Vacuum device for treating tissus adjacent a body cavity

ES 2 365 331 T3

DESCRIPTION

Vacuum device for treating tissues adjacent to a body cavity

Field of the invention

The invention relates generally to the field of medical treatment devices. In particular, the invention relates to devices for treating a tissue surrounding a body cavity, such as, for example, an area from which a cancerous, precancerous, or other type of tissue has been removed.

Background of the invention

In the diagnosis and treatment of certain medical conditions, it is often convenient to perform a biopsy in which a specimen or tissue sample is removed for pathological examination, testing, and analysis. The biopsy typically results in a biopsy cavity that occupies the space previously occupied by the tissue that was removed. As I have learned, obtaining a tissue sample by biopsy and subsequent examination are typically used in the diagnosis of cancers and other malignant tumors, or to confirm that a suspicious lesion or tumor is not malignant. Treatment of biopsy-identified cancers may include subsequent removal of the tissue surrounding the biopsy site, leaving an enlarged cavity within the patient's body. Cancer tissue is often treated by radiation, chemotherapy, or heat treatment (eg, local application of heat, cryogenic therapy, and other treatments to heat, cool, or freeze tissue).

Cancer treatment may be aimed at a natural cavity, or an existing cavity in the patient's body from which tissue has been removed, typically as a consequence of removal of cancerous tissue in the course of a biopsy or surgery. surgical For example, US Patent 5,429,582 to Williams, US Patent 5,913, .813 to Williams; US Patent 5,931,774 to Williams; US Patent 6,022,308 to Williams, US Patent 6,083,148 to Williams, and US Patent 6,413,204 to Winkler et al. describe devices for implantation within a cavity produced by the removal of cancerous tissue, which can be used to administer cancer treatments to surrounding tissue. One form of radiation treatment used to treat cancer near a body cavity that remains after tissue removal is "brachytherapy" in which a source of radiation is placed near the area to be treated. Document US 5913813 discloses the distinctive features of the preamble of claim 1.

Williams and colleagues describe implantable devices for treating tissue surrounding a cavity that remains after surgical removal of other cancerous tissue that includes an inflatable balloon constructed for placement within the cavity. Said devices can be used to apply one or more therapies between radiation therapy, chemotherapy, and thermal therapy on the tissue surrounding the cavity from which the tissue was excised. The balloon can be filled with a treatment fluid delivered through a conduit from a receptacle, syringe, or other means, or it can receive a solid radiation source located within the balloon. In this way, radiation treatment can be applied to the tissue adjacent to the balloon by placing a radioactive material, such as radioactive "seeds" inside the balloon, or by filling the balloon with a liquid or suspension that contains radioactive material. Multiple treatments can be applied simultaneously. For example, radioactive seeds can be placed within the balloon to effectively irradiate the tissue surrounding the balloon, and the balloon filled with a hot fluid at the same time to provide heat treatment. After a relevant time, the hot fluid and / or radioactive seeds can be removed. Said treatments, combined or applied in any other way, can be repeated if desired.

For example, a "MammoSite® Radiation Therapy System" (Proxima Therapeutics, Inc. Alpharetta GA 30005 USA) includes a balloon catheter with a radiation source that can be positioned within a resection cavity. of a tumor within a breast after a mammary lumpectomy. It can deliver a prescribed dose of radiation from within the tumor resection cavity to the tissue surrounding the original tumor. The radiation source is typically a solid radiation source; however, a liquid radiation source can also be used with a balloon catheter located within a body cavity (eg, lotrex®, Proxima Therapeutics Inc). The radiation source can be withdrawn after each treatment session, or it can remain in position as long as the balloon remains within the body cavity. Inflatable treatment delivery devices and systems, such as MammoSite® RTS and similar devices and systems (for example, GliaSite®RTS (Proxima Therapeutics Inc.)), are useful for treating cancer in tissue adjacent to a cavity. of the body.

