Abstract:
A method for imaging a breast is provided. The method includes positioning a breast within a breast holder including a flexible membrane and creating at least a partial vacuum within the flexible membrane. A method of upgrading a mammography system and various configurations of breast holders are also provided.

Description:
[0001]     The invention relates generally to mammography, and more particularly to a breast immobilization device.  
         [0002]     In traditional mammography, compression of the breast may be necessary in order to even out the breast thickness so that all of the tissue can be visualized and to spread out the tissue so that small abnormalities are not obscured by overlying breast tissue. In addition, compression allows the use of a lower X-ray dose since a thinner amount of breast tissue is being imaged, while also holding the breast still in order to eliminate blurring of the image caused by motion. Furthermore, compression reduces X-ray scatter to increase sharpness of picture.  
         [0003]     In 3D imaging of the breast, the need for compression to spread out tissue so that overlying breast tissue does not obscure small abnormalities, is substantially reduced or effectively eliminated. Similarly, dose management can be addressed by changing the X-ray technique. However, breast compression may still be necessary to immobilize breast tissue during examination to reduce patient motion artifacts and to assure good positioning of the breast tissue. However, the force used for compression and for flattening the breast, increases patient discomfort and potentially reduces patient compliance with recommended breast screening intervals.  
         [0004]     Thus, there is a need for a system and method for breast imaging that is comfortable for the patient, allows maximum coverage of the breast tissue during examination, and facilitates immobilization of the breast during examination.  
       SUMMARY  
       [0005]     In accordance with one aspect of the present technique, A method for imaging a breast is provided. The method includes positioning a breast within a breast holder including a flexible membrane and creating at least a partial vacuum within the flexible membrane.  
         [0006]     In accordance with another aspect, a method of upgrading a mammography system is provided. The method includes removing at least one breast support structure in a mammography system and positioning a breast holder within the 3D mammography system where the at least one support structure for breast has been removed.  
         [0007]     In accordance with yet another aspect, a breast imaging system is provided. The imaging system includes an imaging source that provides an imaging beam, a breast holder for conforming and immobilizing the breast within the breast holder. The breast holder is coupled to a vacuum pump for generating a partial vacuum between the breast and the breast holder. A detector that detects the imaging beam passing through the breast and a positioning unit for positioning the imaging source and the detecting unit, are also included. The positioning unit aligns the imaging source, the breast holder, and the detector in the same axial line.  
         [0008]     These and other advantages and features will be more readily understood from the following detailed description of preferred embodiments of the invention that is provided in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a diagrammatical view of a breast imaging system in accordance with aspects of the present technique;  
         [0010]      FIG. 2  is a perspective view of the breast imaging system in accordance with aspects of the present technique;  
         [0011]      FIG. 3  is a diagrammatical view of an ultrasound breast imaging system in accordance with aspects of the present technique;  
         [0012]      FIG. 4  is a perspective view of one embodiment of the breast imaging holder in accordance with aspects of the present technique;  
         [0013]      FIG. 5  is a perspective view of an alternative embodiment of the breast imaging holder in accordance with aspects of the present technique;  
         [0014]      FIG. 6  is a perspective view of yet another embodiment of the breast imaging holder in accordance with aspects of the present technique;  
         [0015]      FIG. 7  is a perspective view of an embodiment of the breast imaging holder for use in an ultrasound breast imaging system in accordance with aspects of the present technique;  
         [0016]      FIG. 8  is a perspective view of an embodiment of an elliptical breast imaging holder in accordance with aspects of the present technique; and  
         [0017]      FIG. 9  is a perspective view of another embodiment of a breast imaging holder in accordance with aspects of the present technique. 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0018]     In the subsequent paragraphs, an apparatus for imaging the breast of a subject will be explained in detail. The apparatus described hereinafter provides a means for immobilizing breast tissue during the exam to manage patient motion artifacts and also assures good positioning to enable good coverage of breast tissue. Furthermore, the apparatus reduces the force used for compression and eliminates flattening of the breast, thereby increasing the comfort of the subject and potentially improve compliance of the subject with recommended breast screening intervals. As will be appreciated by those of ordinary skill in the art, the present techniques are applicable to other imaging systems besides X-ray or tomosynthesis, for example ultrasound scanning techniques. Indeed, the exemplary uses and implementations described herein are merely provided as examples to facilitate understanding of the presently contemplated techniques. Therefore, the various aspects of the present technique will be explained, by way of example only, with the aid of figures hereinafter.  
