Abstract:
A tissue positioning system for contouring a patient tissue volume includes an axially displaceable interface having a surface configured to engage a breast or other tissue volume. A low pressure source applies a partial low pressure to the surface of the displaceable interface to secure the tissue volume to the surface, and the axially displaceable interface is biased to pull and contour the tissue volume when the tissue volume is secured to the surface. The axially displaceable interface is typically mounted on a telescoping support and the biasing is provided by the same low pressure used to secure the tissue volume.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/293,071 (Attorney Docket No. 50174-733.101), filed Feb. 9, 2016, the full disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates generally to the medical technology field, and more specifically to a new and useful system for positioning and contouring a tissue body in an imaging field. 
         [0004]    Early detection of breast cancer and other types of cancer typically result in a higher survival rate. Despite a widely accepted standard of mammography screenings for breast cancer detection, there are many reasons that cancer is often not detected early. In particular, drawbacks of mammography include: limited performance among women with dense breast tissue, a high rate of “false alarms” that lead to unnecessary biopsies that are collectively expensive and result in emotional duress in patients, and low participation in breast screening, as a result of factors such as fear of radiation and discomfort. In particular, the mammography procedure involves compression of the breast tissue between parallel plates to increase the X-ray image quality by providing a more uniform tissue thickness and stabilizing the tissue. However, this compression is typically uncomfortable, or even painful. 
         [0005]    A relatively new ultrasound imaging technique, referred to as ultrasound tomography, promises to be a practical alternative to mammography without tissue compression and many other drawbacks. With ultrasound tomography, the patient lies on a support surface in a prone position with a breast depending through an opening in the surface into a water bath. A ring or other ultrasonic transducer assembly is then scanned vertically to acquire the image data to be analyzed. Some of the proposed ultrasound tomography systems employ a magnetic or other device to capture the nipple region of the breast to extend and stabilize the breast during imaging. While at least partially effective, such prior breast extending apparatus can be uncomfortable, can deform the breast into a conical shape which is not optimum for imaging, do not provide repeatable shaping of the breast, and cannot accommodate breast of differing sizes. 
         [0006]    For these reasons, it would be desirable to provide systems and methods for performing breast and other ultrasound tomography which provide improved positioning of the breast or other tissue body, improved patient comfort, and which accommodate size variations of the breasts and other tissue bodies among different patients and which allow scans to be performed in a repeatable manner in order to monitor changes in a tissue over time in an individual patient. At least some of these objectives will be met by the inventions described and claimed herein. 
         [0007]    2. Description of the Background Art 
         [0008]    Commonly owned US2014/0276068 and US 2013/0204136 describe an interface system for supporting a patient and exposing a depending breast in an ultrasonic tomography system. U.S. Pat. No. 7,771,360 and U.S. Pat. No. 7,699,783 describe other breast scanning systems having a magnetic capture device for a nipple region of the breast. 
       SUMMARY OF THE INVENTION 
       [0009]    In a first aspect of the present invention, a tissue positioning system for contouring a patient tissue volume, such as a human breast, comprises an axially displaceable interface having a surface configured to engage and attach the tissue volume or a portion thereof. Typically, a low pressure source or appliance is configured to apply low pressure to or over the surface of the displaceable interface. The low pressure secures a target region of tissue volume, such as a nipple region of a breast, to the surface, and the axially displaceable interface is biased to pull, elongate, and/or contour the tissue volume when the tissue volume is secured to the surface. For example, elongating a breast can cause the breast to assume a generally cylindrical shape to enhance subsequent imaging, treatment, interventions, or the like. 
         [0010]    The axially displaceable interface surface is typically formed from a gel, preferably a gel that is engineered to be acoustically/ultrasonically invisible, e.g. by formulating the gel to have a speed of sound equivalent to water at body temperature and to be disposable (single use) both for hygienic reasons. Preferred gels are cross-linking polysaccharide, such as carrageenan (seaweed derived). The gel pads may be fabricated using conventional techniques, such as mixing an aqueous solution, heating the solution, and pouring into a net-shape mold, cooling). 
         [0011]    In a particular embodiment, the tissue positioning system may further comprise a telescoping, accordion or other extendable/retractable support attached to a side of the displaceable interface opposite to the side engaged by the breast or other tissue volume. The extendable/retractable support typically has an interior with a variable volume. In such cases the low pressure force may be connected to apply a low pressure within the interior of the extendable/retractable support in order to bias the displaceable member. Optionally, a coil spring element is disposed within the interior volume of the extendable/retractable support to axially extend the surface of the displaceable interface and apply a spring force against the tissue volume. In such cases, the vacuum applied internally to the extendable/retractable support will be sufficient to pull and elongate the tissue volume against the spring force of the coil spring. 