However, radiation, chemotherapy, heat treatment, and other cancer treatments often have deleterious effects on healthy tissue in addition to their desired effects on cancerous tissue. In treatments of the type indicated, care must be taken to direct the maximum effects of the treatment on diseased tissue while minimizing its administration or effects on healthy tissue. For example, radiation treatment can be most effective when all surrounding tissue regions

ES 2 365 331 T3 receive the same radiation dose, and when the radiation dose received by the most distant tissue is as small and uniform as possible. However, tissue cavities are typically not uniform or regular in size and shape, so there are often differences in the doses applied to different regions of the surrounding tissue, including "hot spots." and regions of relatively low dose.

Accordingly, there is a need in the art for improved devices for delivering cancer treatment to the area of ​​a cavity within a patient's body.

Summary of the invention

The present invention provides a device for irradiating a tissue that forms at least in part a body cavity according to claim 1. Further preferred aspects of the invention are offered according to the dependent claims. The invention provides assemblies, devices, and systems for treating tissue adjacent to a body cavity, such as a cavity formed by removing tissue from a patient. In devices exhibiting the distinctive features of the invention, a vacuum is applied to pull tissue toward a treatment assembly located within the body cavity. Assemblies and devices incorporating the features of the invention include a vacuum management element configured to apply a vacuum. A vacuum delivery member may include a vacuum conduit, and may also include a vacuum port. A vacuum delivery element can be at least partially configured to surround or enclose a treatment assembly. A treatment setup can be configured to deliver a treatment, such as radiation therapy, chemotherapy, heat therapy, or other treatment, to tissue adjacent to a body cavity. A treatment assembly may include a treatment delivery element configured to contain a treatment material, such as a radioactive source. A treatment assembly can include an inflatable balloon, which can be disposed, at least in part, around a treatment delivery element.

Assemblies and devices incorporating the distinctive features of the invention may include a vacuum delivery element, such as a sheath or balloon configured to provide an effective vacuum to apply suction to tissue adjacent to the assemblies and devices. Vacuum delivery elements are preferably configured to apply suction to tissue adjacent to treatment delivery mounts, such as an inflatable treatment delivery device. Suction is effective in pulling surrounding tissue proximate to the surface of a treatment assembly, or to a vacuum delivery element (such as a sheath or balloon) that at least partially surrounds or closes a treatment assembly, to form the tissue that lines the inside of the body cavity for optimal treatment. Treatment can be, for example, radioactive therapy, chemotherapy, heat therapy, or other treatment modality delivered by the device. The treatment assembly may include an inflatable treatment assembly such as an internal balloon assembly configured to be at least partially enclosed by a vacuum delivery element, such as a sheath or balloon. A sheath may be configured to at least partially enclose a balloon temporarily, after placement on or around an internal balloon. A balloon can be configured to at least partially enclose a balloon after placement on or around an internal balloon.

The devices may also include an enclosure assembly (which may comprise a sheath assembly or a balloon assembly) comprising a vacuum conduit and a fluid-permeable enclosure wall (for example, a sheath or balloon wall). a wall of the balloon) configured to partially or completely enclose an internal balloon assembly. Such an enclosure assembly may be effective in providing the vacuum or a vacuum path to an interspace outside of the inner balloon assembly. An interspace may include a space provided between the inner balloon assembly and the sheath assembly or an outer balloon assembly. The enclosure assembly is preferably operatively connected to a vacuum conduit effective to provide a vacuum to the interspace. Systems exhibiting the distinctive features of the invention include such devices and also include a vacuum source configured to operatively connect to the vacuum conduit. In embodiments of the devices that have the distinctive characteristics of the invention, a wall of the enclosure that is impermeable to fluids can have one or more orifices configured to allow the passage of fluid. They may be made of a fluid-permeable material, such as a fluid-permeable woven material, or they may be otherwise fluid-permeable. The space between the inner balloon and the enclosure can be prevented from collapsing, even in the presence of a suction from a vacuum supplied through the vacuum conduit, by means of separating elements arranged on the wall of the inner balloon; or on the wall of the enclosure, or on both. In alternative embodiments, the spacing elements arranged within an interspace may be independent of both the wall of the inner balloon and the wall of the enclosure.