         [0019]     Referring generally to  FIG. 1 , a breast holder will be described by reference to an exemplary breast imaging system designated generally by numeral  10 . It should be appreciated, however, that the breast holder may find application in a range of settings and systems, and that its use in the breast imaging system shown is but one such application. The breast imaging system  10  includes a breast holder  12 , which is coupled to a vacuum pump  14 . The breast holder  12  is a closed enclosure that includes a membrane that can hold the breast of a subject  16  so that there are no motion artifacts arising out of unwanted movement of breast tissue.  
         [0020]     The exemplary breast imaging system  10  also includes an X-ray source  18  and a detector  20 . The X-ray source, or any other imaging beam source known to those of ordinary skill in the art, generates an imaging beam that is detected by the detector  20 . Detector  20  may be coupled to a computing device  22  that analyses the data acquired by the detector and generates an image of the imaged volume, for example, the breast tissue. This generated image may be displayed on a display unit  24 . A position alignment unit  26 , which may be coupled to the computing device  22 , aligns the position of the X-ray source  18  and/or detector  20  for proper imaging of the tissue. Furthermore, the breast holder  12  may be either attached to the position alignment unit  26 , through a rigid or flexible coupling, or placed on a breast support, depending on the application. For example, in tomosynthesis, the breast support may preferably be the surface of the detector  20 , while in computed tomography (CT), it may preferably be a separate device, positioned intermediate in position between the X-ray source  18  and the detector  20 .  
         [0021]      FIG. 2  is a perspective view of one embodiment of the exemplary breast imaging system  10  of  FIG. 1 . As previously described, the breast imaging system  10  includes a breast holder  12 . An imaging beam source  18 , such as an X-ray source, may be mounted on a source bearing rail  28 , while a detector  20  may be mounted on a detector bearing rail  30 . The source bearing rail  28  and the detector bearing rail  30  may be utilized to guide the source  18  and detector  20  and align them such that desired imaging of the breast tissue may be achieved. It may be noted that the alignment of source  18  and detector  20 , may be automated or manually controlled. In automated control, motors may drive the beam source  18  and/or the detector  20  along the respective bearing rails  28  and  30 .  
         [0022]     Referring now to  FIG. 3 , a diagrammatical view of an ultrasound breast imaging system  32  is illustrated. The ultrasound breast imaging system  32  includes an ultrasound breast holder  34  that is coupled to a vacuum pump  14 . The ultrasound breast holder  34  includes a membrane, which supports and immobilizes the breast of a subject  16 . The membrane of the ultrasound breast holder  34  includes ultrasound transducers  36  that allow scanning of the breast tissue via ultrasound techniques. A computing device  22  controls the ultrasound signals that is generated and received by the ultrasound transducers  36 . The received ultrasound signals may be analyzed for generating an image of the breast tissue, for determining any lesions, tumors, or other tissue growth in the breast of the subject. The generated image may be displayed on a display unit  24 , which may include a computer monitor, a liquid crystal display (LCD) screen, or the like.  
         [0023]      FIG. 4  is a perspective view of an embodiment of a breast holder  12 . The depicted breast holder  12  includes an outer shell or an outer body  38 , a base plate  40 , and an open end  42 . The outer body  38  of the breast holder  12  may be made of a pliable material, such as plastic, that allows X-ray signals to penetrate into the breast holder. On the rim  44  of the open end  42 , is attached a membrane  46 , which is in a conical shape with the vertex of the conical membrane being coupled to a hole  48 . The membrane  46  may be made of synthetic rubber, or other material that is comfortable for the subject and flexible enough so that the membrane attains the shape of the breast. The membrane  46  may be sealingly coupled to the rim  44  of the open end  42  and the hole  48  such that these two ends are open. At the hole  48 , a vacuum pump  14  may be sealingly coupled so that the volume defined by the membrane  46  may be fully or partially evacuated during operation. Optionally, the base plate  40  of the breast holder  12  may be provided with a hole  50  for allowing air to escape as the breast holder  12  is partially filled with tissue when vacuum pressure is applied inside the membrane  46 . A sealing liquid or cream may be applied to the patient contact surface on the chest wall to improve sealing and ability of the vacuum to draw the tissue into the breast holder  12 .  