         [0012]    In other embodiments of the tissue positioning system the coil spring element may itself serve as the extendable/retractable support attached to the axially displaceable interface. The spring element may comprise, for example, a coil spring which is aligned perpendicularly to the surface of the axially displaceable interface engages the tissue volume. The spring may be covered with a sleeve, shroud, or other containment structure to define a sealed interior for connection to the low pressure source to axially bias displaceable interface against the spring force to pull, elongate, and/or contour the tissue volume captured by the interface surface. 
         [0013]    In a second aspect of the present invention, a system for scanning a breast tissue volume of the patient comprises a table or base having a horizontal surface with an opening therein. The table or base has an upper surface configured to support the patient in a prone position with a breast depending through the opening. An imaging device is disposed below the base and configured to image the breast as it depends through the opening. A vertically displaceable interface has a surface configured to engage tissue surrounding a nipple of the breast, and a low pressure source is configured to apply a low pressure to the surface of the displaceable interface. The low pressure secures the breast tissue to the interface surface, and the vertically displaceable interface is biased to pull, elongate, and contour the breast tissue, typically to “cylindricalize” the breast, while the breast tissue is secured to the interface surface. 
         [0014]    In specific aspects, the imaging device comprises an ultrasonic transducer array, and the system further comprises a receptacle or “well” disposed beneath the opening in the horizontal surface of the base, where the receptacle or well is configured to contain water or other ultrasonically transmissive medium. The ultrasonic transducer array is located within the receptacle or well and is configured to scan breast tissue while the tissue is immersed within the water or other ultrasonically transmissive medium. 
         [0015]    The system for scanning breast tissue typically further comprises a telescoping or other extendable/retractable support having an upper end attached to a side of the displaceable interface opposite the side engaged by the breast tissue and located within the well/receptacle. The extendable/retractable support defines an interior having a variable volume, and the low pressure source is typically connected to apply the low pressure within said interior of the support to draw and engage the breast tissue to the interface. 
         [0016]    The breast tissue scanning system typically further comprises a coil spring element within the interior volume of the extendable/retractable support. The spring element will be expanded or lengthened to position the surface of the axially displaceable interface toward the breast tissue and will typically thereafter apply a spring force that acts against the low pressure or other biasing forces that pull the interface to elongate and cylindricalize the breast. The low pressure source is typically configured to apply a sufficient force to the interface to pull and elongate the breast tissue volume against the spring force of the coil spring element. 
         [0017]    In exemplary embodiments, the imaging device comprises an ultrasonic ring imaging array configured to circumscribe and translate over the breast. The imaging device will typically further comprise a restrictor ring over the ultrasonic ring imaging array, where the restrictor ring circumferentially constricts the breast volume so that breast tissue does not contact the ultrasonic ring imaging array as the ring is translated over the breast. The restrictor ring may have different sizes or shapes as needed, to accommodate different tissue sizes and/or shape to be scanned. 
         [0018]    In a third aspect of the present invention, a method for imaging a patient&#39;s breast comprises locating the patient in a prone position with the breast depending downwardly through an opening in a horizontal patient support surface of a table or other base. A surface of a vertically displaceable interface is engaged against the tissue surrounding the nipple of the breast, and a low pressure is applied to the interface surface to seal the breast to the vertically displaceable interface, and the interface is biased vertically downward to elongate and contour the breast. The breast is then imaged with a device disposed below the horizontal patient support surface while the breast remains contoured. 
         [0019]    In specific aspects of the method, imaging comprises ultrasonic imaging and the breast is immersed in a well or other receptacle containing water or other ultrasonically transmissive medium disposed below the opening in the horizontal surface. The imaging device is typically an ultrasonic transducer ring array located within the well which circumscribes breast to effect the scanning. 
         [0020]    The vertically displaceable interface is supported by a telescoping or other extendable/retractable support located within the well, and the support typically has an upper end attached to a lower side of the displaceable interface. The extendable/retractable support typically has an interior with a variable volume, and a low pressure source may be connected to apply low pressure within the interior of the telescoping support to draw and engage the breast tissue to the interior surface. Typically, a coil spring element within the interior volume of the extendable/retractable support biases the surface of the interface vertically towards the breast tissue prior to engagement. The low pressure source typically applies sufficient force to pull and engage the breast tissue volume against the spring force of the coil spring. Imaging typically comprises circumscribing and translating an ultrasonic ring imaging array over the breast, and the ultrasonic ring imaging array may comprise a restrictor ring which displaces the breast so that breast tissue does not contact the ultrasonic ring imaging ray as the ring is translated over the breast. 
       INCORPORATION BY REFERENCE 
       [0021]    All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which: 
           [0023]      FIGS. 1A -1C  illustrate a breast tomography system of the type that can employ the breast shaping device and tissue restrictor ring of the present invention. 
           [0024]      FIGS. 2A-2C  illustrate a first embodiment of a breast shaping device constructed in accordance with the principles of the present invention. 
           [0025]      FIGS. 3A and 3B  are detailed views of a gel pad and low pressure connector segment used in the breast shaping device of  FIGS. 2A-2C .  FIG. 3A  is a top perspective view with a portion cut-away, and  FIG. 3B  is a bottom perspective view with the low pressure connector segment removed. 