An embodiment of a device for treating tissue adjacent to a body cavity exhibiting the distinctive features of the invention further comprises an internal balloon assembly, which may include or be operatively connected to an inflation conduit. configured to allow the passage of a fluid. The devices may also have an internal balloon that comprises a compliant wall of the internal balloon that defines an internal lumen. Said internal balloon may be operatively connected to a

ES 2 365 331 T3 inflation conduit to allow the passage of fluid through an inflation conduit and into an internal lumen to inflate the internal balloon with the fluid.

An enclosure wall preferably comprises a flexible material, more preferably an elastic flexible material, although, in embodiments of the invention, an enclosure wall may comprise an inelastic flexible material. In embodiments of the devices and systems representing the characteristics of the invention, a wall of the enclosure having the characteristics of the invention, a wall of the enclosure comprises a polymer, for example a biocompatible polymer, preferably a polymer resistant to the radiation. Suitable polymers include polyolefins, such as polyethylene and polypropylene, polyurethanes, polyester, polyvinyl chloride, polystyrene, thermoplastic polymers such as C-Flex® (Consolidated Polymener Technologies, Inc., Clearwater Fl 33762) block polymers, such as example Kraton ™ (Kraton Polymers, Houston TX 77208) an ionomer, such as Surlyn® (Dupont, Wilmington DE 19880), nylon, latex rubber, silicon rubber (eg SILACTIC ™, Dow Corning, Midland, ML).

Devices and systems that exhibit the distinctive features of the invention include internal balloon assemblies configured to enclose a treatment material, such as radioactive material, chemotherapeutic agents, and heat treatment materials (eg, materials that exhibit a higher temperature). about 37 ° C).

The invention also provides methods for treating tissue adjacent to a body cavity, comprising contacting tissue adjacent to a body cavity with a sheath or with an external balloon having a fluid-permeable wall of the body. a device that presents the distinctive characteristics of the invention; and applying an effective vacuum to enhance contact between the fluid-permeable wall and the tissue. Additional procedures may include administering an inflation fluid over the lumen of the inner balloon via an inflation conduit to inflate a compliant balloon. In embodiments of the methods of the invention, the internal balloon assembly comprises a treatment assembly, such as a MammoSite RTS or similar inflatable treatment delivery device. The procedures may include the placement of a treatment material within the device and may also include the repositioning of the treatment material.

Body cavities are typically not uniform in size or regular configuration. Devices, systems, and methods exhibiting the distinctive features of the invention use suction to pull tissue against the surface of the device within a body cavity, ensuring satisfactory contact between the device and body tissue and providing control over the surface of the device. separation between the tissue and the device, including control over the distance of the treatment material contained within the devices. The tissue that lines a body cavity on the inside that is held in proximity to, or in contact with, the devices that have the distinctive characteristics of the invention, constitutes a uniform and controlled surface, unlike the tissue that lines a cavity on the inside. of the body into which a prior art treatment device has simply been inserted, but which does not press the tissue in the desired orientation and position. The control of the distance, spacing, and amount of tissue contact provided by the devices, systems, and methods of the present invention offers the advantages of improved treatment of tissue adjacent to the body cavity. Such improvements may include more uniform dosing, a reduction in "hot spots", shorter treatments due to a greater correlation between desired and effective dosages, and a reduction in the number of underdosed sites.

Brief description of the drawings

Figure 1 is a partially cutaway perspective view of an unprotected system of the invention configured to deliver a treatment within a tissue cavity existing within the body of a patient while providing an effective vacuum to press tissue into contact. with an external balloon surface.

Figure 2 is a longitudinal cross section of the system of Fig. 1 taken along line 2-2.

Figure 3 is a cross-sectional view of the system of Fig. 1 taken along line 3-3.

Figure 4A is a cross-sectional view of a system of Fig. 1 showing a sector-shaped section of the balloon walls between lines 4-4 for an embodiment in which an outer wall has spacers. .

Figure 4B is a cross-sectional view of the system of Fig. 1 showing a sector-shaped section of balloon walls between lines 4-4 for an embodiment in which an inner wall has spacers.

