Patent Publication Number: US-2017347976-A1

Title: X-ray mammography and/or breast tomosynthesis using a compression paddle with an inflatable jacket enhancing imaging and improving patient comfort

Description:
FIELD 
     This patent specification pertains to mammography and/or breast tomosynthesis using an inflatable compression paddle jacket that improves patient comfort and imaging results. 
     BACKGROUND AND SUMMARY OF THE DISCLOSURE 
     A significant patient concern in mammography and breast tomosynthesis is the discomfort the patient may feel when the breast is compressed, typically between two rigid plastic surfaces, with sufficient force to immobilize the breast and spread out the breast tissues for x-ray imaging. Another significant challenge is to ensure that the imaged field include the desired amount of breast tissue. The reasons for using compression include: (1) to make the breast thinner in the direction of x-ray flux and thereby reduce patient radiation exposure from the level required to image the thicker parts of a breast that is not compressed; (2) to make the breast more uniform in thickness in the direction of x-ray flux and thereby facilitate more uniform exposure at the image plane over the entire breast image; (3) to immobilize the breast during the x-ray exposure and thereby reduce image blurring; and (4) to bring breast tissues out from the chest wall into the imaging exposure field and thus image more tissue. As the breast is being compressed, typically a technician manipulates the breast to position it appropriately and counter the tendency that compression has of pushing breast tissue toward the chest wall and out of the image field. 
     Standard compression methods for mammography and tomosyntesis use a movable, rigid clear plastic compression paddle. The breast is placed on a breast platform that typically is flat, and the paddle is then compressed onto the breast, usually while a technician or other health professional is holding the breast in place and perhaps manipulates the breast to ensure proper tissue coverage in the image receptor&#39;s field of view and to help spread the breast. 
     One reason for discomfort that the patient may feel is that the compression force is non-uniformly distributed throughout the breast. It is concentrated at the thickest portion of the breast, usually near the chest wall, at or near the lower front edge of the compression paddle and the upper front corner of the breast platform. The anterior portion of the breast, such as near the nipple, may receive less compressive force, or no compression force. The paddle may not even contact this portion of the breast. (The terms front, lower and upper pertain to using a CC imaging orientation, with the patient facing the front of the imaging system, although it should be understood that other imaging orientations, including MLO, are used with the same equipment and these terms need to be adjusted accordingly.) 
     Some systems improve patient comfort by providing compression paddles that tilt as the breast is being compressed. A tilting paddle arrangement is available in various paddle sizes from Lorad of Danbury, Conn., a division of the assignee hereof, Hologic, Inc. of Bedford, Mass., under the trade name F.A.S.T. (of FAST). This tilting paddle provides more uniform compression across the breast, and more comfortable breast examinations. 
     Other methods for improving patient comfort have been proposed and some have been in clinical use to improve patient comfort. One is the use of relatively thin foam pads that are placed above and/or below the breast. The pad deforms to some extent during the compression procedure and may provide improved comfort by spreading out the pressure to a greater extent than using a hard-surfaced paddle and/or breast platform alone. One such pad system is discussed in commonly owned U.S. Pat. Nos. 6,968,033, 6,765,984, 6,577,702, and 7,505,555, and published U.S. patent application US 2003/0007597 A1. Another pad system is proposed in U.S. Patent Nos. 6,850,590 and 6,975,701 and published U.S. patent applications US 2006/0050844 A1, US 2004.0156472 A1 and US 2003/0099325 A1, all naming as the inventor Benjamin M. Galkin Such pads are not transparent to visible light. As a result, if such a pad is between the breast and the compression paddle, the breast will not be visible through the paddle, and this can impair the technician&#39;s effort to position and manipulate the breast during compression. The pad needs to be made of fairly dense thin form, so as to provide meaningful deformability when compressed under or above the breast. If the foam pad slips during positioning and as a result does not cover the entire imaging field, an edge of the pad may cause image artifacts. 
