Abstract:
A patient support includes an upper support plate which is provided with a headrest. A base plate is arranged below, and separate from the upper support plate, by a floating mounting. A single narrow, narrow support column is provided, in the region of the headrest, between the support plate and the base plate. An upper face of the support plate consists of a forward zone, a mid-zone and an end zone. A width of the support plate reduces continuously from a widest point in the forward zone to a narrow space in the mid-zone and then widens continuously to the end of the support plate. Left and right sections of the patent support are formed and run horizontally arranged symmetrically about a longitudinal and symmetrical axis of the support plate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the U.S. national phase, under 35 USC 371, of PCT/DE2006/000456, filed Mar. 16, 2006; published as WO 2006/099841 A1 on Sep. 28, 2006 and claiming priority to DE 10 2005 013 151.4, filed Mar. 22, 2005, the disclosures of which are expressly incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The subject invention is directed to a patient support. The patient support includes an upper support plate and a base plate which is spaced from, and beneath the upper support plate. 
       BACKGROUND OF THE INVENTION 
       [0003]    Patient supports, which may be equipped with a breast immobilizing device, a biopsy device or a marking device, are generally known in the art. Such patient supports have two openings in an upper support plate, into which openings the patient&#39;s breasts can be placed, freely hanging, for examination. The upper support plate is supported against a lower base plate, which is spaced several centimeters from it, typically via multiple, such as, for example, four support pillars. 
         [0004]    DE 196 26 286 C2 shows an MRI breast coil with a device for immobilizing a breast for biopsy. This device comprises a patient support with an upper support plate having two openings and also having breast pressing elements, spaced from one another. A breast is placed in a space between these pressing elements, and the breast is ultimately immobilized by bringing the pressing elements together, after which immobilization, the breast can be biopsied, for example. 
       SUMMARY OF THE INVENTION 
       [0005]    The object of the present invention is to provide a patient support configured with an upper support plate and with a base plate spaced horizontally from the upper support plate, in which space, an access area to provide the accessibility to the breast(s), which are suspended in the space between the support plate and the base plate, is significantly expanded for diagnostic and/or interventional measures, and in which space, breast immobilizing apparatus can be used. 
         [0006]    This object is attained by the provision of a patient support having an upper support plate and a base plate which is arranged beneath, and spaced from the support plate. The support plate has a cantilevered portion with a head support surface. A single, weight-bearing, narrow support pillar supports the upper support plate and spaces it from the base plate. 
         [0007]    The advantages of the present invention consist especially in that the patient support of the present invention can accommodate a device for immobilizing a breast, with or without a device for biopsying or marking a defect in the tissue structure inside the breast. A very large slewing angle range around a vertical or perpendicular pivoting axis is provided for the aforementioned device. In a forward portion of an intermediate space between the support plate on the top and the base plate on the bottom, as viewed in the direction of the support plate&#39;s longitudinal axis, and from the area of an opening or a recess for the breast, up to the start or the headrest area of the head support surface of the support plate, one or more narrow and short support elements is/are provided. These or this support elements or element are crossing through the intermediate space in a horizontal and a vertical direction, and serve to support the support plate. The upper support plate can still be advantageously extended far enough lengthwise that the head, or at least the upper body of the patient resting on the patient support, can be supported, or can rest directly or indirectly on the upper support plate. In this manner, the need for additional headrests outside of, or in front of the patient support, which would impede access to the immobilized breast in the direction of the head/feet, is advantageously eliminated. A further advantage of the present invention is that the patient support can be used, for example, in computer tomography (CT), magnetic resonance imaging (MRI) or positron emission tomography (PET). The patient support, in accordance with the present invention permits, in an inventive manner, the arrangement of one or more receiving surface coils without significantly decreasing the rotational range of an immobilization and/or a biopsy device to be used. The receiving surface coils can be mounted, oriented horizontally, in or on the base plate. Horizontally oriented receiving surface coils can also be mounted directly or indirectly on the support plate, and can also be horizontally and/or vertically displaceable, for example. 
         [0008]    A device for immobilizing a breast, with or without a holder for a medical tool, such as a biopsy or a marking tool can be easily inserted into and removed from the patient support. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    A preferred embodiment of the present invention is represented in the set of drawings and will be described in greater detail in what follows. 
