AU2008201638B2 - Device for cushioning of compression surfaces in mammograph - Google Patents

Description

S&F Ref: 607618D2 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name and Address BioLucent, LLC, of 35 Crosby Drive, Bedford, of Applicant : Massachusetts, 07130, United States of America Actual Inventor(s): George D. Hermann, Thomas A. Howell, Gail Lebovic, David Willis Address for Service: Spruson & Ferguson St Martins Tower Level 35 31 Market Street Sydney NSW 2000 (CCN 3710000177) Invention Title: Device for cushioning of compression surfaces in mammograph The following statement is a full description of this invention, including the best method of performing it known to me/us: 5845c(1200568_1) DEVICE FOR CUSHIONING OF COMPRESSION SURFACES IN MAMMOGRAPH BACKGROUND OF THE INVENTION 5 The present invention relates generally to medical apparatus and methods and more particularly to devices and methods for cushioning or padding the surface of compression plates applied to body parts for purposes of obtaining x-ray films, for example,.mammography, or other scans of compressed tissue. 10 Currently, in the case of mammography, a patient's breast is placed under compression by opposing plates attached to a mammography machine. Once under compression an x-ray is .taken to determine the presence or absence of suspect lesions in the breast tissue (e.g. calcifications, tumors). Approximately 25 million screening mammograms are performed yearly, which is estimated to be only a 50% compliance rate among potential patients, meaning iS. that number would double if all potential patients complied with the recommended screening regime. One of the more common complaints from mammography patients is discomfort during compression of the breast. Most patients can only tolerate up to 10-11 compression units. The current legal limit for clinical mammography is 16-18 units. A device which would reduce discomfort could likely improve compliance for screening. An important reason for compressing the breast during mammography is to provide a thinner cross section of tissue for the x-rays to pass through. When the breast is compressed, it provides optimal imaging of the tissue abnormalities with the lowest possible dose of x-ray radiation to the patient. Furthermore, during a mammogram, it is important for the x-ray plate to 25' be free from radiopaque material, so that the diagnostic film, once processed, can give the physician the best possible picture of the tissue and any abnormalities.