     Another system for improving patient comfort has been proposed for a different purpose—to immobilize the breast during biopsy—by Scientific Biopsy (www.sbiopsy.com). It is understood to use a soft, trough-shaped support to cradle the breast and a flexible band that wraps over the breast to impose a holding force. A thin plastic sheet compressing a breast for ultrasound examination rather than for x-ray imaging is proposed in published patent application US 2003/0007598 A1 (see, e.g.,  FIG. 7  and paragraph [0115]) but no teaching could be found that the material is transparent to visible light or that the arrangement is useful for x-ray imaging or with a flat breast platform. U.S. Pat. No. 6,682,484 discusses the use of a polymeric membrane stretched under tension to restrain the breast during sonographic and/or x-ray imaging. U.S. Pat. No. 7,822,457 discusses the use of tensioned membrane to compress the breast for medical imaging, and that the membrane may be tensioned with a mechanical device or by means of an inflatable bladder. U.S. Pat. No. 6,587,578 discusses a non-rigid object holder comprising a resilient membrane attached to a first member to form an inflatable component for holding the object to be examined between the inflatable component and a base support. 
     Commonly assigned U.S. Pat. Nos. 7,489,761 and 7,792,244 describe (1) placing a fluid-filled pillow or bag between the compression paddle and the breast before the breast is compressed, (2) compressing the breast with a sheet of a material such as Mylar stretched or at least supported between two rods or rollers (instead of using a conventional compression paddle), and (3) using a paddle provided with a lining of concave compressible material. 
     All of the patents and applications identified above are hereby incorporated by reference in this patent specification as though they are fully set forth herein. 
     While at least some of the systems mentioned above are believed to have advantageous features, it is believed that a need still remains to further improve breast imaging and patient comfort. This patent specification is directed to new approaches to address challenges in breast imaging and particularly x-ray breast imaging. 
     One non-limiting example of such new approaches in mammography and/or breast tomosynthesis involves the use of a specially adapted device to control, distribute and re-direct breast compression forces. Preferably, the device comprises an inflatable jacket for the compression paddle. 
     In a non-limiting example, an x-ray breast imaging system that uses the new approach comprises a data acquisition unit in which an x-ray source selectively emits an imaging x-ray beam, an image receptor receives the beam and produces x-ray imaging information in response thereto, and a breast immobilizer that is between the source and the receptor. The immobilizer comprises a breast platform configured to support a patient&#39;s breast for imaging with said beam and a compression paddle supported for movement toward the breast platform to compress the breast and away from the breast platform to release the breast. The compression paddle has a front wall configured to be adjacent the patient&#39;s chest wall when the patient&#39;s breast is supported for imaging, side walls extending transversely to the front wall, and an underside facing the breast platform. A paddle jacket is removably secured to the compression paddle. Typically, the jacket has a double thickness bottom that extends along the underside of the paddle when secured to the paddle and forms an inflatable chamber. A fluid conduit extends from the chamber to a device to inflate the chamber. Typically, there is a quick-attach coupling between the conduit and the chamber, so that the chamber can be in fluid-flow communication with a fluid control unit that selectively supples fluid to the chamber to selectively inflate the chamber. An image processor coupled with the image receptor is configured to receive imaging information and produce x-ray images. A workstation and system control unit is configured to control system operations thereof in response to operator inputs. 
     The compression paddle jacket typically has front and side walls extending along the front and side walls of the compression paddle, respectively, and can be releasably secured to the compression paddle in any one of a number of different ways. In one example, one or more of the jacket&#39;s front and side walls comprise clipping members configured to releasably clip upper portions of one or more of the front and side walls of the compression paddle. In another example, the jacket&#39;s bottom and, if desired, the front and side walls as well, adhesively adhere to the compression paddle. An exterior portion of one or more of the front wall and bottom of said jacket can include a friction-enhancing surface configured to enhance friction with the patient&#39;s skin. The friction enhancing surface can comprise a surface with a sticky substance therein or thereon. 
     The jacket bottom preferably is substantially transparent to visible light, whereby a technician adjusting a patient&#39;s breast for imaging can visualize the breast through said jacket. A non-limiting example of jacket material is vinyl. The jacket bottom can include markings of a material that attenuates the x-ray beam sufficiently to make the markings visible or at least detectable in said x-ray images. The jacket&#39;s inflatable chamber in divided into two or more sub-chambers that are inflatable to different pressures. In one example, the jacket can be made of two layers of flexible sheet material that are seamed at least at a portion that extends along a junction between the front wall and the underside of the compression paddle. 