           [0010]    The drawings show in: 
           [0011]      FIG. 1 , a top plan view of the patient support in accordance with the present invention, with a view of a, for example, rectangular mounting recess in the base plate for a mounting plate for a device for immobilizing a breast, with or without a holder for a medical tool, such as a biopsy or a marking tool for a breast and/or for one or more horizontally oriented MRI receiving surface coils 
           [0012]      FIG. 2 , a top plan view in accordance with  FIG. 1 , and with a mounting plate installed in the mounting recess 
           [0013]      FIG. 3 , a front perspective view of the patient support of  FIG. 1 , with a view of the front support surface in accordance with the present invention with a cantilevered head section with a head support surface, which transitions in the direction of the patient&#39;s feet into a narrow bridge, and ultimately is attached, at the end of the support plate, via its upper body support section, to the end plate, which extends in a vertical and a horizontal direction 
           [0014]      FIG. 4 , a perspective end view of an end plate of the patient support, which connects the ends of the support plate and the base plate and extends in a vertical direction 
           [0015]      FIG. 5 , a plan view of the upper side of the mounting plate with two conical mounting holes, each equipped with internal teeth; in 
           [0016]      FIG. 6 , a view of the underside of the mounting plate according to  FIG. 5 , with one annular groove incorporated into each mounting hole, concentrically thereto, in the underside of the mounting plate, and configured to accommodate a receiving surface coil 
           [0017]      FIG. 7 , a right side view of the patient support of the present invention, with a patient lying with the front side of her upper body resting on the support plate and also with a device for immobilizing a breast, which is oriented, non-rotatably, parallel to the longitudinal axis of the support plate, with two immobilization grids that can be moved toward one another in an adjustable spacing, and with a device for biopsying or marking a defect in the tissue structure inside the breast 
           [0018]      FIG. 8 , a view, between the underside of the head section of the head support plate and the upper surface of the base plate, of a device for immobilizing a breast with a device for biopsying or marking the breast, a vertical plane of that immobilizing device, that extends along its longitudinal axis, intersecting a vertical plane that extends along the longitudinal and symmetrical axis of the support plate in an adjustable angle of intersection 
           [0019]      FIGS. 9 and 10  patient supports in accordance with the prior art. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    Computer tomography (CT) is a diagnostic procedure in which the region of a human body to be examined is irradiated by a focused x-ray bundle via an x-ray tube rotating around the body. 
         [0021]    In magnetic resonance imaging (MRI), images of the human body are generated without the use of ionizing radiation, or in other words, without the use of x-rays or radioactive materials. 
         [0022]    Positron emission tomography (PET) is a highly sensitive procedure with which metabolic processes in the body can be visualized. 
         [0023]    With CT, MRI, and PET examination, the location of an anomaly in an immobilized breast can be precisely measured within an orthogonal system of coordinates. These location defining values can be manually or automatically preset in a medical tool, such as a biopsy needle, outside or inside the MRI coil, on a tool holder that can be adjusted horizontally and vertically using dials. The preset medical tool holder can be easily inserted into the patient support. 
         [0024]    Referring initially to  FIG. 1 , patient support  1 , in accordance with the present invention, is comprised of a base plate  2  that extends in a horizontal direction, and a support plate  3 , which is arranged above the base plate  2  at a spacing h and extending in a horizontal direction. Between these two plates  2  and  3 , an intermediate space  14  is provided. The spacing h, such as, for example, of 80-100 mm between an underside  27  of support plate  3  and an upper side  29  of the base plate  2  need not be equal over the entire length of the patient support  1 . A longitudinal axis of symmetry  20  divides the outer surface of the support plate  3  into a left surface part and a right surface part. All the components of the patient support  1  are made of an MR-appropriate material, such as, for example, plastic or the like. 
