Abstract:
A medical imaging device is provided. The medical imagining device includes an object support; a handle; a radiation source configured to emit radiation from a plurality of positions about the object support, wherein the positions are located substantially in a plane; a radiation detector configured to detect the radiation emitted by the radiation source; and displacement means configured to shift the handle relative to the radiation detector and to the radiation source.

Description:
FIELD OF INVENTION 
     The field of the invention relates generally to medical imaging, and more particularly to a medical imaging device for mammography. 
     BACKGROUND OF THE INVENTION 
     Tomosynthesis is a variant of conventional planar tomography in which a limited number of radiographic projections of an organ of a patient is acquired in digital form at different angles relative to the patient. The set of projections acquired at different angles is then processed to produce 3D information of the organ of the patient. This 3D information can be displayed according to a set of sectional planes or in any other form of 3D representation. 
     Mammography devices via tomosynthesis known to date comprise an arm bearing a radiation source capable of emitting radiation, a radiation detector capable of receiving the radiation, a planar object support placed between the source and the detector, one or more handles located on either side of a plane passing through the source and the detector, a plate placed between the object support and the source for compression of the object to be imaged and the processing means. The arm bearing the source is capable of being moved into a plurality of positions. This arm plays the role of positioner. The source is as such mounted pivoting on the arm to enable orientation of the latter relative to the object support. These devices enable acquisition of radiographic projections of the breast of the patient for different angles during a sequence of exposures to radiation. 
     The dimensions of the devices of the prior art are provided optimal for a patient having criteria morphological means established statistically, for example. 
     However, few patients satisfy these morphological criteria means such that use of such apparatus is a source discomfort for the patient. In fact, leg or arm length (and more generally size) can vary from one patient to another. 
     Embodiments of the present invention provide an ergonomic medical imaging device which is more comfortable for patients. 
     SUMMARY OF THE INVENTION 
     For this purpose, a medical imaging device is provided. The medical imaging device comprises: an object support; a handle intended to be gripped by a patient; a radiation source for emitting radiation from a plurality of positions about the object support, said positions being located substantially in one plane; and a radiation detector capable of detecting the radiation emitted by the source. The device further comprises means adapted for shifting the handle relative to the radiation detector and to the radiation source. 
     Another embodiment of the present invention relates to an imaging method for an imaging device comprising an object support; a handle intended to be gripped by a patient; a radiation source configured to emit radiation from a plurality of positions about the object support; and a radiation detector configured to detect the radiation emitted by the radiation source; wherein the method comprises shifting a handle relative to the radiation detector and to the radiation source. 
     Another embodiment of the present invention relates to a computer program product comprising programmed code instructions for executing the method described hereinabove. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other characteristics and advantages of the device and of the method according to embodiments of the invention will emerge from the following description, which is purely illustrative and non-limiting and must be considered in reference to the attached diagrams, in which: 
         FIG. 1  is a schematic representation of a medical imaging device according to one embodiment of the present invention. 
         FIG. 2  is a schematic representation of a medical imaging device according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  represents a medical imaging assembly  13 . 
     This ensemble  13  comprises a radiation source  14 , a mobile arm  15 , an object support  26 , a radiation detector  17 , control means, processing means  32 , and a pad  74  placed between the object support  26  and the source  14  for compression of an object  16  to be imaged. 
     The mobile arm  15  is capable of being moved about a first axis  19  during a sequence of exposures to radiation. The arm  15  plays the role of positioner. Between each exposure to radiation of the sequence of exposures, the arm  15  is moved to enable acquisition of a radiographic projection of the imaged object  16  for a different angle. The arm  15  bears the radiation source  14  at one of its ends. 
     The radiation source  14  is capable of emitting radiation. The radiation source  14  is for example an X-ray source. The source can be shifted by the arm overall in a plane  60  (hereinafter called “displacement plane of the source”) during an exposure sequence. 
     The object support  26  is capable of receiving the object  16  to be imaged. For example, in the case of mammography, the object  16  is the breast of a patient. The object support  26  is for example a plate. The object support  26  is fixed during a sequence of exposures to radiation. However, the object support  26  can be shifted manually or automatically between two sequences of exposures, especially to adapt the height of the object support as a function of the size of the patient, or for transitioning from one acquisition mode to another. For example, if the user has just completed reconstruction of 3D information in a cranio-caudal view (CC), and wants to obtain 3D information in a medio-lateral oblique view (MLO), the user can control the pivoting of the object support  26  to place it in an oblique plane relative to a vertical plane, the object support and the other elements of the device (i.e. arm mobile, radiation source, radiation detector, etc.) being shifted firmly to shift from CC to MLO. 
     The radiation detector  17  is capable of detecting radiation emitted by the radiation source  14 . The radiation detector  17  is for example a planar sensor or an image amplifier linked to a camera. The radiation detector  17  can be substantially planar or be curved. 
     The radiation detector  17  can be mobile during the sequence of exposures. In this case, the detector  17  is shifted between two exposures to radiation of the sequence of exposures. The radiation detector  17  can also be fixed during a sequence of exposures to radiation. In this case however, the radiation detector  17  can be shifted in translation or shifted in rotation between two sequences of exposures, as can the object support  26 , especially to adapt the height of the detector to the size of the patient or for moving for example from a CC acquisition mode to an MLO acquisition mode. 
     The device also comprises one or more handle(s)  1  intended to be gripped by the patient during a sequence of exposures. Hereinbelow, it is assumed that the imaging device comprises a handle, given for the expert that the device can comprise a plurality of handles. 