     In one example of breast imaging, a technician secures the inflatable jacket to the compression paddle and makes a connection between the jacket chamber and a fluid conduit. With the patient&#39;s breast on the breast platform, the technician lowers the paddle to compress the breast while manipulating breast tissue, and inflates the jacket&#39;s chamber to a pressure that achieves a desired compression and spreading of breast tissue. The immobilized breast is imaged in the desired imaging mode. Typically, a new paddle jacket is used for each patient, so the technician disconnects the fluid flow connection and disposes of the used jacket. The inflation and deflation can be operator-powered, such as by a hand or foot operated pump, with appropriate operator-controlled valves, or powered under operator control using suitable electric or other pumps controlled by buttons or other interface devices or under computer control triggered by the operator or by positioning the paddle relative to the breast (e.g., inflating when the paddle has reached a certain position or acts on the breast with w certain force). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partly schematic view and partly a block diagram of a mammography and/or tomosynthesis system using an inflatable or inflated paddle jacket in imaging a patient&#39;s breast with x-rays. 
         FIG. 2  is a partial perspective view, not to scale, which illustrates a compression paddle provided with an inflatable or inflated jacket and a breast platform with a compressible mat thereon, as a part of an x-ray mammography and/or tomosynthesis system. 
         FIG. 3  illustrates schematically a section of the compression paddle with a paddle jacket secured thereto. 
         FIG. 4  illustrates schematically two examples of ways to releasably secure a paddle jacket to a compression paddle. 
         FIG. 5  illustrates schematically a seam in the paddle jacket. 
         FIG. 6  illustrates a variant in which the bottom of the jacket comprises multiple chambers that can be pressurized to different degrees. 
         FIG. 7  is a perspective view of an inflatable jacket secured to a compression paddle (upside down). 
         FIG. 8  illustrates a compression paddle with an inflatable jacket secured thereto, and with the combination secured to a breast imaging system. 
         FIG. 9  illustrates a breast imaging system using an inflatable jacket over the compression paddle. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , a patient&#39;s breast  10  is immobilized for x-ray imaging between a breast platform  12  and a compression paddle  16 . Platform  12  can be the upper surface of a housing  14 . At least an underside of compression paddle  16  is covered with an inflatable paddle jacket  18 . Platform  12  and paddle  16  form a breast immobilizer unit  20  that is in a path of an imaging beam  22  emanating from x-ray source  24 . Beam  22  impinges on image receptor  26  that is in housing  14 . Immobilizer  20  and housing  14  are supported on an arm  28 . X-ray source  24  is supported on an arm  30 . For mammography, support arms  28  and  30  can rotate as a unit about an axis such as at  30   a  between different imaging orientations such as CC and MLO, so that the system can take a mammogram projection image Mp at each orientation. Image receptor  26  remains in place relative to housing  14  while an image Mp is taken. Immobilizer  20  releases breast  10  for movement of arms  28  and  30  to a different imaging orientation. For tomosynthesis, support arm  28  stays in place, with breast  10  immobilized and remaining in place, while at least source support arm  30  rotates source  24  relative to immobilizer  20  and breast  10  about an axis such as  30   a . The system takes plural tomosynthesis projection images of breast  10  at respective angles of beam  22  relative to breast  10 . Concurrently, image receptor  26  may be tilted relative to breast platform  12  in sync with the rotation of source support arm  30 . The tilting can be through the same angle as the rotation of course  24 , but preferably is through a different angle, selected such that beam  22  remains substantially in the same position on image receptor  26  for each of the plural images Tp. The tilting can be about an axis  32   a , which can but need not be in the image plane of image receptor  26 . A tilting mechanism  34 , which also is in housing  14  or is otherwise coupled with receptor  24 , can drive image receptor  24  in a tilting motion. Axes  20   a ,  24   a  and  26   a  extend left-right as seen in  FIG. 1 , and may but preferably do not coincide. For tomosynthesis imaging, breast platform  12  can be horizontal or can be at an angle to the horizontal, e.g., at an orientation similar to that for conventional MLO imaging in mammography. The system of  FIG. 1  can be solely a mammography system, or solely a tomosynthesis system, or a “combo” system that can perform both mammography and tomosynthesis imaging. An example of such a combo system is been offered by the assignee hereof under the trade name Selenia Dimensions. 
