Abstract:
A cryosurgical device and system is provided comprising a pressurized container, a metered valve that regulates the retrieval of a coolant solution stored in the pressurized container and regulates the volume of coolant solution dispensed with each actuation of the device, an actuator that engages the metered valve when engaged, and directs the coolant solution to an extension tube, which directs the coolant solution away from the pressurized container, and an applicator head configuring an open-ended enclosure attached to a distal end of the extension tube.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to the field of cryosurgical devices for cryosurgically treating skin diseases and more particularly to a cryosurgical device for applying a cryogenic refrigerant from a pressurized container in metered doses. 
     BACKGROUND OF THE INVENTION 
     Cryosurgery is the application of extreme cold to destroy abnormal or diseased tissue and can be used to treat a number of skin diseases and disorders. Cryosurgery is generally employed in the medical field for the removal of skin lesions from the body of a mammal, including the human body. When extreme cold is applied to abnormal cells, ice crystals can form inside the cells, which can rupture their cell membranes, thus destroying the cells. The extreme cold can also freeze blood vessels supplying blood to the abnormal cells. 
     Traditionally, liquid nitrogen has been used as the coolant solution in cryosurgery. However, other coolant solutions have been used and are known by those of skill in the art. Historically, the coolant solution was applied to the abnormal tissue with a cotton or foam swab. 
     More recently, however, methods were developed to spray the coolant solution onto the abnormal tissue. In these methods, the coolant solution is typically stored in a pressurized container, and, upon demand, an uncontrolled amount of coolant solution is dispensed from the container into a supply tube. In some methods, the coolant solution can exit the supply tube and be dispersed into a cone, cup, or speculum placed around the abnormal tissue to pool the solution. In other methods, the supply tube can have a porous tip applicator, for example a cotton or plastic foam applicator, located at the distal end of the tube. The coolant solution can accumulate in the applicator, and the applicator can be applied to the surface of the abnormal tissue. 
     When coolant solution is applied to a treatment area, the coolant solution must remain in contact with the treatment area for a period of time until what is called an ice ball, by those of ordinary skill in the art, is formed. The ice ball must be maintained for approximately 30 seconds and should be big enough to cover the treatment area, which includes the abnormal tissue as well as an area 1-2 mm around the abnormal tissue in all directions. 
     After the ice ball is formed, it is maintained for a sufficient period of time. During this time, the coolant solution vaporizes and evaporates. Part of the evaporation process is called bubbling by those of ordinary skill in the art, and it is desirable for a practitioner to be able to view bubbles during the bubbling process. As the bubbles begin to dissipate, a thawing process can begin. If a practitioner wishes to maintain the ice ball for a longer period of time, more coolant solution should be applied to the treatment area when the bubbles begin to dissipate. 
     Typically an ice ball will need to thaw for approximately one minute. Most destruction of the abnormal cells in the treatment area occurs during the thawing phase. The freeze and thaw cycle described above can be repeated as necessary depending on the size of the treatment area. 
     Devices used in connection with the above-described methods known by those of skill in the art incorporate several disadvantages. First, the coolant solution is often wasted. 
     When an uncontrolled amount of coolant solution is dispensed from the container, a large portion of the coolant solution is wasted due to the uncontrolled dispensing from the container and what is called blowback by those of skill in the art. When this happens, an excessive amount of coolant solution is released into the surrounding atmosphere rather than directed onto the abnormal tissue. 
     When a cone is used by a practitioner in connection with applying coolant solution to a treatment area, both hands are often required for application. As such, often a second person is required to assist when treating difficult to reach areas. 
     When a porous tip applicator is used to apply the coolant solution to abnormal tissue, an excessive amount of coolant solution is often delivered through the supply tube to saturate the applicator. When this happens, coolant solution is dispensed directly into the atmosphere and thus, coolant solution is wasted. Furthermore, not all of the coolant solution absorbed in or on the applicator reaches the abnormal tissue. A portion of the coolant solution remains in or on the applicator when applied to the treatment area. Additionally, the shapes of these applicators do not allow the coolant solution to be distributed evenly or onto a precisely demarcated area. 