         [0025]    The support plate  3  is comprised essentially of three main zones along its longitudinal axis  20 , starting at the head end 
         [0026]    A front zone ZF with a head support surface  4  of a head section  5 . This front zone extends, for example, over approx. 35% of the length of the support plate  3 . The front zone ZF serves as the support surface for the head and the shoulder area of a patient, as seen in  FIG. 7 . Under the front zone ZF of the upper support plate  3 , or in other words in the front part of the intermediate space  14 , one or more narrow support elements or support pillars  23 , which are short relative to the overall length of the patient support, is/are preferably provided along or spaced laterally from a vertical plane that spans the longitudinal and symmetrical axis  20  in a perpendicular orientation. The support element or elements  23  is orare adhesively or positively connected to the underside of the upper support plate  3  and to the upper side of the base plate  2 . In the preferred embodiment, the upper and/or lower part of the support element, or elements  23  is orare configured as pressure distribution plates, which are adhesively or positively connected to the underside of the support plate  3  and/or to the upper side of the base plate  2 . For this reason, the upper and lower ends of each of the support element or elements  23  is or are widened into a mushroom shape. 
         [0027]    The support element or elements  23  is orare arranged at a slight distance, such as, for example, at 70 to 150 mm, from the forward edge of the head support plate  3 . If only a single support element  23  is used, it is, for example, 10 to 150 mm wide and is, for example, 10 to 200 mm long at its narrowest point. 
         [0028]    The position of the support element, or elements  23  and the height h of the intermediate space  14  are configured such that a device for immobilizing a breast, with or without a holder for a medical tool, such as a biopsy or a marking tool  22 , hereinafter abbreviated to device  22  can be rotated approximately 360° in each of its working positions, preferably around a perpendicular axis at the respective instantaneous center of rotation of the horizontally aligned receiving surface coil. The rotational motion of the device  22  therefore is not impeded by obstructions. 
         [0029]    With the advantageous positioning of the support element or elements  23 , the upper support plate  3  of the patient support  1  can advantageously be extended in a patient cranial direction far enough so that the head of the patient, who is lying with at least her upper body on the support plate  3 , again as seen in  FIG. 7 , can be supported or rested directly or indirectly on the patient support  1 . This advantageously eliminates the need for a patient support which would be arranged outside of, such as, for example, in front of the patient support. Such a support would make access to an immobilized left breast  24  or right breast  26 , viewed in the head-foot direction, impossible in the caudal or head-foot direction. In this regard note the prior art which is represented in  FIGS. 10 and 11 . 
         [0030]    A center zone ZC, also referred to as the “chest zone,” is adjacent to the front zone ZF of the patient support  1  in the caudal direction of the support plate  3 . This center zone ZC extends, for example, over approx. 50% of the length of the support plate  3 . It has the form of, for example, a bridge  30  that narrows for half of its length and then widens again. This center zone surface supports the patient&#39;s sternum. To the left and to the right of the longitudinal and symmetrical axis  20  of the bridge  30 , the bridge  30  widens to define a left cut-out  33  and, opposite that, to the right of the longitudinal and symmetrical axis  20 , a right cut-out  32 . The left cut-out  33  is open to the outside on the left of the bridge  30 , the right cut-out  32  is open to the outside on the right of the bridge  30 , as seen in  FIG. 1 . The bridge  30  can be between 40 mm and 100 mm wide, for example, at its narrowest point. The contours of the cut-outs  32  and  33  can each take the shape of a horizontal parabola, in a horizontal plane or in a plane that is inclined upward or downward in relation to that horizontal plane. Their vertices can be spaced at equal or unequal distances from the longitudinal and symmetrical axis  20 , although equal spacing is preferable. These cut-outs  32  and  33 , which open wide toward the outside of the support plate  3 , enable even larger breasts to hang through the respective cut-outs freely and very deeply, before being immobilized. Furthermore, they permit an expanded, unobstructed view of the device  22  with the immobilized breast  24  and/or  26 . 
         [0031]    This is particularly important because the device for immobilizing a breast with the device  22  can be rotated or turned around its vertical axis up to 360°, continuously or in small steps, before the breast is immobilized, and can then be detachably secured against torsion. 
         [0032]    The end zone ZE or the end surface of the support plate  3  extends to the rear of the bridge  30 . Beginning at the end of the support plate bridge  30 , it extends over approx. 15% of the length of the support plate  3 . It serves as the support surface  6  for the upper part of the user&#39;s abdomen, adjacent to the chest—as viewed in the direction of the feet. In this regard, see  FIGS. 1 and 7 . 