     When the system is operated, image receptor  26  produces imaging information in response to illumination by imaging beam  22 , and supplies it to image processor  34  for processing to generate breast x-ray images. A fluid control unit  36  connects with inflatable jacket  18  via conduit  36   a , preferably through a quick-release snap-on connection  48 . A system control and work station unit  38  controls the operation of the system and interacts with a user to receive commands and deliver information including processed-ray images. 
     Referring to  FIGS. 1-6  (which are not to scale) for a more detailed illustration of breast immobilizer  20 , compression paddle  16  typically is made of clear plastic and has a front wall  16   a , a left side wall  16   b , a right side wall  16   c , and a bottom wall  16   d  having an underside  16   e . Side walls  16   b  and  16   c  are supported by a bracket  16   f  that in turn is supported by support arm  28  for up-down movement along arm  28 . For tilting relative to breast  10 , paddle  16  is secured to bracket  16  with pins  16   g  (only the right pin is visible in  FIG. 2 ) and is spring biased such that as paddle  16  presses against breast  10  the front end of paddle  16  lifts against the biasing force. If desirable, a compressible pad  40  may be placed on platform  12  to increase patient comfort, as in known for system offered by the common assignee. In addition, compression paddle  16  can move left-right as in the current system offered by the assignee under the trade name Selenia Dimensions. 
     An inflatable jacket  18  is releasably secured to compression paddle  16  and has a front wall  18   a , a left side wall  18   b , a right side wall  18   c , and a bottom  18   d  having a top wall  18   e  facing the underside  16   e  of platform  16  and a bottom wall  18   f . Bottom  18   d  thus comprises an inflatable chamber formed between walls  18   e  and  18   f  of jacket  18 . This chamber  18   d  is in fluid flow communication with fluid control unit  36  via conduit  36   a  so it can be selectively inflated and, if desired, selectively deflated, to a desired pressure. A quick connect-release, snap-on connector  48  facilitates convenient connection of chamber  18   d  to fluid control unit  36  and disconnection from unit  36 . If desired the bottom of jacket  18  can be divided into two or more chambers, such as chambers  18   h  and  18   i , by a partition  18   g , and separate conduits and connect/disconnect device (not shown) can be provided for each so that the two or more chambers can be inflated to desired pressures that may differ from each other. 
     Jacket  18  can be releasably secured to paddle  16  in any number of ways such that it can be easily attached and removed from paddle  16  and so that it will not undergo undesirable shifts relative to paddle  16  or the patient&#39;s skin while the breast is being immobilized and imaged. 
       FIG. 3  illustrates one example, in which at least some of the surfaces of jacket  18  that face platform  16  are made of or coated with a material that adheres to platform  16  with a force that is sufficiently high to substantially prevent undesirable movement between platform  16  and jacket  18  but also sufficiently low to allow for easy removal of jacket  18  from paddle  16 . Preferably at least the upper wall  18   e  of jacket  18  is made sticky for that purpose, but any one or more of the other walls can also be made sticky instead of or in addition to wall  16   e . In this example of using adhesion to releasably secure jacket  18  to paddle  16 , the front and side walls of jacket  18  preferably are shorter than the corresponding walls of paddle  16  but in the alternative can be the same height or even taller. The walls of jacket  18  can but need not be the same height; for example front wall  18   a  can have a lesser height compared with side walls  18   b  and  18   c.    
       FIG. 4  illustrates other examples of releasably securing jacket  18  to paddle  16 . In this example, at least one but preferably two or all three of front wall  18   a  and side walls  18   b  and  18   c  are provided with clipping members  42  that clip over the top of the respective wall of platform  16  and thus keep jacket  18  and platform  16  secured to each other. Clipping member  42  can be as shown in solid lines, or it can have an extension  42   a  as shown in dashed line. Jacket  18  typically is made of a plastic material such as vinyl that is somewhat stretchable and is dimensioned for a tight fit over platform  16  such that mechanical friction and perhaps some electrostatic force and inherent stickiness of the jacket material combine to maintain the jacket and platform from undesirable movement with respect to each other, but jacket  18  can still be easily peeled from paddle  16  by an operator so that a new jacket can be installed for the next patient if desired. Other example are contemplated, such as snap connections between the side walls of the jacket and the compression paddle, or other mechanical connections. 