2 Although patients may tolerate the pain during compression, there is a need for improved devices and techniques to provide better screening outcomes by enabling the use of higher compression force, and by providing increased patient comfort during mammograms thereby positively impacting patient compliance with mammographic 5 screening and ultimately impacting early detection of cancer and improving patient survival. Such improved devices must be radiolucent and made of a relatively homogeneous material to avoid striations or other variations on the resulting x-ray image, have a low profile to allow for correct positioning of the breast in the mammography 10 machine, be easily cleaned or disposable for sanitary reasons, and provide structural support and tactile comfort to the patient (both soft to touch and providing a less harsh or "cold" surface). In addition, such improved devices will permit the use of higher compression forces to be applied to the breast during mammograms without the patient reaching her tolerance level for discomfort, resulting in a thinner tissue section, better is image quality, and reduced x-ray dose to the patient. DESCRIPTION OF THE BACKGROUND ART Various patents have issued illustrating inventions in the field of mammography and comfort during x-ray imaging. For example, in the field of mammography, US Patent Nos. 3,963,933, 4,691,333, 4,943,986, 5,189,686, 5,553,111 and 5,398,272 describe 20 various fixtures useful for breast compression. Further, patents have issued describing devices for increasing comfort during general x-ray procedures, such as US Patent No. 5,226,070 (radiolucent x-ray mat), US Patent No. 5,081,657 (buckey warmer for mammography machine), US Patent 5,541,972 (disposable padding device for use during mammography) and US Patent No. 5,185,776 (padded cover for x-ray cassette). 25 OBJECTS OF THE INVENTION It is the object of the present invention to overcome or ameliorate one or more of the disadvantages of the prior art, or at least to provide a useful alternative. SUMMARY OF THE INVENTION In one aspect, the present invention provides a compression device for an 30 imaging unit, comprising: a compression plate having a compression surface in an x-ray field of the imaging unit and a front surface; and 3 a radiolucent comfort element releasably attached to the compression surface and the front surface, the radiolucent comfort element producing no significant visual artifact on an x-ray while in use. In another aspect, the present invention provides a compression device for an s imaging unit, the device comprising: a compression plate having a compression surface in an x-ray field of the imaging unit and a front surface; a radiolucent comfort element having a first and second surface, the radiolucent comfort element producing no significant visual artifact on an x-ray image while in use; 10 and means for releasably attaching the first surface of the radiolucent comfort element to the compression surface and the front surface. In another aspect, the present invention provides an imaging device, comprising: a vertically oriented base; is an x-ray source on the base; a first compression device comprising the compression device of any preceding claim; a second compression device comprising a second compression surface in the x ray imaging field; and 20 the radiolucent comfort element of any preceding claim releasably attached to the compression surface and the front surface of the first compression device. In another aspect, the present invention provides a method for imaging a breast using an imaging unit including a compression plate, comprising: providing a radiolucent comfort element on a compression surface of the 25 compression plate in an x-ray field of the imaging unit and a front surface of the compression plate; compressing a breast using the compression plate, the radiolucent comfort element deforming under forces applied during compression to provide comfort; and obtaining an x-ray image of the compressed breast, the radiolucent comfort 30 element producing no significant visual artifact on x-ray image. In another aspect, the present invention provides a method for imaging a breast using an imaging unit including a compression plate, comprising: installing a radiolucent comfort element on a compression surface of the compression plate in an x-ray field of the imaging unit and a front surface of the 35 compression plate; 3a compressing a breast using the compression plate, the radiolucent comfort element deforming under forces applied during compression to provide comfort; obtaining an x-ray image of the compressed breast, the radiolucent comfort element producing no significant visual artifact on the x-ray image; and s removing the radiolucent comfort element from the compression plate. In another aspect, the present invention provides a method for performing mammography using a mammography unit including a pair of opposing compression plates, the method comprising: installing a radiolucent comfort element on a compression surface of each of the io compression plates in an x-ray field of the mammography unit and front surface of each of the compression plates; compressing a breast between the compression plates, the radiolucent comfort elements deforming under forces applied during compression to provide comfort; obtaining a mammogram of the compressed breast; and 15 removing the radiolucent comfort elements from the compression plates. In another aspect, the present invention provides a method for performing mammography using a mammography unit including first and second compression devices, the first compression device comprising a compression surface in an x-ray field of the mammography unit and a front surface, the method comprising: 20 installing a radiolucent comfort element on the compression surface and the front surface of the first compression device; compressing a breast between the first and second compression devices, the radiolucent comfort element providing comfort; and obtaining a mammogram of the compressed breast, the radiolucent comfort 25 element producing no significant visual artifact on the mammogram. The present invention, at least in its preferred form, provides greater patient comfort, thereby increasing screening compliance (e.g. patient willingness to have more regular mammograms by reducing discomfort of the procedure). Greater patient comfort also reduces the risk of patient movement (voluntary or involuntary). Motion artifact, 30 caused by patient movement or slippage of the tissue, can result in loss of clarity of the mammographic image. The present invention, at least in a preferred form allows for the use of an increased compressive force, for example, up to 16-18 compression units or more thereby providing for a thinner cross-section of breast tissue during the mammogram resulting in an enhanced ability to detect abnormalities in the 35 mammographic image.