           [0026]      FIGS. 4A and 4B  are detailed views of a telescoping support for the gel pad and low pressure connector used in the breast shaping device if  FIGS. 2A-2C , shown in a vertically extended configuration in  FIGS. 4A  and vertically retracted configuration in  FIG. 4B . 
           [0027]      FIGS. 5A and 5B  illustrate an alternative gel pad and low pressure connector configuration having a flat upper surface to enhance cylindrical shaping of the breast. 
           [0028]      FIGS. 6A-6C  illustrate a tissue restrictor ring constructed in accordance with the principles of the present invention.  FIG. 6A  shows the tissue restrictor ring itself.  FIG. 6B  shows placement of the tissue restrictor ring on a ring imaging transducer relative to a telescoping support supporting the alternative gel pad and low pressure connector configuration of  FIGS. 5A and 5B .  FIG. 6C  shows a variation of the telescoping support supporting with a shaper cup intended to more fully cylindricalize smaller breasts. 
           [0029]      FIGS. 7A-7G  illustrate the steps of using an assembly of the tissue restrictor ring, ring imaging transducer, and improved breast shaping outcome with alternate gel pad of  FIGS. 6A and 6B  in a breast tomography system of the type shown in  FIGS. 1A-1C  to image a breast. 
           [0030]      FIGS. 8A-8D  are breast tomography images taken using a breast tomography system having a breast shaping device in accordance with the principles of the methods of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    The following description of preferred embodiments of the invention is not intended to limit the invention to these preferred embodiments, but rather to enable any person skilled in the art to make and use this invention. 
         [0032]    Referring to  FIGS. 1A to 1C , a breast tomography system  100  of the type that can employ the breast shaping device and the tissue restrictor ring of the present invention comprises an ultrasonic imaging ring array  102  including a plurality of ultrasound emitters  102  and ultrasonic receivers  106 . The ultrasonic imaging ring array  102  may be configured to surround a breast or other tissue volume so that the plurality of ultrasound emitters  102  emits acoustic waveforms  112  toward the volume of tissue. The plurality of ultrasound receivers  106  is configured to receive acoustic waveforms scattered by the volume of tissue, and a processor  108  is configured to generate a tomographic images based on the received acoustic waveforms as described in commonly owned, copending application nos. PCT/US2016/050014; Ser Nos. 14/817,470; 14/811,316; 18/703,746; 14/819,091; 14/208, 181; 14/015,459; and 13/894,202, the full disclosures of which are incorporated herein by reference. The system  100  can further include a display  110  on which the acoustic data and/or generated image rendering can be displayed, such as to a medical practitioner and/or the patient. The ultrasonic imaging ring array  102  is configured to scan vertically to produce an image of the breast B which depends through an opening or aperture  116  (see  FIGS. 7A-7C ) in a table  118  having an upper surface for supporting patient P in a prone position. The breast is immersed in water or other ultrasonically transmissive liquid held in a reservoir enclosure  120  located beneath the table. As described in greater detail below, the breast shaping device and the tissue restrictor ring of the present invention are located within the reservoir enclosure  120 . 
         [0033]    As shown in  FIGS. 2A-2C , a breast or other tissue shaping device (BSD)  130  for positioning a tissue body includes a toroidal pad  132  having an opening  134  for receiving a target region on a tissue body, such as a nipple region N on a breast B. A low-pressure or “suction” source  136  is coupled to the toroidal pad 132  through an interior of, or interior passage within, an extendable/retractable supporting column  138 , which is typically a telescoping column including an upper chamber or segment  138   a,  a middle segment  138   b,  and a lower segment 138   c.  While three segments have been found to be a useful number, it will be appreciated that as few as two or as many as five or more segments might also find use. Other non-telescoping designs, such as accordion designs, could also be employed. In all cases, however, the supporting column should be sufficiently sealed so that the low pressure source coupled to the column can be transmitted into the interior of the column and to the toroidal pad  132 . 
         [0034]    The BSD  130  functions to comfortably immobilize a breast B or other tissue body of a patient, such that the tissue body can be properly scanned e.g., for monitoring, for medical diagnostics, etc. Additionally or alternatively, the BSD  130  can pull breast or other the tissue body away from the body of the patient, e.g., the breast can be pulled away from chest wall of the patient, thereby enabling a larger percentage of the tissue body to be scanned, e.g., for lesions. The BSD  130  can additionally or alternatively function to properly position a breast or other tissue body within a scanning region of an imaging system, thereby increasing efficiency in processing of image data or other data. The BSD  130  can additionally or alternatively function to stretch the tissue body, thereby reducing a thickness of tissue structures (e.g., skin) in order to provide an improved scan of the tissue body. Finally, the BSD  130  can provide a sanitary means for positioning the tissue body, for a scanning system that is used for multiple patients. 