In Figure 5A they show a perspective view of a system not included in the invention, in which an external balloon assembly, in the form of a sheath, is being fitted over an internal balloon assembly.

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Figure 5B shows a cross-sectional view of the assembled inner and outer balloon assemblies in the Figures after placement within a cavity within a patient's breast and prior to inflation of the inner balloon assembly.

Figure 5C shows a cross-sectional view of the assembled inner and outer balloon assemblies of Figure 5A after inflation of the inner balloon assembly.

Figure 5D shows a cross-sectional view of the assembled external and internal balloon assemblies of Figure 5A after the application of vacuum to the lumen separating the internal balloon assembly and the external balloon assembly, after placement of a radioactive mount within the inner balloon mount.

Figure 6A is a perspective view of a system incorporating the hallmarks of the invention that includes a vacuum delivery element configured to partially enclose an internal balloon assembly.

Figure 6B is a cross-sectional view of the system of Figure 6A taken along line 6B-6B

Detailed description of the preferred embodiments

The present invention provides devices for delivering a treatment, such as cancer treatment, into a cavity located within the body of an animal. The devices and procedures that present the distinctive characteristics of the invention can be used for treatment up to the interior of a biopsy area or to the interior of a cavity that remains after the removal of cancerous tissue and the removal of a body from a human patient. A tissue is applied to enhance contact between a treatment delivery assembly within a body cavity and the tissue surrounding the body cavity. A vacuum path around the treatment assembly is provided by devices, systems, and procedures that incorporate the distinctive features of the invention. Vacuum can be applied to tissue through one, two, or multiple vacuum holes. A vacuum port can be an existing port of a vacuum delivery conduit, an port of a sheath or a balloon connected to a vacuum delivery conduit. A fluid impermeable wall or a portion of a fluid permeable wall may be effective to serve as a vacuum port.

Figure 1 is a perspective view of a system 10 not within the scope of the invention and illustrating a device 12 having an outer balloon 14 that encloses an inner balloon 16 (shown in the cutout portion of the illustration) , a shaft 18, and a connector 20. The outer balloon 14 comprises a sheath assembly around the inner balloon 16. The outer balloon 14 thus constitutes an example of an enclosure assembly, and forms a wall of the enclosure around the inner balloon 16. The outer balloon 14 comprises, at least in part, a permeable wall; As illustrated in Figure 1, the outer balloon 14 has holes 22 that allow the fluids of the balloon 14 to spread. In alternative embodiments an outer balloon 14 may be made of substantially continuous fabric or other materials that are permeable to fluids. In further embodiments, an enclosure wall or assembly, such as an outer balloon, may comprise a net, mesh, lattice, or other discontinuous structure. Ports 22 (or fluid permeable material) allow fluids to pass through outer balloon 14 into interspace 24 provided outside inner balloon 16. Interspace 24 provides a vacuum path adjacent to the balloon inner 16. When at least a portion of outer balloon 14 is disposed adjacent to inner balloon 16, interspace 24 is located between outer balloon 14 and inner balloon 16.

Inner balloon 16 defines an inner lumen 26 within which a delivery shaft 28 may be at least partially contained. As shown in Figure 2, a treatment material 30 may be, permanently or transiently, disposed within the shaft 28. A probe 32 configured to move within the distribution shaft 28 may be used to position the treatment material 30, including placing the treatment material 30 within and retrieving the positioning material 30 from the interior of the distribution shaft 28. A Vacuum conduit 34 may be part of, or may be contained within, a shaft 18 and may be operatively connected to interspace 24. The shaft 18 may also include or contain an inflation conduit 36 ​​configured to allow the passage of the inflation fluid into the interior lumen 26. The passage of the inflation fluid into the interior lumen 26 is efficient. to inflate the inner balloon 16. The inflation fluid can be any suitable fluid either a gas or a liquid, and is typically inert. The inflation fluid, when it is a gas, such as air, nitrogen, carbon dioxide or other gas, the inflation fluid, when it is a liquid, can be water, a saline solution, mineral oil, or another liquid. In some embodiment, an inflation fluid may be effective to absorb radiation to, for example, moderate or adjust a dose of radiation delivered to a patient's tissue from a radioactive treatment material 30 contained within the delivery shaft 28.

The vacuum applied to the interspace 24 is effective to deliver a treatment within a body cavity 38 within the body of a patient, being effective to press the surrounding tissue until it contacts at least a portion of the surface of the outer balloon 14.

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The outer balloon 14 shown in Figs. 1-5 is illustrated as a balloon that is configured to permanently or semi-permanently enclose the inner balloon 16 or the inner balloon assembly. Said enclosure can be partial or complete. It should be understood that the external surface of a device and system incorporating the distinctive features of the invention may also be a sheath 50 configured for deployment on and around an internal balloon assembly 14. In further embodiments, an enclosure may be, for example, a mesh, mesh, lattice, or other discontinuous structure.

Figure 2 is a longitudinal cross-sectional view of the system of Fig. 1 taken along line 2-2 showing in cross-section, for example, the relative positions of treatment material 30 of an internal balloon 16 and external balloon 14 or sheath 50. Figure 2 includes cross-sectional views of shaft 18 including views of delivery shaft 28 of vacuum conduit 34 and inflation conduit 36. Figure 3 is a cross-sectional view of the system of Fig. 1 taken along line 3-3 showing outer balloon 14 and holes 22 through it, inner balloon 16 disposed within outer balloon 14 , delivery shaft 28, and probe 32.

Figures 4A and 4B show portions of outer balloon 14 and inner balloon 16, as indicated in Figure 1, including interspace 24 and spacers 40 which serve as effective separating elements to maintain the permeability of the space. intermediate 24 even under the influence of the vacuum supplied through the vacuum conduit 34. The spacers 40 can be part of the outer balloon 14 or the inner balloon 16, or both. A spacer 40 may be a bulge, button, ridge, or other distinctive feature that extends into the inner surface 42 of the outer balloon 14, or that extends outwardly from an outer surface 44 of the outer balloon 14. Likewise Or, alternatively, a spacer 40 may be an object that is located within an interspace 24 that is spaced from the inner balloon 14 or the outer balloon 16. As shown in Figures 4A and 4B, the spacers 40 can be the projections that extend on an inner surface 42 of the outer balloon 14 or an outer surface 44 of the outer balloon 14.

Figures 5A and 5D illustrate an example of the coupling of an external balloon assembly 46 (which includes an external balloon in the form of a sheath 50), onto an internal balloon assembly 48 that includes an internal balloon 16, which does not are included in the scope of the invention. Figure 5B shows the assembled outer 46 and inner 48 balloon assemblies of Figure 5A after placement within a cavity 38 within a patient's breast 52 and prior to inflation of the inner balloon assembly 48. In Figure 5C, the inner balloon assembly 48 has been inflated by passing the inflation fluid through the inflation conduit 36, pressing some parts of the outer balloon assembly 46 from the outer surface 54 until contacting the portions of the tube. inner surface 56 of body cavity 38. Note, however, that since most cavities 38 have uneven internal surfaces, there will typically be poor and intermittent conduit between external surface 54 of sheath 50 (or external balloon 14 or in alternative embodiments). and the inner surface 56 of cavity 38, as shown in Figure 5C.

Figure 5D shows the assembled outer 46 and inner 48 balloon assemblies of Figure 5A after application of vacuum through the vacuum conduit 34 over the interspace 24 that separates the inner balloon 16 and the sheath 50 (outer balloon 14 ). Treatment material 30 is in position within delivery shaft 28. Note that inner surface 56 of cavity 38 has been split into intimate contact with outer surface 54 of sheath 50. Such intimate contact configures the inner surface 56 placing it in an optimal configuration for the application of treatment by a treatment material 30. For example, radiation treatment by a radiation treatment material 30 is enhanced by the proper placement of adjacent tissue to provide appropriate irradiation. Irradiation levels can vary widely depending on whether adjacent tissue in tissue cavity 38 is at different, uneven, or inappropriate distances from the radiation source. The application of an effective vacuum to pull the tissue to obtain better contact with the device 12, for example better contact with the outer surface 54 of the sheath 50, is effective in improving the delivery of radiation treatment from a material 30 radioactive treatment.

Figure 6A illustrates a system incorporating distinctive features of the invention including a vacuum supply element comprising an enclosure 60 having ribs 62 configured to partially enclose an internal balloon assembly 48. Vacuum is supplied to the interspace. 24 via vacuum ports 64 operatively connected to vacuum conduit 34. As shown in cross section in Figure 6B, ribs 62 serve as effective spacing elements to provide vacuum paths within interspace 24 between tissue surface 56 and outer surface 44 of the inner balloon assembly. 48.

Procedures for treating tissue adjacent to a body cavity 38 are not within the scope of the invention. Among these are methods of delivering a treatment to tissue adjacent to a device 12 that incorporates the distinctive features of the invention. For example, a procedure for treating tissue adjacent to a body cavity 38 includes contacting the tissue adjacent to body cavity 38 with a sheath 50 or an external balloon 14, and applying a vacuum via the conduit vacuum 34. Vacuum may be effective to pull adjacent tissue into and into contact with sheath 50 or outer balloon 14 and thus enhance contact between outer wall 54 and tissue. Inflation Fluid Management

ES 2 365 331 T3 to an internal balloon 16 by means of an inflation conduit 36 ​​to inflate the internal balloon 16 is also effective to enhance contact with the adjacent tissue, serving to position the external balloon 14 or the sheath 50 closer to the tissue than it would be in the absence of internal balloon inflation 16. In preferred embodiments, the inner balloon assembly 48 comprises a treatment delivery device, such as a Mammosite RTS (Proxima Therapeutics, Innc; Alpharetta GA 30005) or similar device.

Additional procedures include the placement of a treatment material 30, such as a radiation source, within the device (eg, by placement of a delivery shaft 28). A radiation source, such as a solid radiation source (such as brachytherapy seeds) can be introduced into delivery shaft 28 with probe 32 or by other means. Other solid treatment materials 30 can similarly be introduced into a delivery shaft 28 with a probe 32 or by other means. A source of liquid radiation (for example, lotrex®, Proxima Therapeutics Inc; Alpharetta Inc. Ga) can be introduced into a delivery shaft 28 by a flow of fluid, by the force of gravity, by pressure applied by a syringe or other pressure source, or by other means to deliver a fluid into a space. . Similarly, hot liquids and other liquid treatment materials 30 can be introduced into a delivery shaft 28 or an internal balloon 16 (through the traction conduit 36), by the force of gravity, by an applied pressure. by syringe or other pressure source, or by other means to deliver fluid into a space.

Some treatment regimens may include periodic or episodic treatment in which radiation or other treatment is applied during a treatment period and treatment is stopped during a recovery period. Such periodic or episodic treatments can be repeated, so that the treatment is applied during a first treatment period, is stopped during a first recovery period and then the treatment is applied again during a second treatment period. Treatment period and additional recovery periods can also be used if necessary. Thus, the procedures may also include removal of the radiation source or other treatment material 30 from the delivery shaft 28 and may also include replacement of treatment material 30.

Although a cavity 38 is typically an artificial cavity that remains after tissue removal with biopsy, surgery, or other medical procedure, a body cavity can be a natural body cavity. For example, devices 12 can be inserted into a bladder for the treatment of bladder cancer. A suction application is effective to enhance the contact of a device 12 in that example as well. Such enhanced contact may be effective in enhancing radiation delivery for other treatment and may be effective in avoiding "hot spots" (tissue regions that receive more radiation than neighboring tissue regions receive) is one of the important advantages provided. by the present invention.

Treatment material 30 can include a chemotherapeutic agent effective to treat cancer and other abnormal conditions of the tissue surrounding a body cavity 38. In preferred embodiments, treatment material 30 includes a radiation source configured to deliver adjacent tissue to device 12.

Thus, treatment material 30 can include a radiation source that can be solid or liquid. A solid radiation source can include, for example, a radioactive iodine isotope (for example,¹²⁵it ¹³¹l), a suspension of a solid isotope, for example ¹⁹⁸ Au, ⁹⁰Y,¹⁶⁹Yb, or a gel containing a radioactive isotope. Liquid radiation sources are commercially available (eg lotrex®, Proxima Therapeutics, Inc., GA).