3b The present invention, at least in a preferred embodiment provides for cushioning or providing other patient comfort surfaces on devices used for compressing the patient's tissue, such as radiography machines, fluoroscopy units, mammography units and the like. 5 In a preferred embodiment of the present invention a pad assembly is provided consisting of a pad element, an adhesive layer and a release paper layer allowing for temporary attachment to the applied surface (either the mammography paddle, x-ray plate or directly to the patient's skin). An alternative embodiment of the present invention includes a reusable 10 cushioned paddle configured of a self-skinned foam to allow for easy cleaning between patients. This embodiment may be replaceable after many uses or formed integrally wherein the padded surface and the compression paddle are assembled as one unit. The present invention may also incorporate a dispensing unit for access to single pads for g~ single use. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a typical mammography unit having a base and a pivoting x-ray unit to attached thereto, the x-ray unit including a compression paddle and an x-ray plate. FIGS. 2A-2B illustrate detailed construction of the x-ray plate and the compression paddle respectively. FIGS. 3A-3C illustrate various configurations of compression paddles utilized during mammography in a standard mammography machine; the shape and size depending both on the patient's anatomy and the type of x-ray view desired by the physician. FIGS. 4A-4B illustrate various attachments that can be placed on the x-ray plate to 2.0 enhance the image, including devices for spot compression and magnification. FIG. 5 illustrates a compression paddle and x-ray plate configured for use in a stereotactic biopsy procedure. 2g FIGS. 6A-6C illustrate the pad of the present invention having a padding layer, an adhesive layer and a release paper layer. FIGS. 7A-7B illustrate the installation of the pad of the present invention on an x-ray plate. 4 FIG. 8 illustrates the installation of the pad of the present invention on a compression paddle. FIG. 9 illustrates various pad configurations and geometries according to the present $ invention depending on the type of compression paddle or x-ray unit used in a given procedure. FIG. 10A illustrates an alternative embodiment of the present invention, showing the use of a self-skinned foam fastened to a compression paddle intended for use on multiple patients. 10 FIGS. 10B-1 OC further illustrate an alternative embodiment of the present invention wherein the pad and compression paddle are integral as one unit. FIG. I OD illustrates an alternative embodiment of the present invention, wherein the pad and x-ray plate are integral. Is FIG. 11 illustrates a further feature of the present invention, namely a dispensing unit for storing and dispensing the disposable pads of the present invention to promote ease of use and efficiency. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical or standard mammography unit used to image the breast while under compression is shown in Fig. 1. This unit 10 includes a base 12 and a rotating x-ray source 11, comprising an x-ray source 13, a movable compression paddle 14 and an x-ray plate 15 that 26' holds the film cassette (not shown) as well as serving as a compression surface against which the compression paddle 14 can compress tissue, e.g., a breast to be imaged. As depicted in Fig. 2A, typically the x-ray plate 15, in certain configurations known as a "bucky," is stationary and 5 includes an opening 16 into which an x-ray cassette 17 is placed prior to imaging. The x-ray plate has two. patient contact surfaces, a fiont face 18, and a functional surface 19. The x-ray plate 15, may optionally include radiopaque markers 19A at the perimeter of the functional surface 19 to allow various marking schemes to be utilized during a procedure. Fig. 2B illustrates a more detailed configuration of compression paddle 14, including a front patient contact surface 20 and a functional patient contact surface 21. Paddle 14 is typically constructed of a clear radiolucent plastic material and is designed to be removably attached by an interchange assembly 22, to the movable working arm of the mammography W machine (not shown). These paddles are configured in various geometries as depicted in Figs. 3A-3C to accommodate various patient anatomies and specific needs of mammographers, such as coned compression paddles (3A), spot compression paddles (3B) and the axillary paddle shown as Fig. 3C, all configured to attach to the mammography unit through standard interchange assembly 22, as shown earlier. Similarly, the x-ray cassette holder may be adapted by various ancillary modules such as the spot compression fitting 41 shown in Fig. 4A, and a magnification fitting 42 shown in Fig. 4B. The entire compression system (compression paddle and x-ray plate) can further be modified to accommodate a stereotactic biopsy procedure as illustrated in Fig. 5. In this 2o configuration, compression paddle 14 is modified to include a window 51, allowing the clinician access to the breast, while still under compression, for purposes of placing a device to identify a specific location in the breast, or to perform a biopsy of tissue. A preferred embodiment of a pad assembly constructed in accordance with the present 25 invention is illustrated in Fig. 6A. The pad assembly 60 comprises a padding element 61, an 6 adhesive layer 62, and a release paper 63 to be removed from contact with the adhesive layer just prior to installation on the surface to be padded. Pad element 61 may be constructed of various materials having the following characteristics: produce no significant visual artifact on the mammogram (i.e. is radiolucent), be deformable under the forces applied during compression to S provide comfort. Furthermore, the material should provide conformance to the tissue and the compression surface so as to reduce the propensity for the material to create air pockets or folds that may be of sufficient size to be visible on the x-ray image. Additionally, it may be desirable for the material to be absorptive to external fluids such as sweat. 