad used for the image, and the position of the pad on the mobile carriage. This information is useful, firstly, for the automatic annotation of the image when it is being acquired, and secondly for the post-acquisition computations made, after the image has been acquired, by a workstation responsible for presenting the image on a means for display such as a screen. This information is also useful for the production of keys for the interpretation of a picture. Such interpretation keys are, for example, the name of the examination, the type of pad used, a tilt value of an arm of a mammography apparatus, etc. These keys are presented in a device, such as a cartridge, of the image presented to the practitioner, and are produced at the same time as the image is produced by the mammography apparatus. 
     In one pre-acquisition mode, this information can be used to modulate the intensity of the radiation as a function of the quantity of material to be crossed in the pad. This thickness is related both to the type of pad and to its position. 
     In the description, the printed circuit  108  has been placed directly behind the front face of the mobile carriage  105 . In practice, it is possible to use a comb of relays, fixed close to the rear face of the mobile carriage  105  so that the relays of the comb can co-operate with the tracks/actuators of a pad. In this case, the column is connected to the circuit  108  through, for example, a flexible sheet. The circuit  108  can then be positioned anywhere on the mobile carriage  105 . 
     An embodiment of the invention automatically provides the mammography apparatus with information for the exploitation of data acquired during an exposure according to the nature and position of the compression pad. 
     An embodiment of the invention automatically provides to the mammography apparatus information for establishing the parameters for the irradiation as a function of the nature and position of a compression pad. 
     The disclosed invention and embodiments thereof provides a compression pad with means for identification. The means for identification work together with means for reading placed on a mobile carriage that supports the compression pad. The means for identification are passive and therefore need no power supply. The means for identification are accessible, in read mode, whatever the position of the compression pad on the mobile carriage. To supplement the information accessible on the pad, it also comprises means for enabling the mobile carriage to read the position of the pad in relation to the carriage. Knowledge of this position makes it possible to take account of the specific characteristics of shape of the pad during irradiation. 
     The means for reading are, for example one or more relays, which may be mechanical, optical or magnetic. The means for identification and means for positioning are tracks extending in a direction along which the pad is mobile so that it can be positioned for example, with respect to the mobile carriage. Through this extension of the means for reading, the identification of the pad can be made independent of this position with respect to the carriage. 
     One skilled in the art may make or propose various modifications to the structure and/or manner and/or way and/or function and/or means and\or result and equivalents thereof to the disclosed embodiments without departing from the scope and extent of the invention.