Patent ID: 12193886

DETAILED DESCRIPTION

Breast tomosynthesis systems generally include an x-ray source mounted on a rotatable arm of a gantry and an x-ray detector positioned generally normal to the x-ray source when the x-ray source is at zero position. During tomosynthesis image acquisition, the x-ray source is rotated over a limited angular range. At various points in the x-ray source trajectory the source is activated and an image is captured by the detector. Each image captured at each point is referred to as a projection image. Computer programs are used to reconstruct a three dimensional volume from the projection images and the three dimensional volume is used for lesion detection. One example of an x-ray imaging system capable of mammographic and tomosynthesis imaging and which may be adapted to incorporate the present invention is shown inFIG.1.

The mammography/tomosynthesis system is shown to include an acquisition work station (AWS)4and gantry1supporting an x-ray imaging assembly2. Such a mammography/tomosynthesis system is currently available from the common assignee under the trade name Selenia Dimensions, and is representative of merely one x-ray system on which the needle biopsy assembly10of the present invention may be mounted. The gantry1supports a C-arm that can move up or down along the gantry to a selected height, driven by motor(s) controlled by a health professional operating the system. C-arm carries an x-ray tube2aat an upper end and a breast tray2bat a lower end. Tray2bcovers a flat panel x-ray image receptor2c, spaced from the tray by a focused anti-scatter grid2d(which may be retractable so that it can be removed from the space between tray2band receptor2c). The C-arm also carries a compression paddle2ethat is between source2aand breast tray2band is motorized to move away from tray2bso a patient's breast can fit between tray2band paddle2e, and closer to tray2bso the patient's breast can be compressed and immobilized. The movement of paddle2eis motorized and controlled by the health professional. Paddles2eof different size and different configurations can be fitted on the gantry to suit different breast sizes or to suit imaging needs (i.e., for screening or diagnosis). In addition, the health professional can move paddle2ealong the width of tray2bto a position in which paddle2ematches the position of a breast that is not centered on tray2b, as in the Selenia system currently offered by the common assignee. The system further includes other components, such as a control station4comprising interface devices such a keyboard4aand trackball4b, a display screen4c, and control and image processing facilities.

According to one aspect of the invention a needle biopsy assembly10may easily be mounted in between the x-ray source and the x-ray detector of the imaging system2. Unlike previous needle biopsy assemblies, the needle biopsy assembly of the present invention utilizes all of the existing components of the x-ray system, including the compression device and the x-ray detector. As a result, it can be appreciated that the needle biopsy assembly is a low cost solution which makes upright needle biopsy capability available to a variety of current x-ray imaging platforms.

FIG.2illustrates the needle biopsy assembly10in more detail. Support bracket21extends between handles23aand23b, which facilitate transport of the assembly. Guidance module19, mounted on support bracket21, includes components for controlling the movement of the biopsy device15. The biopsy device may be, for example, an Eviva™ vacuum assisted biopsy device manufactured and sold by Hologic, Inc. Fixed support arm17extends from the guidance module to connector31. In one embodiment connector31connects angular support arm12to the fixed support arm17at a fixed angle. Alternative embodiments which include adjustment mechanisms for varying the angle of displacement between the angular support arm and the fixed support arm may be substituted herein as equivalents. Holster mount35is moveably coupled to the support arm. The linear movement may be mechanically controlled (i.e., via the guidance module and associated motors) and/or may be manually controlled using either or both of the thumbwheel knobs33aand33b. The holster mount35includes an attachment mechanism36that is adapted to receive biopsy holster13. The biopsy device15sits within the biopsy holster13. A needle support11may advantageously be coupled to the holster mount for needle stabilization. A control module25may be mounted to either of the handles,23bor23avia clamp36. In various embodiments, each handle may include one or more electrical connectors which enable communication between the clamped control module25and the guidance module19, and the medical professional may move the control module to either handle as a matter of preference. The control module25includes a user interface that enables a medical professional to control the biopsy procedure without the need to leave the patient. The control module includes a display28for displaying a status or other information about the biopsy, and one or more buttons27for controlling the movement of the biopsy device during the procedure.