         [0033]    The support surface  6  of the end zone ZE of the support plate  3  ends at the end plate  9 , which end plate  9  extends both vertically and horizontally. The end of the support plate  3  is preferably adhesively or positively connected to an upper part  7  of the end plate  9 . A lower part  10  of the end plate  9  is adhesively or positively connected to the end of the base plate  2 . 
         [0034]    With the elevated projection of the left cut-out  33  and of the right cut-out  32  in the intermediate space  14 , an imaginary left planar section  39  and an imaginary right planar section  40 , respectively, are formed on the upper side  29  of the base plate  2 . The device for immobilizing a breast  22 , with or without a holder for a medical tool or a biopsy, or marking tool is arranged in the left  49  and/or the right working space  50  bounded in this fashion. 
         [0035]    Therefore, the area below the cut-outs  32 ,  33  and consisting of the left  49  andor the right working space  50  and the bridge  30  is the area in which the device  22  is arranged. As described above, device  22  can be rotated 360° around a vertical axis. 
         [0036]    The slewing or rotational motion of the device  22  is advantageously not impeded or restricted by obstructions. 
         [0037]    A rectangular mounting plate  11 , as seen in  FIG. 5 , the length of which corresponds nearly to the entire width of the base plate  2  in the area of the bridge  30  of the support plate  3 , is removable, and is mounted, in a positive manner, in a mounting recess  8  or in a mounting hole  8 , such as by, for example, a guide, such as a flat or dovetailed guide. The mounting recess  8  or mounting hole  8  is integrated into the base plate  2 , and is open to its upper side. The mounting plate  11  has, for example, two circular, continuous mounting holes  12 ;  16 , which are preferably equal in diameter. The centers of the two mounting holes  12 ;  16  and therefore the centers of the receiving surface coils  37 ,  38  have unequal spacings a and b, with a difference, for example, of 3 to 4 cm, from the transverse center line  34  of the mounting plate  11 . The reason for this difference in the spacings a and b is the advantageous capability of adjusting to different upper body widths and/or breast spacing in the patients being examined. 
         [0038]    The mounting holes  12 ;  16  in the mounting plate  11  are each equipped, for example, with internal toothing  13 ;  17 . The underside  15  of the mounting plate  11 , which is shown in  FIG. 6  is provided with an annular left groove  21 , which is configured to accommodate a left receiving surface coil  38 , and an annular right groove  19 , which is configured to accommodate a right receiving surface coil  37 , each groove  19 ,  21  being integrated concentrically in relation to its respective mounting hole  12 ;  17  in the underside  15  of the mounting plate  11 . 
         [0039]    So that the device  22 , without the immobilized breast can be rotated or can be turned up to 360° on its vertical axis, either continuously or in small steps, and can then be detachably secured against torsion, a collar, for example in the form of a circular ring, for example with an exterior cone, is applied, for example, to the underside of the base plate  2  of the device  22 , in an adhesive or positive connection. The circular ring is equipped, for example, with a ring gear having a conical exterior. The collar can be placed in positive connection with a receptacle configured to fit it. The collar and the receptacle thus form a coupling. This coupling can be configured, for example, as a switchable and optionally as a detachable positive coupling or as a non-positive coupling. In the preferred embodiment, a switchable, positive coupling, such as a toothed coupling, is used. 
         [0040]    The teeth of the externally conical toothed ring or collar can be respectively placed in and taken out of engagement, i.e. coupled and decoupled, with the internal toothing  13 ;  17  of the, for example, two conical mounting holes  12 ;  16  or mounts of a mounting plate  11  for the device  22 . They thus form a switchable, and preferably on optionally detachable, positive coupling. 
         [0041]    To couple and decouple, and to rotate the device  22  around its vertical axis, the device is first raised, thereby detaching its conical external toothing from the allocated internal toothing  13 ;  17  of the first mounting hole  12  and/or the second mounting hole  16 , after which the device  22  is turned or rotated a selectable angle around its vertical axis, and is then placed back in engagement. As described above, the applicable coupling mode is not limited to the toothed coupling principle. Other positive coupling methods, and non-positive couplings, such as cone friction couplings, could also be used. 
         [0042]    The mounting plate  11  with the two mounting holes  12 ,  16  can also be shorter in structure, so that it can be displaced crosswise to the longitudinal axis  20 , guided by a suitable guide, and then can be locked in place in a desired position via a locking device that operates in a non-positive or in a positive fashion. To save on overall height, the mounting plate  11  can be displaced in the mounting recess  8  or the mounting hole  8 . 