     Another disadvantage of devices used in connection with the above-described methods is that the coolant solution is dispersed in an uncontrolled manner. Thus, coolant solution is often sprayed or splashed outside of the intended treatment area onto the patient&#39;s body or a practitioner&#39;s hands or arm. 
     There is thus a continuing, ongoing need for a cryosurgical device for cryosurgically treating skin lesions that provides for effective treatment of the abnormal tissue, that does not waste the coolant solution used in connection with the device, and that evenly distributes a controlled amount of coolant solution to a well defined area. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a benefit of the present invention to provide a cryosurgical device and system for cryosurgically treating skin disease and a method of using such a device and system that provides for the effective treatment of abnormal tissue. 
     It is further benefit of the present invention to provide a cryosurgical device and system for cryosurgically treating skin disease and a method of using such a device and system that does not waste the coolant solution used in connection with the device. 
     It is another benefit of the present invention to provide a cryosurgical device and system for cryosurgically treating skin disease and a method of using such a device and system to evenly distribute a controlled amount of coolant solution to a precisely demarcated area and to prevent spraying or splashing of the coolant solution onto undesired areas of the patient or practitioner. 
     It is still another benefit of the present invention to provide a cryosurgical device and system for cryosurgically treating skin disease and a method of using such a device and system that incorporates a metered valve for delivering a coolant solution to the abnormal tissue. 
     It is another benefit of the present invention to provide a cryosurgical device and system for cryosurgically treating skin diseases and a method of using such a device and system that facilitates a practitioner applying coolant solution to a treatment area to generate an ice ball, maintaining the ice ball for a sufficient period of time, observing bubbling, and actuating the device additional times as necessary to apply more coolant solution to maintain the ice ball for the necessary time period before thawing begins. 
     It is still another benefit of the present invention to provide a cryosurgical device and system for cryosurgically treating skin diseases and a method of using such a device and system that facilitates multiple freeze and thaw cycles occurring. 
     It is yet another benefit of the present invention to provide a cryosurgical device and system for cryosurgically treating skin disease and a method of using such a device and system that controls the duration of freezing the abnormal tissue to which the coolant solution is applied. 
     It is a further benefit of the present invention to provide a cryosurgical device and system for cryosurgically treating skin disease and a method of using such a device that allows for single handed operation of the device and system by a practitioner. 
     Finally, it is a benefit of the present invention to provide a method of using a cryosurgical device and system for cryosurgically treating skin disease and a method of using such a device and system that allows a user to effectively view and assess a treatment area while a coolant solution is being administered to the area. 
     In accordance with the present invention, all of these benefits as well as others not herein specifically identified, are generally achieved by the present cryosurgical device with a metered dose. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various examples of benefits, features and attendant advantages of the present invention will become fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, wherein: 
         FIG. 1  illustrates a perspective view of a cryosurgical device in accordance with one embodiment of the present invention; 
         FIG. 2  illustrates a cross-sectional view of a first applicator head in accordance with a first embodiment of the present invention; 
         FIG. 3  illustrates a perspective view of a second applicator head in accordance with the first embodiment of the present invention; 
         FIG. 4   a  illustrates a first cross-sectional view of an applicator head in accordance with the first embodiment of the present invention; 
         FIG. 4   b  illustrates a second cross-sectional view of an applicator head in accordance with the first embodiment of the present invention; 
         FIG. 4   c  illustrates a third cross-sectional view of an applicator head in accordance with the first embodiment of the present invention; 
         FIG. 4   d  illustrates a fourth cross-sectional view of an applicator head in accordance with the first embodiment of the present invention; 
         FIG. 5  illustrates a fourth cross sectional view of an applicator head in accordance with the first embodiment of the present invention; 
         FIG. 6   a  illustrates a first end view of an applicator head in accordance with the present invention; 
         FIG. 6   b  illustrates a first bottom opening view of an applicator head in accordance with the present invention; 
         FIG. 7   a  illustrates a second end view of an applicator head in accordance with the present invention; 
         FIG. 7   b  illustrates a second bottom opening view of an applicator head in accordance with the present invention; 
         FIG. 8   a  illustrates a third end view of an applicator head in accordance with the present invention; 
         FIG. 8   b  illustrates a third bottom opening view of an applicator head in accordance with the present invention; 
         FIG. 9   a  illustrates a fourth end view of an applicator head in accordance with the present invention; 
         FIG. 9   b  illustrates a fourth bottom opening view of an applicator head in accordance with the present invention; 
         FIG. 10  illustrates a cross-sectional view of a cryosurgical device in accordance with a second embodiment of the present invention; 
         FIG. 11  illustrates a perspective view of an applicator head in accordance with a second embodiment of the present invention; 
         FIG. 12  illustrates a side view of an applicator head in accordance with the second embodiment of the present invention; 
         FIG. 13  illustrates an end view of an applicator head in accordance with the second embodiment of the present invention; 
         FIG. 13   a  illustrates a cross-sectional view of line A-A of an applicator head in accordance with the second embodiment of the present invention; 
         FIG. 13   b  illustrates a cross-sectional view of line B-B of an applicator head in accordance with the second embodiment of the present invention; and 
         FIG. 13   c  illustrates a detailed view of a stop located in an applicator head in accordance with the second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While this invention is susceptible of an embodiment in many different forms, there are shown in the drawings and will be described herein in detail specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention. It is not intended to limit the specific illustrated embodiments. 