10 Such materials may be an elastomer or gel, open (reticulated) or closed (non-reticulated) cell foam consisting of polyolefin, or, preferably, a polyurethane open cell foam because of its radiolucent characteristics and soft tactile feel. Of particular advantage is polyurethane foam having a density of 5-6 lbsJcu ft, with approximately 90 pores per inch. The padding material 61 may be a thickness of.050" to .500", preferably in the range of .200" and .250". If an adhesive 36 layer is used, adhesive layer 62 may be one of a variety of currently available pressure sensitive adhesives such as acrylic or synthetic rubber based adhesives, to allow sufficient tackiness for secure attachment to the compression surface, while also allowing for easy removal (e.g. leaving no detectable residue of adhesive on the applied surface) and disposal. Alternatively, a non-adhesive gel may be used to secure the pad or another layer of material having a greater 2.0 coefficient of friction against the applied surface. It is also anticipated by the scope of the present invention that the pad element may itself be textured such that it is sufficiently "tacky" to enable its use without an adhesive layer, i.e., by means of friction between the element and the tissue and the unit compression surface. 7 The pad element of Fig. 6A can be configured with adhesive on the entire surface of the pad, or at certain regions such as just along the border (see Fig. 6C). Fig. 6B depicts a "peel away" packet configuration to house the pad assembly, optionally, the peel away packet can serve as a stiffening element to aid installation of the pad by keeping it in a planar configuration S- to minimize the possibility of misapplying the pad (leading to inadvertent air pockets or folds in the material, etc.) and to aid in positioning the pad prior to adhering it to the applied surface. Fig. 7A illustrates, in stepwise fashion, the installation of the pad assembly 60 of the present invention onto the film holder 15. The first step comprises opening the packing material o housing the pad assembly 60 (S1), and thereafter removing any release paper 63 therefrom (S2). The pad assemblies can be packaged individually or in bulk. Installation on the patient contact surfaces of the x-ray plate 15 are shown in steps S3 and S4, S3 showing the placement of the pad element 61 on functional surface 19, and optionally extending tQ front face surface 18. The installed pad is depicted in Fig. 7A. Fig. 7B shows an alternative embodiment of pad element 61 'C installed onto an x-ray plate where the pad is configured to stretch over side face.23 of the x-ray plate, to provide added comfort for the patient More particularly, the pad of this embodiment includes an adhesive layer which is preferably of a three part construction: a high tack, high peel permanent adhesive securing the adhesive layer to the pad element, a low tack, removable adhesive for securing the adhesive layer to the patient contact surface of the x-ray plate, and a 20 stretchable carrier material between the two adhesives, such as polyethylene. A pad according to the present invention can also be formed of a similar construction using, e.g., polyester as a carrier material. Finally, the pad element may be removed and disposed of and the sequence repeated for the next patient. It may be desirable to score or otherwise provide a fold in the pad 8 element at a fixed point from the edge of the pad to accommodate folding the pad onto the front and/or side face of the applied surface. A similar sequence of steps (SI to S4) is illustrated in Fig. 8A showing the installation of 3 pad assembly 60 of the present invention onto compression paddle 14. The pad assembly (PA) of Fig. 8B is configured such that portions of the pad extend to cover side surface 24 of the compression paddle, providing added comfort for the patient. It should be noted that the pad of the present invention may be installed on the x-ray plate to 15 and the compression paddle 14, or one and not the other, and further optionally on the front face and/or side face of either surface depending on the amount of additional cushioning desired. In experimentation with the present invention, increased comfort was noted in all of the-various configurations as compared to unpadded compression surfaces. An alternative technique for use of the pad is to attach it to the breast of the patient instead of on the mammography machine itself. In this technique (not shown) the release paper is removed and the adhesive side of the pad is placed directly on the breast in an area of tissue to be compressed prior to placing the breast into the mammography machine. 20 Typical geometries of the present invention are illustrated in Fig. 9, including pad elements for x-ray plate 15 (G1), pad elements with windows for stereotactic use (G2), spot compression paddles (G3), coned compression paddles (G4), and axillary paddles (G5). It is noted that while these configurations reflect the geometries of various-commercially 25 available compression paddles and x-ray cassette holders, the present invention may be manufactured in a wide array of sizes and shapes. The present invention includes pad 9 assemblies, where the pad elements are modular (e.g. using more than one pad to cover a desired surface), or cut to fit the desired surface (oversized with an overlay pattern to guide the operator in cutting the pad to fit). An alternative embodiment of the present invention is illustrated in Figs. IOA-IOC. Fig. 1 OA shows a modular configuration of the present invention wherein the pad assembly is constructed from a self-skinned foam (PA), i.e., foam having an impermeable membrane covering, such as a vinyl, deployed over a frame (not shown) and fastened to a compression paddle by suction cups, magnets rivets or adhesive (AD) on the non-functional surface of the t0 compression paddle or x-ray plate. The self-skinned configuration of the pad assembly allows for washing or disinfecting and can therefore be applied for multiple patients. Fig. lOB illustrates a pad assembly (PA) attached to the paddle on the nonfunctional surface by snaps or rivets 110. Fig. IOC further illustrates an alternative embodiment of the I6 present invention wherein the pad 120 and compression paddle 121 are a single integral unit. Fig. 1OD illustrates an alternative embodiment of the present invention wherein pad 122 and x ray plate 123 are a single integral unit. Fig. 11 illustrates a dispensing unit according to the present invention for housing and 20 dispensing the inventive pad assemblies. Dispensing unit 100 includes a housing 101 allowing multiple pad assemblies 103 to be stacked for compact storage, and an access slot 102 for allowing the user to access one pad assembly at a time. The pad assemblies as shown are individually packaged. Alternatively, pad assemblies maybe packaged in bulk (e.g., 25 pads per bag/4 bags per case) for ease of storage at the user location. 10 While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, the above description should not be taken as limiting the scope of the present invention. 11