FIGS.3A and3Billustrate the needle biopsy assembly10mounted on a gantry of an x-ray imaging system. Various embodiments of the needle biopsy assembly may be used with either an upright or prone imaging system, for the purposes of this application an embodiment for use with an upright breast tomosynthesis imaging system (such as the Dimensions™ Breast Tomosynthesis imaging system provided by Hologic, Inc.) is described. An exemplary tomosynthesis imaging system may include a tube head32supporting a cone beam or other x-ray source, and a compression platform30encasing an x-ray detector. The tube head32is rotatably mounted on a gantry (not shown) to enable the tube head to rotate in along an angular trajectory generally designated by the dashed line41inFIG.3B.

In one embodiment the needle biopsy assembly10includes clamps, hooks or other attachment means for mounting the needle biopsy assembly to the gantry of the tomosynthesis imaging system. Advantageously the clamps are mated to features of the gantry that support other attached devices (such as face shields and the like) although such reuse is not a requirement.

In the example ofFIGS.3A and3B, the holster13is coupled to the holster mount on the a fixed angle arm12, and the fixed angle arm12is fixedly mounted on the support arm17at an angle offset from normal by 10 degrees, although it is readily appreciated that the offset angle may vary and is largely a matter of design choice. Angling the arm12(and by consequence the biopsy device15) allows the biopsy device to be advanced to a desired location within a biopsy target area (indicated generally by the target area50) without the biopsy device and holster introducing artifacts into the x-ray image. As shown inFIG.3B, the cone beam x-ray source will extend into the target area50, but the device15does not fall within the cone beam. It should be noted that although a 10 degree fixed angle is disclosed, the present invention is not limited to any particular fixed angle and it is appreciated that the selected fixed angle may differ in response to particular geometries of the imaging systems and tissue removal tools. In a broadest sense, the present invention encompasses the idea of angling a biopsy needle to limit the introduction of visual artifacts caused by the needle during x-ray imaging.

FIG.4is a side view of an exemplary embodiment of a needle biopsy assembly of the present invention. InFIG.4, line A is within a plane that is ‘normal’ to the plane of the x-ray detector30. Line B illustrates the angular displacement of the biopsy device, and therefore the device is offset from the normal by an angular measure of 0. As a result the biopsy device will interfere with biopsy imaging.

Also shown in more detail inFIG.4are exemplary coupling mechanisms50aand50bof the needle biopsy assembly10. The coupling mechanisms50aand50bare adapted to mate with complementary features of the gantry. Other types of coupling mechanisms, including latches, hooks, slots and the like may be readily substituted herein as equivalents.

FIG.5is a top down view of the exemplary embodiment of the needle biopsy assembly, shown with only a subset of components labeled for ease of reference. When viewing the needle biopsy assembly from this perspective, the displacement N of the needle tip which results from the angular tilt of the biopsy device is readily apparent. This view best illustrates the ability of this device to biopsy areas of the breast (such as the axilla tissue and tissue near the chest wall) which were previously difficult to access using prior art stereotactic devices.

FIGS.6A through6Cillustrate various compression paddles which may be used with the present invention. In contrast to prior art needle biopsy compression paddles, which were generally fabricated of radio-opaque material having an opening therethrough for accepting the biopsy needle, the compression paddles62A-62C are preferably radiolucent. Slots64aand64bare positioned to enable the compression paddle to be removably coupled to the compression device of the x-ray imaging system, allowing the paddles to easily be exchanged with the mammography/tomosynthesis paddles used for breast cancer screening. The biopsy compression paddles may be manufactured in different sizes to be used for different sized breasts, as shown inFIGS.6B and6C. An opening66is provided in each biopsy compression paddle. The opening enables the portion of the breast associated with the target to be exposed. As shown inFIG.7, the portion68of the compression paddle62athat surrounding the opening66is shaped to increase the compression on the portion of the breast being biopsied, thereby stabilizing the biopsied area.

One advantage of using the radiolucent breast compression paddle is that it allows full view of the detector; in prior art needle biopsy arrangement, only a portion of the detector associated with target localization was visible. This was sufficient because prior art biopsies were only performed on that portion of the tissue which was immediately below the opening in the compression paddle. However, the tilted needle of the present invention increases the amount of tissue that is available for biopsy beyond the border of the compression paddle opening—the needle in fact has the reach N shown inFIG.5. Thus, as mentioned above, axilla tissue and tissue close to the chest wall can more readily be excised during biopsy.