         [0035]    In a specific example, the BSD  130  immobilizes a volume of breast tissue to enable scanning of smaller breasts by elongating and contouring the breast relative to the chest wall to reduce glancing angle effects in relation to incident waves on a tissue surface, enable detection of legions closer to the chest wall by pulling a higher percentage of breast tissue away from the chest wall, improving centering of the breast in a scanning region of interest to reduce computational load in post-processing of scan data ,e.g., with sound speed measurements, with attenuation measurements, with reflection measurements, with time of flight measurements, with density measurements, with stiffness measurements, etc., and induce elongation (e.g., “cylindricalize”) of the volume of breast tissue, thereby inducing a reduction in thickness of skin of the breast to improve scan data. 
         [0036]    The BSD  130  is preferably configured to be used within a volume of an ultrasonically transmissive scanning medium (e.g., water) retained within the reservoir enclosure  120 of the ultrasound tomography system  100 . The BSD  130  properly immobilizes the breast or other tissue body within the scanning medium so that the tissue body can be properly scanned without disturbance caused by tissue buoyancy. As such, the system can interface with embodiments, variations, and examples of one or more elements of the system for providing scanning medium described in U.S. application Ser. No. 14/811,316, entitled “System for Providing Scanning Medium” and filed on 28 Jul. 2015, which is herein incorporated in its entirety by this reference. Additionally or alternatively, the system  100  can interface with embodiments, variations, and examples of one or more elements of the patient interface system configured to support the body of a patient during a scan, as described in U.S. application Ser. No. 14/208,181, entitled “Patient Interface System” which has been previously incorporated herein by reference. However, the BSD  130  for positioning a tissue body described herein can additionally or alternatively interface with any other suitable elements/systems. 
         [0037]    As shown in  FIGS. 3A and 3B , the toroidal pad  132  is formed from a silicone rubber or similar complaint material, and a bottom surface of the toroidal pad  132  is typically attached to an interface plate  140  with a plurality of holes or perforations  142  therein. The opening  134  is configured to receive a target region of the tissue body, such as the region surrounding the nipple N of the breast B, as seen in  FIGS. 1A-1C . The opening  134  will usually have a funnel or conical portion formed in the upper surface of the toroidal pad  132  and functions to comfortably receive ad attach the tissue body during a scan. 
         [0038]    While preferably toroidal, the pad  132  could have other, non-toroidal geometries, such as ovoid, polygonal, and the like. The pad  132  will have a thickness, a top surface, a bottom surface, and opening  134  through the thickness that allows negative pressure to be transmitted to tissue engaged against the top surface and/or received within the opening. Preferably, the dimensions of the pad  132  (in combination with the material properties) provide a pad with a suitable buoyant behavior for scanning applications in a scanning medium used. For instance, the pad  132  can be configured such that it does not float in scanning medium in an undesired manner. In one variation, the footprint of the pad  132  is circular; however, the footprint can alternatively have any other suitable shape (e.g., ellipsoidal, rectangular, polygonal, amorphous, etc.). In one variation, the top surface is approximately frustoconical (e.g., shaped as an inverted funnel) in order to comfortably support a portion of the tissue body. The top surface can alternatively have any other suitable profile (e.g., a profile that is complementary to or matched to a specific tissue body). In another variation, the top surface is substantially planar (although a slight degree of convexity or concavity is acceptable) with low pressure plenums about the periphery. The shape of the bottom surface is less critical, usually being substantially planar; however, in alternative variations, the bottom surface can have any other suitable profile. In one variation, an opening in the bottom surface to connect the low pressure sources is circular and centrally located (e.g., concentric with the inverted funnel of the top surface or configured to branch into plenums about the periphery of the top surface); however, in alternative variations, the opening can alternatively have any other suitable cross section (e.g., ellipsoidal, rectangular, polygonal, amorphous, etc.) and/or be non-centrally located relative to the top surface of the pad  132 . Furthermore, the pad  132  and/or the opening may not have constant cross sections through the thickness of the pad  132 . For instance, the pad  132  can taper in profile from its bottom surface to its top surface, and/or the opening can have a different cross section at the bottom surface in comparison to the cross section of the opening at the top surface, in order to accommodate the reference region of the tissue body and enable immobilization of the tissue body comfortably, by way of the negative pressure generated by the low pressure subsystem  136 . 
         [0039]    In specific examples, the pad  132  has a cylindrical outer surface and has an outer diameter from 0.5 cm to 3 cm; the top surface is an inverted frustoconical surface having a base angle from 5° to 85°, the thickness of the pad is from 1 cm to 5 cm, the bottom surface is substantially planar, and the opening is a circular opening through the thickness of the pad, with a constant cross section having a diameter from 0.5cm to 3 cm. While one opening is described above, the pad  132  can alternatively have multiple openings in order to immobilize the tissue body at multiple points on the surface of the tissue body. In specific examples, the pad  132  is preferably configured as a “one-size-fits-all” element that accommodates a wide variety of breast morphologies; however, the pad  132  can additionally or alternatively be customized to the morphology of each patient being scanned. 