Claims (33)

1. A compression device for an imaging unit, comprising: a compression plate having a compression surface in an x-ray field of the imaging unit and a front surface; and a radiolucent comfort element releasably attached to the compression surface and the front surface, the radiolucent comfort element producing no significant visual artifact on an x-ray while in use.

2. The device of claim 1, wherein the comfort element comprises first and second surfaces, and an adhesive layer on the first surface for releasably attaching the comfort device to the compression surface and the front surface.

3. A compression device for an imaging unit, the device comprising: a compression plate having a compression surface in an x-ray field of the imaging unit and a front surface; a radiolucent comfort element having a first and second surface, the radiolucent comfort element producing no significant visual artifact on an x-ray image while in use; and means for releasably attaching the first surface of the radiolucent comfort element to the compression surface and the front surface.

4. The device of claim 2 or 3, wherein the compression plate comprises one of a mammography paddle and a bucky.

5. The device of any one of claims 2 to 4, wherein the means for releasably attaching comprises an adhesive layer on the first surface of the radiolucent comfort element.

6. The device of claim 2 or 5, wherein the adhesive layer comprises a pressure sensitive adhesive having sufficient tackiness for secure attachment to the compression surface while leaving no detectable residue when removed from the compression surface. 13

7. The device of claim 2, 5, or 6, wherein the adhesive layer comprises permanent adhesive securing the adhesive layer to the radiolucent comfort element and a removable adhesive for securing the adhesive layer to the compression plate.

8. The device of any one of claims 2 and 5 to 7, wherein the adhesive layer covers the entire first surface.

9. The device of any one of claims 2 and 5 to 7, wherein the adhesive layer covers only certain regions of the first surface.

10. The device of claim 9, further comprising wherein the adhesive layer extends along a border of the first surface.

11. The device of any preceding claim, wherein the compression plate comprises an x-ray cassette holder comprising an imaging area, a first side surface comprising a first opening adapted to permit a mammography unit cassette to pass therethrough, a second side surface opposite the first side surface, and a front surface; and the radiolucent comfort element is releasably attached to the imaging area and the front surface of the x-ray cassette holder.

12. The device of claim 11, wherein the x-ray cassette holder further comprises a support member for attaching the x-ray cassette holder to a mammography unit.