     Jacket  18  can be made of two layers of a material such a vinyl similar in chemical composition and thickness to that used for colostomy bags and even kitchen food bags and freezer bags. Preferably the two layers are fused or adhered to each other at the front and side walls of jacket  18 , but not at the bottom  18   d  of jacket  18 . Preferably, a seam  44  is formed, e.g., with adhesive material or by fusing, joining the two layers where jacket  18  adjoins the junction of the front and underside of platform  16  when jacket  18  is secured to platform  16 , as illustrated in  FIG. 5 . Seam  42  can extend partly over front wall  16   a  and partly over underside  16   e  of platform  16 , as illustrated (not to scale) in  FIG. 5 . Preferably, seam  42  is positioned such that the inflatable volume  18   d  of jacket  18  does not extent forward beyond front wall  16   a  of platform  16 , so as not to push patient tissue away from platform  16 . 
     Referring to  FIG. 6 , the jacket&#39;s chamber  18   d  can comprise two or more sub-chambers, such as shown at  18   h  and  18   i , each with a respective connection through a snap-on connector and a conduit to fluid control unit  36 , so that each sub-chamber can be inflated to a desired pressure level under operator control or automated system control. 
     Fluid control unit  36  can be powered by an operator, using a hand-pump or a foot pump and appropriate manual or foot-controlled valves. Alternatively, electric or fluid-powered pumps can be used, with appropriate valves and interfaces such as buttons or switches that the operator controls. As another alternative, fluid control unit  36  can be fully automated such that inflation/deflation of jacket  18  is under control of station  38 , when so enabled by an operator, and in response to events such as compression paddle  16  reaching a certain position relative to the patient&#39;s breast or to platform  12  or exerting a specified pressure on the patient&#39;s breast. The controls over inflation/deflation can be a part of or at least associated with unit  38 . 
     In use, the mammography and/or tomosynthesis system is operated as known, for example as known for the systems offered by the common assignee under the commercial designations Selenia and Selenia Dimensions, except for the addition of inflatable paddle jacket  18 . Thus, before patient imaging, a jacket  18  is secured to paddle  16  and connected to conduit  36  through a snap-on connector  48 . With patient&#39;s breast  10  on platform  12  or pad  40 , the technician lowers paddle  16  (with jacket  18  secured thereto) to begin compressing breast  10 , while manually manipulating the breast to spread out breast tissue and pull tissue away from the patient&#39;s chest wall and into the x-ray field of view. In this process, the technician may control the degree of inflation of the jacket&#39;s chamber  18   d  before and/or after paddle  16  has been lowered to its final desired position by adding to and/or releasing fluid from chamber  18   d . If chamber  18   d  comprises two or more sub-chambers, the technician may individually control the inflation of each in a similar manner. Once the technician or other health professional is satisfied with the position of breast  10 , x-ray imaging can commence in a mammography and/or tomosynthesis mode, for example as known for said systems offered by the common assignee. 
       FIGS. 7-10  illustrate examples of an inflatable or inflated jacket  18  secured to a compression paddle in a breast imaging system. In  FIG. 7 , jacket  18  and paddle  16  are upside-down to better illustrate them and quick-release coupling  48 .  FIG. 8  illustrates paddle  16  and jacket  18  in a more typical orientation, and also illustrates a knob  80  that can be manually turned to move paddle  16  and its support left-right.  FIG. 9  illustrates in perspective view a system in which components are identified by reference numeral used in  FIG. 1  and described in connection with  FIG. 1 . 
     While specific examples have been described above, it should be clear that variations thereof are within the scope of the invention defined by the appended claim. As one of many possible examples, a similar inflatable jacket can be used on or over breast platform  12  in addition to or instead of using jacket  18  on compression paddle  16 . In that example, such a jacket can be similarly secured to housing  14 , or it can omit the side walls so that only a chamber similar to chamber  18   d  (or multiple sub-chambers) is present on breast platform  12 , possibly with a front wall similar to front wall  18   a  but extending down along the front wall of housing  14