         [0040]    In relation to the top surface and the opening, the reference or target region of the tissue body is preferably a most extreme region of the tissue body (e.g. a region that protrudes or otherwise provides an attachment location such as a nipple on a breast), in the orientation in which the patient interfaces with the pad  132 . In the context of a volume of breast tissue, the reference region can be a most-anterior region of the breast (e.g., the nipple region), such that the nipple region of the breast is retained at the opening of the pad  132  to properly immobilize the breast of a patient who is in a prone position. However, the target or reference region can additionally or alternatively be any other suitable region of a tissue body that facilitates immobilization of the tissue body. 
         [0041]    The pad  132  is preferably composed of a material having a high degree of acoustic transparency, such that the pad does not interfere with proper scanning of regions of the tissue body within the pad  132 . As such, in some variations, the material composition of the pad  132  can thus provide closer focusing at the interface between the tissue body and the pad  132  (e.g., in ultrasound imaging applications). In variations, the pad  132  is composed of a polymeric material (e.g., plastic, hydrogel, etc.), and in specific examples can include a material composed of one or more of: agar, guar bean, and carrageenan; however, the pad  132  can additionally or alternatively comprise any other suitable material (e.g., natural material, synthetic material). For instance, the pad  132  can be composed of a synthetic polymer (e.g., polyurethane) processed to have desired acoustic or other characteristics. The material is preferably substantially stiff, but compliant in supporting the tissue body comfortably; however, the material can alternatively have any other suitable properties (e.g., hardness, stiffness, porosity, transparency, thermal characteristics, optical characteristics, electrical conductivity characteristics, rheological characteristics, etc.). Furthermore, the pad  132  can be configured for single-use applications (e.g., to provide a sanitary option) and/or can be configured to controllably degrade (e.g., in a manner that does not affect fluid handling components of the scanning system) after a certain number of uses in order to prevent repeated uses of the pad  132 . However, the pad  132  can alternatively be configured to be reusable. In a specific example, the pad can comprise a blend of agar, guar bean, and carrageenan, and be configured to have a specific gravity of 1.06 (e.g., slightly heavier than water); however, the pad  132  can have any other suitable composition. 
         [0042]    The interface plate  140  functions to allow the pad  132  to be properly seated at a receiving portion of a low pressure system as described below. In more detail, the interface plate can allow the pad  132  and the opening  134  of the pad  132  to be properly aligned and positioned in relation to the segments  138   a,    138   b,  and  138   c  of the support column  138  for transmission of a low pressure from source  136 , thereby allowing the target region of the tissue body to be drawn into the opening of the pad  132 . 
         [0043]    Referring to  FIGS. 4A and 4B , the lower segment 138   c  of the extendable/retractable support column  138  of the BSD  130  is mounted on or through a bottom plate  146  of the reservoir enclosure  120  of the tomography system  100 . The lower segment 138   c  is connected to the low pressure source  136  ( FIG. 2A ) by a connector  148 . The middle segment  138   b  of the extendable/retractable support column  138  is translatable relative to the lower segment  138   a,  and the upper segment  138   c  is translatable relative to the middle segment  138   b.  During operation, the toroidal pad  132  preferably translates with the upper segment  138   a  to a position that comfortably engages the tissue body, and the target region of the tissue body is preferably retained at the opening  134  of the toroidal pad  132  by way of the negative pressure generated by the low pressure system  136 , such that the tissue body is properly immobilized during scanning (e.g., using a tomography system). The low pressure system  136  thus functions to both (1) generate the negative pressure for retaining the tissue body in position and (2) comfortably support the tissue body at an appropriate position during scanning. 
         [0044]    The segments  138   a,    138   b,  and  138   c  of the column support  138  are preferably substantially cylindrical, having a wall with an appropriate thickness and a longitudinal axis that is parallel to and concentrically aligned with the opening  134  of the pad  132  in assembled system. Furthermore, the upper segment  138   a  is preferably oriented vertically, such that the support column  138  can properly immobilize a tissue body (e.g., volume of breast tissue) for a patient who is interfacing with the BSD  130  in a prone position. However, in alternative variations, the segments  138   a,    13   b,  and  138   c  can have any other suitable shapes (e.g., non-cylindrical, polygonal, prismatic, etc.) and/or orientation that provides proper relative motion between the segments. 
         [0045]    The column  138  including segments  138   a,    138   b,  and  138   c  can be composed of a polymeric material (e.g., a plastic), a metallic material, a composite material, a ceramic material, a glass, and/or any other suitable material. Some or all of the segments  138   a,    138   b,  and  138   c  are preferably configured to support the negative pressures and/or positive pressures implemented in the BSD  130  without deformation. The segments, however, can alternatively have any other suitable composition and/or be configured with any other suitable mechanical properties. In some cases, one or more of the segments  138   a,    138   b,  and  138   c  can include stops configured to define limits of the relative range of motion of the segments. Additionally or alternatively, the expansion range of the segments can be defined in any other suitable manner, as described in more detail below. 