FIG.8illustrates a 2D image of a breast taken with a radiolucent biopsy paddle such as those shown inFIGS.6and7. As shown inFIG.8, one advantage of the radiolucent compression paddle is that the entire detector image may be viewed at the acquisition workstation interface; the radiologist is no longer limited in their access to information. As a result, the radiologist may see that portions of a lesion80extend beyond the compression paddle opening66. This portion of the breast can be accessed using the tilted biopsy needle assembly of the present invention to ensure that all tissue is accessed for proper diagnosis.

Exemplary needle biopsy assemblies such as that described above may be generally used as follows. A patient who has been identified as a candidate for biopsy is positioned at the x-ray imaging system. At step91the biopsy compression paddle moves down towards the compression platform, compressing the patient's breast, and the process of visualizing the lesion is initiated at step92. As mentioned briefly above, depending upon the capabilities of the x-ray imaging system, visualization of the lesion may be performed using a scout image, a mammogram, acquired stereotactic images, acquired tomosynthesis projection images, tomosynthesis reconstructed images, or any combination thereof. In one embodiment, an x-ray imaging system having tomosynthesis capabilities may be adapted to include a ‘stereotactic mode’, which, when selected, causes the x-ray imaging system to automatically retrieve the typical +/−15 degree stereotactic images and performs appropriate imaging processing on the stereotactic images to derive a stereotactic volume. One advantage of such an embodiment is that patient exposure may be reduced in tomosynthesis systems which use lower doses during projection image acquisition.

Once the lesion has been visualized, at step93the lesion is targeted. Targeting the lesion involves identifying the coordinates of the lesion using image data, and converting the coordinates from the Cartesian coordinate system of the images to the angular coordinate system of the tilted biopsy assembly using conversion techniques known to those of skill in the art. According to one aspect of the invention, different images, or combinations of images, may be used for visualizing the lesion than are used for targeting the lesion. For example, assume that a scout image is initially used to ensure that the patient is in position, and a pair of stereotactic images are used to visualize the lesion. If the lesion is found in the scout image, but not in both stereo images, the scout may be used in combination with the stereotactic image in which the lesion is located to derive target location information. Therefore, as above, depending upon the capabilities of the x-ray imaging system, the lesion target coordinates may be derived using a scout image, a mammogram, acquired stereotactic images, acquired tomosynthesis projection images, tomosynthesis reconstructed images, or any combination thereof.

At step94, once the target coordinates are derived the medical professional can being the biopsy procedure by pressing control buttons required to move the biopsy needle.FIG.10illustrates an exemplary display and buttons of a control unit25. The control unit includes a display28for displaying information related to the biopsy, such as information regarding needle size, distance to platform and paddle, needle coordinates, target coordinates, proximity to target and other related information. The control panel may also provide other helpful information to the user, such as warning indicators when the needle is too close to the breast platform, chest wall or skin line. As mentioned above, the warning indicators may be color coded or may provide other visual or audible indicators of undesirable conditions.

As mentioned above, in one embodiment the control unit also includes buttons (including button27) positioned and arranged to allow single handed activation of the biopsy assembly while precluding accidental activation. In one embodiment, a pair of control buttons is provided, one on the front face of the control panel, and another on the back face of the control panel. Biopsy assembly movement may only be activated via simultaneous depression of both buttons. Other mechanisms for affirming operator intent may be substituted herein without affecting the scope of the invention.

According to one aspect of the invention, mechanical stops may be introduced into the biopsy path to stop automated needle movement at particular points along the path. For example, it may be desirable to switch to manual control of the needle movement, i.e, via knob33aor33bwhen the needle is within a desired range of the target. Or it may be desirable to provide a release brake for slow insertion of the needle into the breast. According to one embodiment, the number and location of mechanical stops is a programmable function which may be tailored to the individual preferences of a user of the system. Suffice it to say that numerous methods for mechanical advancement of the needle, including geared advancements, piston advancements, etc. are envisioned.