     Advantageously, the device comprises displacement means adapted for shifting the handle  1  relative to the radiation detector  17  and to the radiation source  14 . 
     This allows an imaging device according to embodiments of the invention to adapt to the morphology of the patient. In a variant, the displacement means is adapted to vary the depth z of the handle  1  such that it can be moved closer to or moved away from of the patient. 
     This adapts the distance between the handle  1  and the patient as a function of its size. The displacement means can comprise a throat  2  whereof the form is complementary to that of the handle  1  to allow the latter to slide inside the throat  2  between a neutral position and a deployed position. 
     For example in an embodiment illustrated in  FIG. 2 , the handle  1  is a U-shaped tube. The throat  2  also has a U-shape of diameter greater than the diameter of the handle  1  such that it can slide inside the throat  2 . 
     The U-shaped throat  2  is located under the object support  26  such that the object support  26  is positioned between the throat  2  and the radiation source  14 . The throat  2  comprises at least one open end  3  for passage of the handle  1 . This open end is oriented upwards. In other words, the open end  3  of the throat  2  is opposite the radiation source  14 . 
     In the embodiment illustrated in  FIG. 2 , the open end  3  is inclined relative to the vertical in a direction opposite the patient such that the free end  4  of the handle  1  is closer to the patient in the neutral position than in the deployed position. 
     This particular arrangement of the throat  2  adapts the depth of the handle  1  to the size of the patient. The greater the size of the patient, the more the handle  1  deploys such that the free end  4  moves away from the patient to adapt to the length of her arms, while moving upwards. Inversely, the smaller the size of the patient, the more the handle  1  is stowed such that the free end  4  moves closer to the patient to adapt to the length of her arms, while moving downwards. 
     The adjustment in depth of the handle  1  is for example a function of the height y of the object support  26  which depends on the size of the patient. 
     In fact, the length of the arms of a large person is greater than the length of the arms of a small person. 
     When the object support  26  is shifted upwards the handle is shifted towards the rear such that the handle  1  moves away from the patient, for a large patient for example. When the object support  26  is shifted downwards, the handle  1  is shifted forwards such that the handle  1  moves closer to the patient. 
     In another variant, the displacement means is adapted for shifting the handle  1  in a vertical plane parallel to the plane of displacement of the source  14 . 
     This adapts the position of the handle as a function of the acquisition mode—CC or MLO—to be carried out. 
     In the cranio-caudal (CC) acquisition mode, the object support  26  extends in a substantially horizontal plane. The displacement means position the handle  1  to the side of the object support such that it extends perpendicularly to the object support  26 . 
     In the medio-lateral oblique acquisition mode (MLO), the object support  26  extends in an oblique plane relative to a vertical plane. The displacement means position the handle  1  above the object support  26  such that it extends perpendicularly to the object support  26 . 
     This makes the imaging device more comfortable for the patient. In fact, the fact that the handle  1  is always perpendicular to the object support  26  irrespective of the acquisition mode allows the patient gripping the handle to be in a more natural position. 
     Also, the combination of the handle and the displacement means plays the role of positioning means. The handle is shifted to the location where the user wants the patient to put her hand, thus making acquisition easier by limiting the number of explanations necessary for the patient to be positioned correctly during acquisition. 
     Displacement of the handle can be manual. In this case, displacement can be done either by the user, or by the patient herself for adapting the position of the handle to the morphology of the patient and/or to the preferred acquisition mode (CC or MLO). 
     The displacement of the handle can also be automatic. In this case, displacement of the handle is initiated or not by displacement of the object support. 
     In an embodiment, the handle and the object support are connected to independent drive means such as motors. Displacement of the handle is synchronised with displacement of the object support due to a law of displacement executed in software. 
     For example, the object support is shifted upwards or downwards to a use position. The coordinates of the use position are detected using detection means such as an optic sensor. The detection means transmits to processing means—such as a computer—the coordinates of the use position of the object support. 
     The processing means utilizes a conversion table (or “look up table” in English terminology) stored in memory providing the use position of the handle as a function of the position of the object support. The use position of the object support is used at input of the conversion table, which provides at output the use position of the handle. The handle is then shifted by the drive means to its use position. 
     In another embodiment, the handle is connected by mechanical means to the object support such that displacement of the handle is initiated by the object support. Displacement of the object support causes displacement of the handle. 
     In all cases of automatic displacement of the handle, removal means can be provided between the drive means or the mechanical means to allow manual displacement of the handle, especially in the case of a patient presenting a particular morphology (large person having short arms or small person having long arms). 
     The imaging device described hereinabove has numerous advantages, including improving patient comfort. 
     It better adapts the position of the handle as a function of the acquisition mode (CC, MLO) which the user wants and therefore improves ergonomics of the device. This has the advantage if increasing the workspace of the user during the acquisition procedure. 
     It will be evident that numerous modifications can be made without departing in material terms from novel ideas and the advantages described here. 
     For example, displacements of the handle in depth and in the displacement plane of the source can be combined or not. 
     Also, displacement of the handle can be independent of the position of the object support. For example, in an embodiment, the handle is shifted automatically by using a predefined algorithm which establishes a link between a view name and the position of the handle. The view name can be determined for example by using a method described in U.S. Pat. No. 6,687,331. 
     Consequently, all modifications of this type are intended to be incorporated inside the reach of the system and of the imaging method such as defined in the attached claims.