         [0046]    The lower segment  138   c  preferably has a base region and a superior region, wherein the base region is coupled to the base plate  146  of a imaging tank in the reservoir enclosure  120  associated with the tomography system  100 , and the superior region is open to interface with the middle segment  138   b  and upper segment  138   a.  Preferably, the low pressure source  136  connects with the lower segment  138   c  via the connector  148  near the base, but the low pressure source  136  can additionally or alternatively interface with any of the segments at any level in the column. Still alternatively, the low pressure source  136  can interface with an internal portion of the supporting column  138  or can be connected to the opening 134  in the pad  132  by a separate conduit. 
         [0047]    Preferably, the low pressure source  136  can generate a negative pressure of up to approximately 200 mmHg in order to retain the tissue body in a comfortable manner (and as regulated by the U.S. Food and Drug Administration, in some embodiments). In one variation, the low pressure source can provide a negative pressure over a range that includes the range between 100 and 125 mmHg, which, in a specific embodiment, can properly immobilize the tissue body without causing discomfort. However, the low pressure source  136  can alternatively generate pressures over any other suitable range, and can be configured to generate negative pressures and/or positive pressures. Furthermore, the low pressure source  136  can be configured to generate appropriate pressures during different phases of scanning (e.g., in relation to patient preparation, initialization, mid-scan, scan completion, etc.). 
         [0048]    For instance, in some variations, the low pressure source  136  can provide a higher negative pressure (e.g., 125 mmHg) during initialization phases when the tissue body of the patient is first being immobilized; however, once the tissue body is properly immobilized and scanning initiates, the pressure value can be reduced (e.g., to 50 mmHg), thereby increasing comfort while still allowing the tissue body to be effectively retained in position. Finally, when scanning is completed, the negative pressure can be eliminated, or even reversed (e.g., to expel the tissue body from the low pressure subsystem). In relation to varying the low pressure during operation of the system, the low pressure established by the low pressure source  136  can be adjusted manually (e.g., using an external control module). However, the pressure established by the low pressure source  136  additionally or alternatively can be adjusted automatically (e.g., by using pressure sensors that enable coordination between the low pressure source  136  and phases of scanning established by related systems, by using a mechanism that automatically reduces or increases pressure during scanning phases as described in more detail below, etc.). 
         [0049]    The low pressure source  136  can be controlled with any suitable controller and, as such, can have an associated safety mechanism such that a maximum pressure value is never exceeded. In a specific example, the maximum pressure can be 200 mmHg; however, in alternative variations, the maximum pressure can be any other suitable pressure value. The low pressure source  136  can additionally or alternatively include a manual shutoff valve and/or any other suitable shutoff system. 
         [0050]    The column segments  138   a,    138   b,  and  138   c  are configured to be translatable relative to each other in a telescoping manner and the contiguous interiors of the segments coupled the opening  134  of the pad  132  to the low pressure source  136 . In some variations, the telescoping structure can also function as a portion of a mechanism that automatically adjusts low pressures provided by the low pressure source  136 , during different phases of scanning/patient orientation relative to the system. The segments  138   a,    138   b,  and  138   c  are preferably configured to form a sufficiently tight sliding fit such that the interface between the segments prevents a significant low pressure leak from occurring, while still allowing sliding motion between the first and the second chambers  130 ,  140  to occur. 
         [0051]    Preferably, the segments  138   a,    138   b,  and  138   c  are concentrically aligned, such that each segment can provide a telescoping mechanism that allows the tissue body to be properly supported, at the appropriate depth within the scanning tank during scanning. 
         [0052]    In one variation the support column  138  includes a coil spring  150  which is in extension and which pushes the segments  138   a,    138   b,  and  138   c  apart so that the column is in its fully extended configuration, as shown in  FIGS. 2A and 4A . The spring  150  also serves to smooth out oscillations resulting from floatation of the pad  132  in water or other ultrasonically transmissive medium. The spring  150  can also provide an appropriate counterforce to facilitate proper latching of the pad  132  to the coupling interface  150  and/or of the tissue body to the pad  132 . In smoothing out oscillations, the spring  150  can thus contribute to mass-spring-damper behavior of the low pressure subsystem  136  in interfacing with the tissue volume. In variations, the spring has a spring constant from 0.5 to 10 N/cm; however, the spring  150  can alternatively have any other suitable spring constant. As such, in relation to dynamically supporting the tissue body at a suitable depth within the scanning tank, the spring can allow the segments  138   a,    138   b,  and  138   c  to passively provide support, while reducing oscillations when the breast or other tissue body interfaces with the pad  132 , until the tissue body reaches a natural resting state within the scanning tank. 