     Embodiments of the claimed invention include a cryosurgical device and system for cryosurgically treating skin lesions that provides for effective treatment of the abnormal tissue, that does not waste the coolant solution used in connection with the device, and that evenly distributes a controlled amount of coolant solution to a well defined area. 
       FIG. 1  illustrates a perspective view of a cryosurgical device  10  for use in a system in accordance with a first embodiment of the present invention. As seen in  FIG. 10 , the cryosurgical device  10  can incorporate a container  12 . The container  12  can be made of, for example, steel or aluminum, and can be used to safely hold a coolant solution, for example, a liquid cryogen. In embodiments of the claimed invention, the container  12  can be pressurized and can be, for example, an aerosol container. 
     The container  12  can contain a coolant solution that can be used in connection with cryosurgically treating skin diseases, for example, skin lesions. The coolant solution can be, for example, liquid nitrogen, or any solution known by those of skill in the art to be used in cryosurgery. In embodiments of the claimed invention, the coolant solution can be a mixture of 95% dimethyl ether (DME) and 5% propane or a mixture of 95% DME, 2% propane, and 3% isobutene. In alternate embodiments, the coolant solution can be R-404a, which is a mixture of 52% 1,1,1-trifluoroethane, 44% pentafluoroethane, and 4% 1,1,1,2-tetrafluoroethane. It is preferred that the coolant solution has a boiling point below −20° F. 
     A system in accordance with the present invention comprises a cryosurgical device  10  that can incorporate a cup  14  housing a metered valve, as known by those of ordinary skill in the art, a valve stem  15 , and an actuator  16 . The cup  14  housing the metered valve  15  can seal the container  12 , and the metered valve  15  can function in connection with the container  12  and the actuator  16 . An extension tube  18  can extend from the actuator  16  away from the device  10 , and an applicator head  20  can be located at a distal end of the extension tube  18 . 
     In alternate embodiments of the claimed invention, a cryosurgical device can incorporate a cup housing a metered valve, an actuator, and an extension tube. A coolant solution can be dispersed from the container through the metered valve, the actuator, and extension tube. The coolant solution can exit a distal end of the extension tube and be applied to a treatment area with the use of, for example, a cone as is known by those of ordinary skill in the art. 
     Referring to  FIG. 10 , a cross-sectional view of a cryosurgical device in accordance with a second embodiment of the present invention is shown. Elements of the cryosurgical device  10 ′ are most clearly illustrated in  FIG. 10  and are described in further detail. 
     A metered valve assembly  100  can be incorporated into the device. The metered valve assembly  100  includes a valve cup  14 ′, which seals the container and holds the metered valve. A dip tube  17  extends from the metered valve assembly  100  into the container  12 ′ and directs the coolant solution  19  from the container  12 ′ to the metered valve in the valve cup  14 ′. 
     When the actuator/trigger assembly  16 ′ is at rest, a chamber in the metered valve fills up thereby measuring a predetermined amount of coolant solution  19 . When the actuator/trigger assembly  16 ′ is engaged, the coolant solution  19  is released from the chamber of the metered valve through the valve stem  15 ′, through the actuator/trigger assembly  16 ′, and into the applicator tube  18 ′ thus delivering one dose of the predetermined amount of coolant solution  19  to the applicator head  20 ′. Different metered valves can measure different predetermined amounts of a coolant solution. 
     One actuation of the predetermined amount of coolant solution measured by the metered valve provides a single dose of the coolant solution. Accordingly, the metered valve to be used can be determined based upon the size of the abnormal tissue to be treated. That is, when a larger area is to be treated, a metered valve can be used that measures a larger predetermined amount of coolant solution. Similarly, when a smaller area is to be treated, a metered valve can be used that measures a smaller predetermined amount of coolant solution. 
     Alternatively, a metered valve that delivers a fixed volume of coolant solution can be used, and a practitioner can simply apply the coolant solution in multiple actuations as necessary to treat the treatment area. The delivery of the fixed amount of coolant solution can be repeated a defined number of times based on the size and area of the treatment area. For example, when the size and area of the treatment area are large enough to require more than the fixed amount of coolant solution delivered with one engagement of the actuator, the actuator can be engaged repeatedly until the desired amount of coolant solution has been delivered. A user will know the size and area of the treatment area prior to using the device. Accordingly, a user can calculate how much of the coolant solution is necessary to treat the treatment area. A user will also know the fixed amount of coolant solution that is delivered from the container with one engagement of the actuator. Accordingly, a user can calculate how many times he or she must engage the actuator to deliver the required amount of coolant solution for the particular treatment area being treated. In embodiments of the claimed invention, the metered valve can deliver from approximately 10 microliters with each engagement of the actuator up to a volume as large as would be known by those or ordinary skill in the art. 
     A practitioner observing an ice ball formed over the treatment area, can apply the coolant solution as necessary in multiple actuations as bubbling begins to dissipate. In this manner, the ice ball can be maintained for a longer period of time. A device  10 ′ can be actuated one time or as many times as necessary. The freeze and thaw process of the ice ball can be repeated with further actuations of the device  10 ′ as necessary. 
     Any type of actuator can be used to activate the metered valve assembly.  FIG. 1  and  FIG. 10  illustrate at least two types of actuators as are known by those of skill in the art. It is to be understood that the type of actuator employed is not a limitation of the present invention. 
     Each time the actuator is employed, one dose of coolant solution flows from the metered valve through the valve stem  15  or  15 ′ to the extension tube  18  or applicator tube  18 ′. In embodiments of the claimed invention the applicator tube can be a flexible straw-like device of, for example, plastic or metal. 
     An applicator head  20  or  20 ′ can be affixed to a distal end of the extension tube  18  or applicator tube  18 ′. The applicator head  20  or  20 ′ receives the coolant solution from the tube  18  or  18 ′ and pools the coolant solution over the abnormal tissue being treated. 
     Referring to  FIG. 2 , a cross-sectional view of a first applicator head  20  in accordance with the first embodiment of the present invention is shown. The applicator head  20  can include three sections: a first section,  22 , a second section  24 , and a stop  23 . 
     The first section  22  can include an extension tube slot  25 , and a distal end of the extension tube  18  can be inserted therein. Accordingly, the extension tube slot  25  should have a diameter wide enough to allow the extension tube  18  to be inserted therein and small enough so that the extension tube  18  fits securely within the extension tube slot  25 . 
     In embodiments of the system of the claimed invention, a practitioner can attach and remove an applicator head  20  relatively easily to the distal end of the extension tube  18 . Further, a proximal end of the extension tube  18  can be removed and attached relatively easily to the actuator  16 . In this manner, an applicator head and/or an extension tube can be discarded after use with one patient or one treatment area, and a new applicator head and/or extension tube can be attached when the device  10  is being used with a second patient or second treatment area. Alternatively, an applicator head and/or extension tube can be reusable by removing the applicator head from the extension tube and/or removing the extension tube from the actuator. The applicator head and/or extension tube can then be sterilized with, for example, autoclaving or a bactericidal solution, before reaffixing the applicator head to the extension tube and/or the extension tube to the actuator. 
     In alternate embodiments, an applicator head and the extension tube can be one continuous piece of material. In some embodiments of the claimed invention, the applicator head and the extension tube can be formed from separate pieces of material that are fused, welded, melted, snapped, clipped, pressure fit, or screwed together, for example, to form one continuous piece of material. 
     A stop  23  is located at the distal end of the first section  22 . The stop  23  prevents the extension tube  18  from extending past the stop  23  in the applicator head  20 . 
     A second section  24  is located at the distal end of the applicator head  20 . As coolant solution exits the extension tube  18 , the coolant solution can pass through the second section  24  and be delivered to the abnormal tissue to be treated. The distal end of the second section can be placed over or on the abnormal tissue being treated. 
       FIG. 3  illustrates a perspective view of a second applicator head  20  in accordance with the first embodiment of the present invention. As seen in  FIG. 3 , the applicator head  20  includes a first section  22 , which contains an extension tube slot  25  for receiving the distal end of the extension tube. The applicator head also includes a stop  23  for preventing the extension tube  18  from extending any further than the stop in the applicator head  20 . 
     The second section  24  of the applicator head illustrated in  FIG. 3  is conical in shape such that the distal end of the second section  24  is of a greater diameter than the proximal end of the second section  24 . The larger distal end of the second section  24  can be used to treat abnormal tissue areas of larger sizes. 
       FIGS. 4   a ,  4   b ,  4   c , and  4   d  illustrate first, second, third, and fourth cross-sectional views of an applicator head  20 , respectively, in accordance with the first embodiment of the present invention. As can be seen in  FIG. 4   a , the second section  24  of the applicator head  20  can have a relatively uniform diameter throughout. Alternatively, as seen in  FIGS. 4   b ,  4   c , and  4   d , the second section  24  can be a conical shape and increase in diameter towards the distal end of the applicator head to varying degrees. 
     The treatment area to be treated with the device  10  can be of varying size and area. Accordingly, applicator heads with varying diameters of the distal ends of the second sections can be used in connection with the device  10 . The diameter of the distal end of the second section  24  determines the size and area that the coolant solution emitted from the applicator head  20  will reach. For example, when the treatment area is small, an applicator head with a second section having a uniform diameter, as seen in  FIG. 4   a  can be used. As the size of the treatment area increases, an actuator head with a second section having larger diameters at the distal end can be used, for example, the applicator heads as seen in  FIGS. 4   b  and  4   c.    
       FIGS. 6   a ,  6   b ,  7   a ,  7   b ,  8   a ,  8   b ,  9   a , and  9   b  illustrate alternative end views and bottom opening views of an applicator head in accordance with the present invention. As seen in  FIGS. 6   a ,  6   b ,  7   a ,  7   b ,  8   a ,  8   b ,  9   a , and  9   b , the end views and bottom opening views can have varying diameters in alternative embodiments of the present invention. The diameters could be, for example, 0.125 inches, 0.25 inches, 0.375 inches, or 0.5 inches. 
     As explained above, the size of the diameter to be used in connection with a particular treatment can be determined based on the size of the treatment area. For example, when the treatment area is small, a small diameter can be used. When the treatment area is larger, a larger diameter can be used. In this manner, the size of the applicator head allows for targeted application of the coolant solution to the treatment area. The coolant solution is applied to a precisely demarcated area defined by the size of the distal end of the second section of the applicator heard. Accordingly, coolant solution is not wasted, but coolant solution is still effectively administered to the treatment area. 
       FIG. 5  illustrates a fourth cross sectional view of an applicator head in accordance with the first embodiment of the present invention. As seen in  FIG. 5 , the applicator head  20  can be, for example, 1 inch in length. The first section  22  of the applicator head  20  can be, for example, 0.5 inches in length and 0.25 inches in width. The wall of the second section  24  can be, for example, 0.0625 inches thick. It is to be understood that the exact dimensions of the applicator head are not limitations of the present invention. 
     The second section  24  of the applicator head  20  can include at least one vent hole  34 , as seen in  FIG. 3 . In embodiments of the claimed invention, the second section  24  can include, for example, four vent holes. 
     The vent holes allow air from the atmosphere to reach the treatment area. When ambient air reaches the coolant solution applied to the treatment area, an ice ball can form, and the evaporation, bubbling, and thawing processes can occur. 
     Referring now to  FIG. 11 , a perspective view of an applicator head in accordance with a second embodiment of the present invention is shown. As seen in  FIG. 11 , the applicator head  40  includes a first section  42  and a second section  44 . The second section  44  is situated at the distal end of the applicator head  40 , and the distal end of the second section  44  can be placed over a treatment area. 
     The distal end of the second section  44  can have different diameters. For example, the distal end of the second section  44  can be large enough so that the diameters of the proximal and distal ends of the second section are relatively equal, and the second section has a relatively uniform diameter throughout. Alternatively, the diameter of the distal end of the second section can be smaller than the diameter of the proximal end of the second section. The distal end of the second section can be, for example, 3 mm, 5 mm, 7 mm, 9 mm, or 12 mm. 
     The first section  42  of the applicator head  40  can include an extension tube slot  45  such that an applicator tube can be placed therein. The first section can also include, for example, four vent openings  46 ,  46 ′,  46 ″, and  46 ′″. The vent openings can be directed towards the proximal end of the applicator tube. Further, the vent openings can allow ambient atmosphere to reach the treatment area and dispersed coolant solution so that an ice ball can form, and the evaporation, bubbling, and thawing processes can occur. 
       FIG. 12  illustrates a side view of the applicator head illustrated in  FIG. 11 . As seen in  FIG. 12 , the vent openings  46 ,  46 ′,  46 ″, and  46 ′″ can be situated at the proximal end of the first section  42 . The distal end of the second section  44  can have different diameters suitable for treating skin lesions of varying size. For example, when the treatment area is small, an applicator head with a second section having a distal end with a small diameter can be used. As the size of the treatment area increases, an applicator head with a second section having larger diameters at the distal end can be used. For example, an applicator head with a distal end of the second section having a diameter as large as the diameter of the proximal end of the second section can be used such that the second section has a relatively uniform diameter throughout 
       FIG. 13  illustrates an end view of the proximal end of the first section of the applicator head illustrated in  FIGS. 11 and 12 . As seen in  FIG. 13 , the vent openings  46 ,  46 ′,  46 ″, and  46 ′″ can be defined by pieces of the first section  42  forming an “X”.  FIG. 13   a  illustrates a cross-sectional view of the line A-A in  FIG. 13 , and  FIG. 13   b  illustrates a cross-sectional view of the line B-B in  FIG. 13 . 
     As seen in  FIG. 13   a , the vent openings  46  and  46 ″ extend from the first section  42  through the second section  44  and are situated about the applicator tube slot  45 . Referring to  FIG. 13   c , a detailed view of a stop located in an applicator head is shown. The stop  43  is located at the distal end of the applicator tube slot  45  to prevent the applicator tube from extending past the stop  43  in the applicator head  40 . 
     The applicator head in accordance with the second embodiment of the present invention as shown in  FIG. 11  through  FIG. 13   c  can be, for example, 1.4 inches in length and 0.6 inches in width at its widest point. It is to be understood that the exact dimensions of the applicator head are not limitations of the present invention. 
     While the applicator heads depicted in  FIGS. 2-9   b  and  FIGS. 11-13   c  have been described above with reference to various sections, it is to be understood that an applicator head in accordance with the present invention is one continuous piece of material. The reference to various sections is merely for clarity in describing the applicator head as a whole. In embodiments of the claimed invention, the applicator head can be formed from separate pieces of material that are fused, welded, melted, snapped, clipped, pressure fit, or screwed together, for example, to form one continuous piece of material. 
     It is to be further understood that the applicator heads depicted in  FIGS. 2-9   b  and  FIGS. 11-13   c  are merely exemplary in size and shape. While the distal end of the applicator head as illustrated is round, the shape of the distal end of the applicator head can be round, oval, square, or any other shape as would be understood by those or ordinary skill in the art. 
     Applicator heads in accordance with the present invention can be made of, for example, plastic or metal. In embodiments of the claimed invention, the applicator head can be made of a clear material. In this manner, a practitioner can more effectively view and assess the treatment area, ensure that the applicator head is precisely placed over the treatment area, and see that an ice ball has been formed and maintained for a sufficient period of time. 
     From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus or method illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.