         [0043]    The mounting plate  11  can also be provided with only with one mounting hole  12  for only one MRI receiving surface coil  38 . In that case, only one MRI receiving surface coil  38  would be necessary, which would be used to examine both the left breast and the right breast. The accordingly short mounting plate would then need only to be shifted from the left side to the right side, crosswise to the direction of the longitudinal axis  20 , via a guide. 
         [0044]    In addition to the lower left receiving surface coil  38 , which extends horizontally, and/or the lower right receiving surface coil  37 , which extends horizontally, in the base plate  2  and/or in the mounting plate  11 , an additional upper left  47  or upper right receiving surface coil  48  that extends horizontally can be provided, in order to improve image quality. These coils, which are also referred to as upper receiving surface coils, are attached directly or indirectly to the support plate  3 , such as, for example, to a cushion on the patient support  1 . The upper left and lower left receiving surface coils form a breast coil pair oriented horizontally on the left. The upper right and the lower right receiving surface coils form a breast coil pair that is oriented horizontally on the right. The centers of the left and right breast coil pairs should lie at a common left perpendicular and at a common right perpendicular, respectively. The upper receiving surface coils are made of metal and are insulated against electrical current and heat. They have the shape, for example, of a circular ring that is separated at some point through its entire ring width, giving the circular ring two connecting ends. The upper receiving surface coils are rigid in structure. They are preferably fastened to the bridge  30  at the area of their connecting ends, and are electrically connected. The upper receiving surface coils project outward from the bridge  30  to the left or right into the left cut-out  32  or into the right cut-out  33 , respectively, oriented horizontally. 
         [0045]    The device for immobilizing a breast, with or without a holder for a medical tool, such as a biopsy device or a marking tool  22  can have two vertically oriented receiving surface coils, specifically a left and a right receiving surface coil, spaced from one another. The vertical receiving surface coils are preferably attached to the two immobilizing grids. 
         [0046]    In this case, the upper horizontal receiving surface coil, the right vertical receiving surface coil, the lower horizontal receiving surface coil, and the left vertical receiving surface coil together form a coil array. 
         [0047]    In what now follows, the subject of the application will be summarized again: 
         [0048]    The patient support  1  in accordance with the present invention is comprised of an upper support plate  3  and a base plate  2 , which base plate  2  is arranged beneath and is spaced somewhat from the upper support plate  3 . The two are separated from one another by an intermediate space  14 . The upper support plate  3  has, in its front zone ZF, a cantilevered part with a head support surface  4 . In the area of the head support surface  4  of the support plate  3 , between its underside  27  and an upper side  29  of the base plate  2 , the load bearing, narrow support pillar  23  is provided. It is connected in a positive or adhesive fashion to the upper side  29  of the base plate  2  and to the underside  27  of the support plate  3 . 
         [0049]    Viewed crosswise to the longitudinal axis  20  of the support plate  3 , the support pillar  23  is narrow, for example, is 1 cm to 15 cm wide, as compared with the width of the support plate  3  and viewed in the direction of the longitudinal axis  20 , is short in relation to the length of the support plate  3 , such as, for example, is 1 cm to 20 cm long. 
         [0050]    The end  25  of the base plate  2  is adhesively or is positively connected to the end  18  of the support plate  3  by the provision of an end plate  9  that extends vertically and horizontally. 
         [0051]    The directions of the longitudinal axes of the support pillars  23  of the support plate  3  can extend in any opening angle in relation to one another, however, such an angle is preferably equal to zero degrees or to a few degrees, for example up to plus/minus 10°. 
         [0052]    It is especially beneficial when the vertical plane along the longitudinal axis of the support pillar  23  and the vertical plane along the longitudinal axis  20  of the support plate  3  coincide. 
         [0053]    The vertical plane along the longitudinal axis of the support pillar  23  and the vertical plane along the longitudinal axis  20  of the support plate  3  can, however, also be spaced horizontally from one another. 
         [0054]    The upper support plate surface width  31  of the support plate surface  6  of the support plate  3  has at least three successive surface zones, starting at its forward edge and continuing to its trailing end  18 : a front zone ZF, a center zone ZC that follows the first front zone ZF, and an end zone ZE that follows the center zone ZC. 