13. The device of any preceding claim, further comprising an impermeable membrane covering the radiolucent comfort element.

14. The device of any preceding claim, wherein the radiolucent comfort element comprises foam.

15. The device of claim 14, wherein the radiolucent comfort element comprises an open cell foam. 14

16. The device of claim 14 or 15, wherein the radiolucent comfort element comprises polyurethane foam.

17. The device of any preceding claim, wherein the radiolucent comfort element comprises a window for stereotactic use.

18. The device of any preceding claim, wherein the radiolucent comfort element has a thickness between about 0.050 inch (1.27 mm) and 0.500 inch (12.7 mm).

19. The device of any one of claims I to 17, wherein the radiolucent comfort element has a thickness between about 0.200 inch (5.08 mm) and 0.250 inch (6.35 mm).

20. An imaging device, comprising: a vertically oriented base; an x-ray source on the base; a first compression device comprising the compression device of any preceding claim; a second compression device comprising a second compression surface in the x ray imaging field; and the radiolucent comfort element of any preceding claim releasably attached to the compression surface and the front surface of the first compression device.

21. The imaging device of claim 20, wherein the imaging device comprises one of a radiography machine, fluoroscopy unit, and a mammography unit.

22. The imaging device of claim 20 or 21, further comprising a second radiolucent comfort element on the second compression surface.

23. A method for imaging a breast using an imaging unit including a compression plate, comprising: providing a radiolucent comfort element on a compression surface of the compression plate in an x-ray field of the imaging unit and a front surface of the compression plate; compressing a breast using the compression plate, the radiolucent comfort element deforming under forces applied during compression to provide comfort; and 15 obtaining an x-ray image of the compressed breast, the radiolucent comfort element producing no significant visual artifact on x-ray image.

24. A method for imaging a breast using an imaging unit including a compression plate, comprising: installing a radiolucent comfort element on a compression surface of the compression plate in an x-ray field of the imaging unit and a front surface of the compression plate; compressing a breast using the compression plate, the radiolucent comfort element deforming under forces applied during compression to provide comfort; obtaining an x-ray image of the compressed breast, the radiolucent comfort element producing no significant visual artifact on the x-ray image; and removing the radiolucent comfort element from the compression plate.

25. A method for performing mammography using a mammography unit including a pair of opposing compression plates, the method comprising: installing a radiolucent comfort element on a compression surface of each of the compression plates in an x-ray field of the mammography unit and front surface of each of the compression plates; compressing a breast between the compression plates, the radiolucent comfort elements deforming under forces applied during compression to provide comfort; obtaining a mammogram of the compressed breast; and removing the radiolucent comfort elements from the compression plates.

26. A method for performing mammography using a mammography unit including first and second compression devices, the first compression device comprising a compression surface in an x-ray field of the mammography unit and a front surface, the method comprising: installing a radiolucent comfort element on the compression surface and the front surface of the first compression device; compressing a breast between the first and second compression devices, the radiolucent comfort element providing comfort; and obtaining a mammogram of the compressed breast, the radiolucent comfort element producing no significant visual artifact on the mammogram. 16

27. The method of claim 26, further comprising removing the radiolucent comfort element from the first compression device after obtaining the mammogram.

28. The method of any one of claims 23 to27, wherein the radiolucent comfort element comprises an opening therethrough, the method further comprising accessing the breast through the opening in the compression plate.

29. The method of claim 28, wherein the breast is accessed through the opening to perform a biopsy of tissue of the breast.

30. The method of claim 29, wherein the breast is accessed through the opening to place a device to identify a specific location in the breast.

31. The method of claim 29, wherein the opening through the radiolucent comfort element comprises a window.

32. The method of claim 23, wherein the radiolucent comfort element is releasably attached to the compression surface, and wherein the method further comprises removing the radiolucent comfort element from the compression plate.

33. The device of claim 1, wherein the radiolucent comfort element comprises a radiolucent pad comprising first and second surfaces and having a thickness between 0.050 (1.27 mm) and 0.500 inch (12.7 mm); and an adhesive layer on the second surface for releasably attaching the pad to the compression surface. Dated 5 November, 2009 BioLucent, LLC Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON