Patent Application
20120004493
Treatment agents often need to be placed at or adjacent to a site requiring treatment within a patient's body. For example, brachytherapy is a form of radiotherapy wherein a radioactive source is placed at or adjacent to a site requiring radioactive treatment within a patient's body. Brachytherapy has become increasingly important in the treatment of certain diseases, especially cancer, in that the radioactive source can be targeted to localized areas within the body to ensure effective treatment of the affected site while minimizing the risk of unnecessary damage to healthy neighboring tissues or organs.
The radioactive source is normally contained within a well-insulated source housing. The source housing is attached to a drive member or a guide wire, usually a flexible cable, which will guide the radioactive source to a targeted treatment site within the patient's body. To this end, a tubular guide, such as a hollow needle, a flexible tube or a catheter, is first placed at the targeted treatment site. Once the tubular guide is in place, the source housing, driven by the guide wire, follows the path provided by the tubular guide to the targeted treatment site. When the targeted treatment site is in an area that is not readily accessible, the path that the tubular guide traverses to reach the targeted treatment site may comprise many turns, tight angles and/or curves. The source housing, made of metal, has very limited flexibility. Thus, the guide wire needs to be solid and sturdy to propel the source housing through the tubular guide yet sufficiently flexible to guide it through curves without kinking.
The attempt to develop a guidewire with desired flexibility and sturdiness is described in U.S. Pat. No. 6,196,964. However, the structure of this patent requires use of a separate adaptor between the guidwire and capsule holding a radioactive source. It is desirable to have a device without the complexities added by the adaptor, and the risk that the connection between the guidewire and adaptor, or the connection between the adaptor and the capsule of the radioactive source and fail in use.
An exemplary system for the delivery of a treatment agent to a treatment site of a patient's body is discussed herein. The system according to the present invention includes a medical device for delivering a treatment agent to a site requiring treatment. The device comprises a source housing comprising an interior cavity for receiving a treatment agent disposed therein and a cable designed for placement of the source housing. The cable is comprised of first and second sections. The first section is connected to the housing and is closer to the housing than is the second section. The first section is formed from a first material and the second section is formed from a second material. The flexibility of the first section is greater than the flexibility of the second section due to heat treatment of at least one of the first and second materials. Preferably, for ease of manufacture, before heat treatment the first and second materials are the same, and can be the same material mixture, where the mixture comprises at least two different materials.
In one example of a system having features of the present invention, the source housing comprises an interior cavity having a radioactive source disposed therein. A cable comprising a first section and a second section made from a same material mixture throughout the first section and the second section is used. The first section has a flexibility greater than that of the second section.
Another feature discussed herein is a guide wire for the delivery of a radioactive source to a treatment site of a patient's body. In one example, a guide wire is described comprising an elongated cable comprising a first section and a second section made from a same material mixture throughout the first section and the second section. The device wherein the material mixture comprises a plurality of first filaments and a plurality of second filaments, the first filaments made from a first material and the second filaments made from a second material. The device wherein the first material has a first annealing temperature and the second material has a second annealing temperature, which is higher than the first annealing temperature.
In yet another example, a method for forming a medical device for delivering a radioactive source to a targeted treatment site is described. The method can comprise the steps of providing a source housing comprising a radioactive source disposed therein and providing a cable comprising a first section and a second section made from a same material mixture throughout the first and second sections. The material mixture comprises a plurality of first filaments and a plurality of second filaments, the plurality of first filaments made from a first material and the plurality of second filaments made from a second material. The first material has a first annealing temperature and the second material has a second annealing temperature, which is higher than the annealing temperature of the first material. The method further comprising the steps of annealing the first section to at least the first annealing temperature and connecting the source housing to the cable.
Consequently, the first section becomes more flexible relative to the second section, although both the first and second sections are formed from the same identical material(s) throughout and have the same starting flexibility characteristics. As such, a further aspect of the present device, system, and method may be understood to include a cable having a first state and a second state and wherein a section of the cable is more flexible in the second state than when in the first state.
In a further example, a multi-strand working cable is described comprising a first state in which the entire cable comprises a first flexibility and a second state in which the same working cable comprises the first flexibility and a second flexibility, which is greater than the first flexibility. The cable also comprises a more flexible section in the second state than for the same section when in the first state. For example, the first section of the cable is more flexible in the second state than when in the first state.
In an exemplary embodiment, several factors, including material selections, thickness of the filaments and relative quantities of the first versus second filaments, can be manipulated to obtain a desired flexibility for the various sections of a cable for use in brachytherapy. Thus, a further aspect of the present method is understood to include a method for regulating the flexibilities of the first and second sections of a guide wire by varying the material and/or thickness and/or quantity of the first and second filaments that make up the cable.
The various embodiments of the present delivery device, systems, and associated methods now will be discussed in detail with an emphasis on highlighting the advantageous features. These embodiments depict the novel and non-obvious delivery device shown in the accompanying drawings, which are for illustrative purposes only. These drawings include the following figures, in which like numerals indicate like parts:
The detailed description set forth below in connection with the appended drawings is intended as a description of the presently preferred embodiments of devices and methods related to the delivery of a radioactive source to a treatment site within a patient's body and are not intended to represent the only forms in which the present invention may be constructed or utilized. The description sets forth the features and the steps for constructing and using the device in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and structures may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention. As denoted elsewhere herein, like element numbers are intended to indicate like or similar elements or features.
As used herein, the terms “first”, “second”, “proximal”, and “distal” are meant to distinguish different items, sections, or locations only for similar features or structures and for reference purposes but not to limit their scope. For example, a first material and a second material can be reversed by changing one's perspective without changing the scope of the two materials, unless the context indicates otherwise. The source housing can be connected to the cable before or after heat treatment such as by annealing. As used herein, the term “flexible” means capable of being bent to flex, such as being bent repeatedly without injury or damage.
In one embodiment, the source housing 20 comprises a tubular body 22 having a cavity 24 for receiving a radioactive source 26. The radioactive source 26 includes naturally occurring radioactive materials, such as radium-226, or isotopes produced from neutral activation or nuclear fission, such as Iridium-192, Palladium-103 or Ytrium-90. In alternative embodiments, the radioactive source 26 comprises a mixture of radioactive materials. The radioactive source 26 is encapsulated in the cavity 24 of the source housing 20 for use to deliver to the treatment site. In one embodiment, the cavity 24 is sealed at its front end by a plug or cap 28, which is attached to the body 22 using conventional means, such as welding. In one example, the housing is formed with an integral plug 28 and the source housing is placed into the interior cavity via the rear opening 14, which is also used to attach the source housing 20 to the guide wire 40. The attachment can be referred to as a connecting means 30. In a specific embodiment, the connecting means 30 is a weld. In alternative embodiments, the connecting means 30 includes an interference fit wherein an end of the guide wire 40 is structured to project into the opening end 14 of the tubular body 22, such as by way of a simple snap fit arrangement or by crimping the open end.
Referring again to
In one embodiment, the cable 42 comprises a plurality of contiguous sections unitarily formed from a same material or material mixture extending between the proximal end 75 and the distal end 85. As used herein, unitarily formed is understood to mean the same throughout or monolithically formed between the first section and the second section in a longitudinal direction. Along a cross-sectional direction, the first and second sections may have a single large gauge cable or a plurality of strands forming a cable with each cable or strand being unitarily formed in the longitudinal direction. In one embodiment, the cable 42, which is formed from the same uninterrupted material(s) from the proximal end 75 to the distal end 85, comprises at least two sections having different flexibility characteristics. In another embodiment, the cable 42 comprises a plurality of sections having different flexibility characteristics, such as three or more sections with different flexibility characteristics. In one example, the cable 42 from the proximal end 75 to the distal end 85, and up to the connecting means 30 that joins the source housing 20 to the guide wire 40, does not incorporate a weld or any attachment means. In another example, the guide wire 40, without any attachment means between the proximal end 75 and the distal end 85, comprises at least two sections having different flexibility characteristics.
Referring again to
In a specific embodiment, the first section 44 and the second section 46, unitarily or singularly formed from a same material or material mixture, have different flexibility characteristics. In a preferred embodiment, the first section 44 has a greater flexibility than that of the second section 46. In another embodiment, alternating flexible and less flexible sections extend the whole length of the guide wire of the second section 46 to the proximal end 75. In use, the stiffer and longer second section 46 provides the guide wire 40 with sufficient rigidity to push the source housing 20 through the tubular catheter and the more flexible first section 44 allows the source housing 20 to readily move through the bends and curves of the tubular guide.
In one embodiment, the cable 42 is singularly formed from a single strand cable, i.e., a large gauge wire. In another embodiment, the cable 42 is made from a plurality of filaments or strands. In one embodiment, the cable 42 comprises a mixture of filaments made from at least two different materials. In a specific embodiment, the cable 42 comprises a mixture of filaments made from three or more different materials. The different flexibility characteristics may be formed by treating the cable after forming it, as further discussed below.
The cable 42 of the instant medical device comprises contiguous first and second sections 44 and 46 that are unitarily made from the same material mixture, such as a mixture of first filaments 48 and second filaments 50, but have different flexibility characteristics. By material mixture, the cable is understood to mean a single material mixture, such as NiTi, or two or more mixtures, which include strands or filaments made from different materials, such as SS, NiTi, and Copper or a different shaped-memory alloy. As described, the first section 44 has a flexibility characteristic that is greater than that of the second section 46. In another embodiment, the cable 42 is made from a single wire that has different flexibility sections, which may be made by annealing one section of the single wire and not the other.
In one embodiment, electrical resistance, thermal radiation, or other known conventional heating means may be used to anneal the section or sections of the cable to be annealed. The annealing process may further include cooling the adjacent section of the section to be annealed. For example, a coolant, such as a cool gas stream or a liquid, may be used to keep the section adjacent the section to be annealed cool to prevent unwanted annealing.
Thus, an aspect of the present assembly and method is understood to include a multi-strand cable comprising strands made from at least two different materials, which are the same from a distal end and outside of the distal end, such as towards the proximal end. For easy reference, the cable having the different properties may be referred to as a “working cable”. The multi-strand working cable comprises a first state in which the entire cable comprises a first flexibility and a second state in which the same working cable comprises the first flexibility and a second flexibility, which is greater than the first flexibility. The cable also comprises a more flexible section in the second state than for the same section when in the first state. For example, the first section 44 of the cable is more flexible in the second state than when in the first state.
In a specific embodiment, the cable 42 comprises a mixture of first filaments 48 made from a metal alloy, such Nickel Titanium or NiTi, and second filaments 50, made from a high tensile strength material, such as stainless steel. In one embodiment, the number of strands of first filaments 48 is the same as the number of strands of second filaments 50. In another embodiment, the number of first filaments 48 is less than the number of second filaments. In still yet another embodiment, the number of first filaments 48 is greater than the number of second filaments. Stainless steel has an annealing temperature above 1040° C. versus an annealing temperature of about 400° C. for NiTi.
Referring again to
Thus, aspects of the present device and method are understood to include a guide wire for delivering a radioactive source to a targeted treatment site, the guide wire comprising contiguous first and second sections, unitarily formed from a same material mixture, and wherein the first and second sections have different flexibility characteristics.
A further aspect of the device and method is understood to include a guide wire for delivering a radioactive source to a targeted treatment site; the guide wire comprising a cable comprising a mixture of first filaments and second filaments. The first filaments are made from a first material and the second filaments are made from a second material, and wherein the first material and the second material have different annealing temperatures.
A further aspect of the present method is understood to include a method for forming a medical device for delivering a radioactive source to a targeted treatment site, said method comprising the step of providing a source housing having a radioactive source positioned therein. The method further comprising the step of providing a cable having contiguous first section and second section, the first section and the second section are unitarily made from a same material mixture, and wherein the first section has a flexibility that is greater than that of the second section. The method further comprising the step of connecting the first section to the source housing.
A further aspect of the present method is understood to include a method for making a guide wire for delivering a radioactive source to a targeted treatment site within a patient's body comprising the step of providing a cable having a first section and a second section, the cable comprising a mixture of first filaments made from a first material and second filaments made from a second material, wherein the first material has a first annealing temperature that is lower than the annealing temperature of the second material. The method further comprising the step of annealing the first section at the first annealing temperature.
The relative degree of flexibility of the first section 44 may be controlled by material selection of the first filaments 48 and/or second filaments 50. In one embodiment, as set forth above, the first filaments 48 are made of NiTi alloy and the second filaments 50 are made of stainless steel. For a NiTi alloy/stainless steel product, the heat treatment can be from about 400 to about 450° C. for about 30 to about 60 minutes followed by a water quench at room temperature. In alternative embodiments, as non-limiting examples, the first filaments 48 may be made from aluminum, copper, nickel, chromium alloys and/or alloys thereof and the second filaments 50 may be made from any suitable metals and/or metal alloys. The lower the annealing temperature of the first material 52 from which the first filaments 48 are made, the more flexible the first filaments 48 can become upon annealing. Thus, a cable comprising first filaments 48 made from aluminum alloys having an annealing temperature in the range of 300-410° C. will have a more flexible first section 44 than a cable comprising first filaments 48 made of copper alloys that have an annealing temperature range of 700-800° C. Thus, the degree of flexibility of the first section 44 and of the second section 46 can be manipulated by material selections of the first and second filaments. Furthermore, use of shaped memory alloys (SMAs), such as NiTi, copper-zinc-aluminum-nickel, and copper-aluminum-nickel, allow for greater bending due to well known pseudo-elasticity properties of SMAs.
Other than material selection, the relative degree of flexibility of the various sections of the cable 42 may be controlled or regulated through, among other factors, the thickness and the number of the first filaments 48 versus the second filaments 50, as further discussed below. Also, different sections of the guide wire may be annealed so that the same guide wire may have more than three different sections of different flexibility characteristics.
Referring again to
Furthermore, in addition to material selection and thickness of the filaments, the relative numbers of first filaments 48 and second filaments 50 may also control the degrees of flexibility of the first and second sections 44, 46 of the cable 42. In one example, the cable 42 comprises a quantity N1 of first filaments 48 and a quantity N2 of second filaments 50. In one embodiment, the quantities N1 and N2 may be the same. In another embodiment, N1 is greater than N2. In another example, N1 is less than N2. In this case, at a given annealing temperature, the higher the number of the first filaments 48, the more flexible the first section 44 can become. Thus, the number of the first filaments 48 relative to the number of the second filaments 50 can be manipulated to obtain a desired flexibility for the first section 44 relative to the second section 46.
In an exemplary embodiment, the above-discussed factors, including material selections, thickness of the filaments and relative quantities of the first and second filaments, can be manipulated to obtain a desired flexibility for the various sections of the cable 42. Thus, a further aspect of the present method is understood to include a method for regulating the flexibilities of the first and second sections of the guide wire by varying the material and/or thickness and/or quantity of the first and second filaments.
Many alterations and modifications may be made by those having ordinary skill in the art, without departing from the spirit and scope of the invention. For example, rather than making a cable from a mixture of materials, a single material whose flexibility can be either increase or decreased by treatment, such as by heat treatment, can be used. If treatment increases flexibility, then the first section is heat treated. If treatment decreases flexibility, then the second section is treated. In addition, the cable need not be made with two types of filaments, but can be made with a filament surrounded or impregnated with a material, such as a polymerizable plastic, wherein treatment can change flexibility of any of the materials used for making the cable. Moreover, the invention is not limited to heat treatment, but can be used with any processing that can be used to change flexibility, such as cold treatment, a chemical processes such as acid wash or polymerization process initiated by heating a catalyst or use of UV light, or light of other wavelength. Also, although the present invention has been described with respect to using radioactive sources for patient treatment, other treatment agents can be used, such as drugs and other therapeutic agents. Therefore, it must be understood that the illustrated embodiments have been set forth only for the purposes of examples, and that the embodiments should not be taken as limiting the invention as defined by the following claims. The following claims are, therefore, to be read to include not only the combination of elements which are literally set forth, but all equivalent elements for performing substantially the same function in substantially the same way to obtain substantially the same result. The claims are thus to be understood to include those that have been illustrated and described above, those that are conceptually equivalent, and those that incorporate the ideas of the invention.