         [0055]    Viewed in the direction of the end  18  of the support plate  3  or in the direction of the patient&#39;s feet, the width  31  of the support plate surface  6  of the support plate  3  decreases continuously from its widest point in the front zone ZF to a narrow intermediate piece  30  in the center zone ZC. From there, it widens again continuously up to the end of the support plate  3  in the end zone ZE. Thus, the left cut-out  33  and the right cut-out  32  are formed. The left cut-out  33  and the right cut-out  32  extend in a horizontal direction, preferably they are arranged horizontally, and they are symmetrical to the longitudinal and symmetrical axis  20 . 
         [0056]    The width  31  of the support plate surface  6  can decrease according to the principles of a plane curve. 
         [0057]    The plane curve can be a straight line or a parabola or a circle or an ellipse or a hyperbola. 
         [0058]    The plane curve can optionally be comprised of parts of a straight line and/or a parabola and/or a circle and/or an ellipse and/or a hyperbola. 
         [0059]    In the intermediate space  14 , with the left planar section  39  and the right planar section  40 , formed on the upper side  29  of the base plate  2  by the elevated projection of the left cut-out  33  and the right cut-out  32 , respectively, a left working space  49  and a right working space  50 , respectively, are formed. In the working space  49  and/or  50 , the device for immobilizing a breast  22  is arranged. The device for immobilizing a breast  22  is supported, either directly or indirectly, on the base plate  2  and is directly or indirectly connected to it, positively or adhesively. 
         [0060]    In the left working space  49  and/or in the right working space  50 , in addition to the device for immobilizing a breast  22 , a holding device  41  for a medical tool can also be arranged. The holding device  41  for the medical tool is supported directly or indirectly on the base plate  2 . The holding device  41  can be positively or adhesively connected to the device for immobilizing a breast  22 . 
         [0061]    The device for immobilizing a breast  22  can be arranged within the left working space  49  and/or within the right working space  50 , so as to be capable of rotating around a vertical axis  42 ,  43  and locked in place. 
         [0062]    In the left working space  49  and/or in the right working space  50 , at least one left and/or one right, horizontally oriented MRI-capable receiving surface coil  37 ,  38  can be arranged. 
         [0063]    In the left working space  49  and/or in the right working space  50 , inside of, or on or under the base plate  2  a mounting device  11 , which is configured to hold at least one MRI-capable receiving surface coil  37 ,  38 , can be arranged. 
         [0064]    The mounting device  11  can be displaceable horizontally, crosswise to the longitudinal and symmetrical axis  20 . 
         [0065]    The mounting device  11  can have one or two devices  12 ,  13  for holding a device for immobilizing a breast  22 , either with or without a holding device  41  for a medical tool. 
         [0066]    The device for immobilizing a breast  22 , with or without a holding device  41 , can be connected directly or indirectly to the base plate  2  via an optionally detachable and lockable non-positive or positive coupling  12 ,  13 . 
         [0067]    In the left working space  49  and/or in the right working space  50 , two MRI-capable receiving surface coils  44 ,  45 , spaced from one another and parallel to one another, can be arranged, oriented vertically. One or both of the vertically oriented, MRI-capable receiving surface coils  41 ,  45 , spaced from one another, can be secured to the device for immobilizing a breast  22 . 
         [0068]    However, one or both of these vertically oriented, MRI-capable receiving surface coils  41 ,  45 , which are spaced apart from one another, could also be attached to the inner surface  46  of the end plate ( 9 ). 
         [0069]    The patient support can have an upper left  47  and/or an upper right MRI-capable receiving surface coil  48 , which operate in the left working space  49  and/or the right working space  50 , respectively. The upper left  47  and/or the upper right  48  MRI-capable receiving surface coil can be attached directly or indirectly on the support plate  3 . 
         [0070]    While preferred embodiments of a patient support, in accordance with the present invention, have been set forth fully and completely hereinabove, it will be apparent to one of skill in the art that various changes in, for example, the specific material used to form the patient support, the overall size of the support, and the like could be made without departing from the true spirit and scope of the present invention which is accordingly to be limited only by the appended claims.