         [0053]    In similar, but alternative variations, the spring can be replaced with magnetic elements, wherein opposing polarities of the magnetic elements can provide spring-like behavior between the column segments  138   a,    138   b,  and  138   c.  Still alternatively, the segments  138   a,    138   b,  and  138   c  can be configured to translate relative to each other with the assistance of an actuator (e.g., a hydraulic actuator, a linear actuator, etc.) that allows the first and the support column  138  to have expanded and contracted configurations. The support column can alternatively be configured to have expanded and contractions in any other suitable manner. 
         [0054]    As mentioned above, in some variations, the segments  138   a,    138   b,  and  13   c  can also function as a portion of a mechanism that automatically adjusts low pressures provided by the low pressure source  136 , during different phases of scanning/patient orientation relative to the system. In one such variation, the middle segment  138   b  its down stroke, can include appropriate cutout portions that cut off the inlet of the low pressure source  136  into the first chamber  130 , thereby automatically reducing the negative pressure as the tissue body settles into the position in which it is immobilized. Additionally or alternatively, in another variation, motion of one segment relative to another segment can open and/or close a valve associated with the low pressure source  136 , in order to modulate pressure. Other variations of modulating pressure can, however, operate in any other suitable manner. 
         [0055]    In variations, the pad  132  can translate with the upper segment  138   a  as low pressure generated within the column retracts the column and pulls down the target region of the tissue body, such as the nipple region N of the breast B, as shown in  FIGS. 2B  (where the nipple is first attached, reducing pressure within the column) and  FIG. 2C  where the breast is pulled down to a position that comfortably supports the tissue body for scanning. For breast scanning, this pulling cylindricalizes the volume of breast tissue, and draws breast tissue away from the chest wall, such that the tissue body is properly immobilized during scanning (e.g., using a tomography system). 
         [0056]    Referring now to  FIG. 5A and 5B , an alternative interface pad  156  has a flat or planar upper surface  158  which is typically circular with a single hole  161  in the center of the surface. The hole is intended to accommodate a patient&#39;s breast nipple as will be described in detail below. In contrast to toroidal pad  132  described previously which draws the low pressure through a central passage, the interface pad  156  has four annularly placed peripheral plenums  166  to distribute a low pressure about the surface&#39;s periphery. This arrangement allows a larger target region surrounding the patient&#39;s nipple to be secured to the flat surface which in turn improves the cylindricalization of the breast. The peripheral plenums provide improved attached to the peri-areolar region of the breast. In contrast, the smaller low pressure funnel of toroidal pad  132  will shape the breast in a more conical configuration which may be less desirable for overall breast imaging. In some instances, however, the conical breast presentation may allow better visualization of the sub-areolar regions for masses underlying the nipple, e.g., to detect papillomas and other cancerous lesions. 
         [0057]    As best seen in  FIG. 5B , each of the peripheral plenums  160  is connected to a lower opening  170  by curved connecting channels which are formed in between an outer shell  162  and a dome-shaped insert  164 . The interface  156  may thus be molded from any of the polymers described previously in a simple, two-part molding process where the outer shell  162  and insert  164  may thereafter be joined by adhesives, ultrasonic welding, or other conventional techniques. Interface pad  156  may be connected to an expandable/retractable column  138  in the same manner as was described for toroidal pad  132 . 
         [0058]    Referring now to  FIG. 6A and 6B , a restrictor ring or plate  172  may be placed over and attached to the ultrasonic ring imaging array  102  in order to displace breast tissue as the transducer is vertically scanned over the breast, as will be described in greater detail below. The restrictor ring  172  will have an inner aperture or opening  174  which has dimensions which are smaller than those of the inside of the imaging array  102 , thus creating an “overhang” or “offset” to push tissue away from the active inner surface of the array. Typically, the restrictor ring  172  will provide an overhang of at least 1 cm, and typical dimensions for both the restrictor ring and the imaging array are set forth in Table 1 below. 
         [0000]    
       
         
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 BROAD RANGE (cm) 
                 SPECIFIC RANGE (cm) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 d RR   
                 25-30 
                 ~27 
               
               
                   
                 l 
                 12-22 
                 16-20 
               
               
                   
                 w 
                 10-22 
                 12-20 
               
               
                   
                 d o   
                 25-30 
                 ~27 
               
               
                   
                 di 
                 20-25 
                 ~22 
               
               
                   
                   
               
             
          
         
       
     
         [0059]    The restrictor ring  172  will be relatively stiff so that it will not bend or deform when engaging the breast tissue. It will also typically have a relatively thin profile, usually being from 2 to 3 mm thick, to minimize any deleterious effect on imaging. In some cases, the restrictor ring  172  may be made from materials, such as Dekin® polymer, to reduce out-of-plane scattering. The interior opening  174  of the ring  172  may be circular but in many embodiments will be ovoid or tear-shaped with the typical dimensions given in Table 1. Tomography systems  100  may be provided with an inventory of differently sized restrictor plates 172  corresponding to different breast sizes. In this way, an imaging system can be optimized for many women with differing anatomies. 