         [0024]     In operation, the breast of a subject is positioned inside the membrane  46  from the open end  42 , so that the membrane assumes the shape of the breast. Air present within the membrane  46  may be evacuated to a partial vacuum pressure. Under partial vacuum, the breast is drawn into the breast holder  12  and tissue is effectively pulled from near the chest wall into the breast holder. The degree of evacuation may be adjusted to achieve appropriate compromise between comfort of the subject and tissue drawn into the breast holder  12 . Because the breast tissue is drawn into the breast holder  12 , good coverage of the tissue is achieved.  
         [0025]     Turning now to  FIG. 5 , an alternative embodiment of the breast holder  52 , without a membrane is illustrated. In operation, the breast holder  52  may be filled with a fluid medium that fills the space between the breast and the outer body  38 . Hole  50  may be used to fill the breast holder  52  with the fluid medium, after positioning the breast. Alternatively, the breast holder  52  may be pre-filled with the fluid medium, and the fluid may be drawn out of the hole  50 .  
         [0026]     Another alternative embodiment of the breast holder is illustrated in  FIG. 6 . In this embodiment, the breast holder  54  has a rim  44  on which is attached the membrane  46 . However, this breast holder  54  does not have an outer body. Instead, the breast holder  54  includes one or more support structures  56  that provide mechanical support to the rim  44 . The membrane  46  may be coupled to the rim  44  and a hole  48  provided on the base plate  40 . This breast holder  54  may be used similarly as the other configurations discussed above.  
         [0027]      FIG. 7  is a perspective view of an embodiment of the breast holder for use in the ultrasound breast imaging system of  FIG. 3 . The breast holder  34  is similar to the breast holder  12 , shown in  FIG. 4 . However, in this embodiment, the membrane  46  includes ultrasound transducers  36  that may be embedded on the membrane  46 . In other embodiments, the ultrasonic transducers  36  may be positioned on the outer shell  38 , while the space between the outer shell and the membrane  46  is filled with a liquid (e.g. water) to allow the ultrasound to propagate into the breast. The ultrasound transducers  36  may transmit and receive acoustic signals for an ultrasound scan of the breast. As noted above, during an ultrasound scan, the membrane  36  and/or the space between the membrane and the outer body  38  may be filled with a fluid medium, such as water for facilitating the scan by allowing acoustic waves to penetrate easily.  
         [0028]     Various other configurations of the breast holder may be designed, depending on patient characteristics, system requirements, among other parameters. Breast holders of various sizes (e.g., diameter, holder body height) may be provided to allow for patient specific anatomical differences. Although, the described embodiments have a cylindrical shape and circular cross-section, other embodiments may have an elliptical configuration or a hexagonal configuration or more complex shapes. Elliptical cross-sections, as illustrated in  FIG. 8 , and sections with a secondary aperture to allow better inclusion of tissue near the pectoral muscle, as illustrated in  FIG. 9  may be constructed. In the elliptical configuration  58 , the base plate  40  and the rim  44  may be designed in an elliptical shape. Similarly, in the configuration  60  of  FIG. 9 , the base plate  40  and the rim  44  may be designed such that a sectional plane for the same would have a narrow end  62  and a broad end  64 , as illustrated. The narrow end  62  allows inclusion of the pectoral muscle of the subject for providing better scanning coverage.  
         [0029]     In all the configurations discussed above, outer body  38  may be made of a plastic or other rigid material that transmits X-rays. Alternatively, a more pliable material that can more easily conform to the shape of the anatomy may be utilized. The membrane  46  may be made of a soft, pliable material, such as a synthetic rubber compound or other material approved by Food and Drug Administration (FDA). Custom fabrications, where the patient is fitted a few hours or days before the breast examination, may also be implemented.  
         [0030]     Although the embodiments illustrated and described hereinabove represent only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. For example, an existing breast support structure (such as, a breast compression paddle) in a breast X-ray imaging system, a breast CT scanning system, a tomosynthesis application, or a breast ultrasound imaging system, may be replaced with the breast holder that is disclosed hereinabove. Furthermore, breast holders described above may be employed in the applications noted above as will be appreciated by those of ordinary skill in the art. Similarly, the breast holder may have other cross-sections, such as a hexagonal configuration.  
         [0031]     Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.