Returning now toFIG.9, at step95once the needle has been advanced to the target coordinates, an image may be acquired to verify that, in fact, the needle is positioned at the lesion. As the biopsy needle is out of the view of the x-ray imaging system such image may be obtained without interference. At step96, when it is verified that the needle is at the target, the tissue may be excised, and the biopsy is complete. Although not explicitly shown in the flow diagram, steps95and96may be repeated to verify excision of the entire lesion.

Accordingly a biopsy needle assembly has been shown and described. According to another aspect of the invention, a user interface of the acquisition workstation is advantageously augmented with needle biopsy control capabilities, An example of user interface features that may be added to an acquisition workstation for use with the needle biopsy assembly is shown inFIG.11. The user interface includes menus and/or control buttons or icons which enable the radiologist to control the display and output of information gathered during the biopsy. Targeting tools110allow the user to review, modify and delete target information. Image source selectors120(including stereotactic, tomosynthesis, scout, mammography, etc.) allow the radiologist to select which images to use for visualization or targeting. Image view selectors130allow the radiologist to quickly pull up and view any of the images that may have been acquired during the biopsy. Any of the images may be pulled up in the image window150. Other information related to the biopsy, such as the type of biopsy device, the relative distances between the target and the compression plate/platform, etc., may also be included on the acquisition workstation. It should be noted that although a particular arrangement of buttons and icons has been shown in the representative view ofFIG.11, the present invention is not limited to any particular representation of such information, and other forms of pull down menus, hyperlinks, icons, buttons, and windows are considered equivalents hereto.

Although the above embodiments have described and illustrated a needle biopsy assembly for obtaining cores when the needle is positioned in a general cranial caudal orientation over the breast, according to one aspect of the invention lateral access to the breast may be achieved through the attachment of a lateral biopsy arm. The ability to perform lateral biopsies is particularly important for patients with thin breasts, as compression may reduce the thickness of the breast to such a degree that the tissue excision port at the distal tip of the biopsy needle cannot be fully inserted into the tissue.FIGS.12A-12Cillustrate various views of an embodiment of the needle biopsy assembly of the present invention that has been augmented with a lateral biopsy arm200.FIG.12Ais a straight on view of the augmented assembly,FIG.12Bis a perspective view of the augmented assembly whileFIG.12Cis a side view of the augmented assembly. The lateral biopsy arm supports the biopsy needle along a line substantially parallel to the detector, thereby permitting lateral excision of breast tissue. In the embodiment ofFIGS.12A-12C, the lateral biopsy arm includes a holster mount plate210and a thumb wheel220. Rotation of the thumb wheel220results in manual translation of the needle in the direction indicated generally as X inFIG.12A. Although manual translation in the X plane is shown, it is appreciated that motorized translation may be achieved by extending control from the guidance module19to the holster plate210.

Targeting of the lesion, which defines how far the needle should move in the X,Y and Z direction is always done assuming that the needle is in a cranial-caudal orientation. According to one aspect of the invention, an electrical connection on the holster mount mounts with a connector on the lateral biopsy arm when the lateral biopsy arm is coupled to the holster mount13to enable the guidance module19to adjust the guidance coordinate system as appropriate for proper lesion localization.

Accordingly a tilted needle biopsy assembly having numerous advantages has been shown and described. Because the biopsy needle is angled relative to at least one of the detector and the x-ray source, x-ray imaging may be performed during the biopsy procedure without interference by the biopsy device. In addition the angled biopsy needle allows improved access to the axilla and chest wall of the patient. The stereotactic biopsy device of the present invention may be coupled to any x-ray system, whether upright or prone, including but not limited to mammography systems, tomosynthesis systems, and combination mammography/tomosynthesis systems. The system flexibly supports the use of any mode of image capture (i.e., scout, two dimensional mammogram, three-dimensional reconstructed volume) for either or both target visualization and target localization. With such an arrangement, a needle biopsy assembly having improved patient coverage is provided for use with a variety of different x-ray imaging platforms.

Having described exemplary embodiments, it can be appreciated that the examples described above are only illustrative and that other examples also are encompassed within the scope of the appended claims.