         [0060]      FIG. 6C  shows an alternative breast shaper concept where a cylindrical cup  182  is secured to an upper surface of a connector disc  180  which in turn is supported on an extendable/retractable support column  138 . The shaper cup  182  may have particular benefit for women with smaller volume breast tissue (e.g., cup size A), whereby even a restrictor ring  172  with the smallest inner diameter (w) and the peripheral suction alternative gel pad ( FIG. 5A /B) would still lead to a conical overall transition from the chest wall to the peri-areolar region. Therefore, shaper cup  182  could virtually encircle nearly all breast tissue of a smaller breast, engage the entire breast with the gentle suction and elongate the breast upon retraction, while providing near-complete cylindricalization of all available breast tissue. This embodiment could also be envisioned for larger breasts as needed. The shaper cup  182  includes an upper portion  184  having a diameter in the range from 10 cm to 20 cm, where the dimensions of the ultrasonic ring imaging array  102  and the restrictor ring  172  are generally in the ranges set forth in Table 1. A smaller transition region  186  is connected directly to the connector disc  180  so that low pressure induced in the column  138 , typically by a recirculating water or other media flow, is transferred to an interior of the upper portion  184 . In this way, the region of the breast B surrounding the nipple N can be drawn into the upper portion  184  where the walls of the cup  182  will cylindricalize the breast for optimized imaging, intervention, and the like. The cup  182  will preferably be formed from an ultrasonically transparent material when ultrasonic imaging is being used. 
         [0061]    Referring now to  FIG. 7A through 7G , a breast tomography system employing both the tissue shaping device and the breast restrictor ring of the present invention will be described. As shown in  FIG. 7A , the interface pad  156  is initially supported on the column  138  in its vertically extended position maintained by the spring force of coil spring  150 . A low pressure is maintained in the interior of support column by a circulating fluid flow  138  maintained by a pump  136  which draws the water or other ultrasonically transmissive medium downwardly through the peripheral plenums  160 . As the patient lowers her breast B through the opening  116  in the table  118 , as shown in  FIG. 7B , the nipple N is received in the center hole  161  of the flat upper surface  158 . As the patient continues to lower her breast, the breast tissue is drawn against the flat surface by the reduced pressure created by the fluid flying through the peripheral plenums  160  until the front region of the breast surrounding the nipple N is flattened against the flat surface  158  of interface pad  156 , as shown in  FIG. 7C . 
         [0062]    Once the breast B is flattened against the flat surface  158  of the interface pad  156 , the pressure within the interior of the support column  138  will be lowered, causing a force which acts against spring  150  which causes the column to vertically retract or collapse, as shown in  FIG. 7D . The force supplied by the pump  136  against the breast B can be controlled in many ways, and the breast will be lowered and elongated by an amount proper to optimize imaging, as shown in  FIG. 7D . 
         [0063]    Once the breast has been properly positioned, the ring imaging array  102  and the restrictor ring  174  will be raised to scan the length of the breast as shown in  FIGS. 7E through 7G . In  FIG. 7E , the circumference of the breast is such that the interior edges of the restrictor ring do not contact the breast. As the assembly of the transducer  102  and ring  172  continues to be raised, as shown in  FIG. 7F , the interior edge of the ring  172  will begin to contact the breast and displace the breast away from the interior of the transducer ring  102 . As the assembly of the imaging array  102  and restrictor ring  174  rises further, as shown in  FIG. 7G , the interior edge of the restrictor ring  174  will significantly displace the breast tissue inwardly, avoiding interference with the imaging function of the array  102 . 
         [0064]    Example images generated with an ultrasonic tomography system equipped with a BSD of the present invention are shown in  FIGS. 8A-8D . 
         [0065]    Embodiments of the system, methods, and protocols of the present invention and variations thereof can be embodied and/or implemented at least in part by a machine configured to receive a computer-readable medium storing computer-readable instructions. The instructions are preferably executed by computer-executable components preferably integrated with the system and one or more portions of a processor and/or a controller. The computer-readable medium can be stored on any suitable computer-readable media such as RAMs, ROMs, flash memory, EEPROMs, optical devices (CD or DVD), hard drives, floppy drives, or any suitable device. The computer-executable component is preferably a general or application specific processor, but any suitable dedicated hardware or hardware/firmware combination device can alternatively or additionally execute the instructions. 
         [0066]    The FIGURES illustrate the architecture, functionality and operation of possible implementations of systems, methods and computer program products according to preferred embodiments, example configurations, and variations thereof. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block can occur out of the order noted in the FIGURES. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions. 
         [0067]    As a person skilled in the art will recognize from the previous detailed description and from the figures and claims, modifications and changes can be made to the preferred embodiments of the invention without departing from the scope of this invention defined in the following claims. 
         [0068]    While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.