A solid radiation source may include brachytherapy seeds or other solid radiation source used in radiation therapy, such as, for example, a radioactive microsphere available from 3M Society of St. Paul, MN. A solid radioactive source can either be preloaded into a device 12 at the time of manufacture, or it can be loaded into a device 12 after placement within the body cavity 38 of a distal portion of the device 12. Said distal portion preferably includes outer balloon 14, inner balloon 16, and at least a portion of delivery shaft 28. Such a configuration of the solid radioactive core offers the advantage that it allows a wider range of radionuclides than if it were restricted to liquids. Solid radionuclides suitable for use with the delivery device incorporating the hallmarks of the present invention are generally currently available as brachytherapy radiation sources (eg, i-Plant ™, Med-Tec, Orange City IA) .

In general, the amount of radiation desired by the physician is a certain minimum amount that is delivered over an area approximately 0 to 3 cm away from the wall of the body cavity 38 (for example, from where a tumor has been resected) . The vacuum applied to the interspace 24 makes satisfactory contact between the tissue surrounding the body cavity 38 and the wall of the outer balloon 14 or of the sheath 50, promoting effective treatment delivery, such as administration of the radiation to surrounding tissue. It is desirable to keep the radiation in the region near the wall of the outer balloon 14 or sheath 50 as uniform as possible to prevent overexposure of the tissue at or near the wall of the reservoir. It is well known that the absorbed dose rate at a point outside the radioactive source is inversely proportional to the square of the distance between the radiation source and the target point. This

In this way, it is possible that the dose of radiation delivered to adjacent tissue may differ from that delivered to tissue disposed at more distal sites. In some cases, penetration of radiation to locations far from a device 12 is undesirable. For example, in cancer treatments such as bladder cancer, where the neoplastic tissue is generally located on the surface of the bladder, penetration is unnecessary and should be avoided.

An inflation fluid can also be a radiation absorbing fluid. For example an inflation fluid can be an X-ray contrast agent, as used in angiography, for example a barium salt (for example barium sulfate), water, a saline solution or other saline fluid thereof. type. A radiation absorbing inflation fluid which will surround a radiation source located within delivery shaft 28 serves to moderate and control the delivery of radiation from the radiation source to surrounding tissue. Such restraint and control that is obtained with the radiation absorbing inflation fluid can help to avoid the administration of an excessive amount of radiation on some surrounding portions.

Thus, in the absence of such radiation absorbing inflation fluid, it is possible that in some cases a radiation source sufficient to provide an effective dose at distances remote from a device 12 would expose tissue that is located directly adjacent to the device 12. wall of the outer balloon 14 or of the sheath 50 at an excessive radiation dose. Such excessive exposure to such tissue located near device 12 can result in necrosis of healthy tissue.

Alternatively, an inflation fluid may contain radioactive elements, either as a liquid or as a suspension, so that the inner balloon 16 is filled with a source of radiation, providing a fairly uniform source of radiation that is distributed over the inner volume of the tube. ball 16. In such embodiments, an inflation fluid thus serves as a radiation source by itself, thereby providing well-controlled amounts of radiation on surrounding tissue while minimizing site-specific irregularities in administered doses.

In embodiments of the invention in which an inflation fluid includes a radiation source, a delivery shaft 28 may contain a radiation absorbing material such that, for example, less volume of radioactive material is required than if the entire volume of a device 12 that was filled with radioactive material. Such a configuration may be advantageous when a profile that exhibits higher intensity is desired on a tissue surface with less penetration. Also, the outer balloon 14 may not be spherical, however a uniform radiation delivery profile can be obtained. Experiments disclosed in US Patent 5,918,813 to Williams are described showing that a steeper radial source gradient can be obtained using a radiation attenuation fluid within an internal chamber of a radiation delivery device similar to that in Another case would be obtained with a device featuring only a single extendable chamber (as described in US Patent 5,429,582 to Williams).