Abstract:
A catheter assembly for delivering a radiation source into a body cavity includes a catheter shaft having a distal end and a proximal end. An inflatable balloon is coupled to the catheter shaft between the distal end and the proximal end. A dose delivery lumen extends along the catheter shaft between the proximal end and the distal end. The dose delivery lumen is configured to receive the radiation source. A radioabsorptive portion is surrounded by the inflatable balloon.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a divisional application of U.S. patent application Ser. No. 11/155,789, entitled “VACUUM DEVICE AND METHOD FOR TREATING TISSUE ADJACENT A BODY CAVITY”, filed Jun. 17, 2005, now U.S. Pat. No. 7,935,044 which is a continuation of U.S. patent application Ser. No. 10/290,002 filed Nov. 6, 2002, now U.S. Pat. No. 6,923,754, each of which is incorporated herein in its entirety by reference and from which priority is claimed. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to the fields of medical treatment devices and methods. In particular, the invention relates to devices and methods for treating tissue surrounding a body cavity, such as a site from which cancerous, pre-cancerous, or other tissue has been removed. 
     BACKGROUND OF THE INVENTION 
     In diagnosing and treating certain medical conditions, it is often desirable to perform a biopsy, in which a specimen or sample of tissue is removed for pathological examination, tests and analysis. A biopsy typically results in a biopsy cavity occupying the space formerly occupied by the tissue that was removed. As is known, obtaining a tissue sample by biopsy and the subsequent examination are typically employed in the diagnosis of cancers and other malignant tumors, or to confirm that a suspected lesion or tumor is not malignant. Treatment of cancers identified by biopsy may include subsequent removal of tissue surrounding the biopsy site, leaving an enlarged cavity in the patient&#39;s body. Cancerous tissue is often treated by application of radiation, by chemotherapy, or by thermal treatment (e.g., local heating, cryogenic therapy, and other treatments to heat, cool, or freeze tissue). 
     Cancer treatment may be directed to a natural cavity, or to a cavity in a patient&#39;s body from which tissue has been removed, typically following removal of cancerous tissue during a biopsy or surgical procedure. For example, U.S. Pat. No. 5,429,582 to Williams, U.S. Pat. No. 5,913,813 to Williams et al., U.S. Pat. No. 5,931,774 to Williams et al., U.S. Pat. No. 6,022,308 to Williams, U.S. Pat. No. 6,083,148 to Williams, and U.S. Pat. No. 6,413,204 to Winkler et al., the disclosures of which are all hereby incorporated by reference in their entireties, describe devices for implantation into a cavity resulting from the removal of cancerous tissue which can be used to deliver cancer treatments to surrounding tissue. One form of radiation treatment used to treat cancer near a body cavity remaining following removal of tissue is “brachytherapy” in which a source of radiation is placed near to the site to be treated. 
     Williams and coworkers describe implantable devices for treating tissue surrounding a cavity left by surgical removal of cancerous or other tissue that includes an inflatable balloon constructed for placement in the cavity. Such devices may be used to apply one or more of radiation therapy, chemotherapy, and thermal therapy to the tissue surrounding the cavity from which the tissue was removed. The balloon may be filled with a treatment fluid delivered via a conduit from a receptacle, syringe, or other means, or may receive a solid radiation source placed within the balloon. Thus, radiation treatment may be applied to tissue adjacent the balloon by placing radioactive material such as radioactive “seeds” within the balloon, or by filling the balloon with a liquid or slurry containing radioactive material. Multiple treatments may be applied simultaneously. For example, radioactive seeds may be placed within the balloon effective to irradiate tissue surrounding the balloon, and the balloon filled with a hot fluid at the same time to provide thermal treatment. After a suitable time, the hot fluid and/or the radioactive seeds may be removed. Such treatments, combined or otherwise, may be repeated if desired. 
     For example, a “MammoSite® Radiation Therapy System” (MammoSite® RTS, Proxima Therapeutics, Inc., Alpharetta, Ga. 30005 USA) includes a balloon catheter with a radiation source that can be placed within a tumor resection cavity in a breast after a lumpectomy. It can deliver a prescribed dose of radiation from inside 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 may also be used with a balloon catheter placed within a body cavity (e.g., Iotrex®, Proxima Therapeutics, Inc.). The radiation source may be removed following each treatment session, or may remain in place as long as the balloon remains within the body cavity. Inflatable treatment delivery devices and systems, such as the MammoSite® RTS and similar devices and systems (e.g., GliaSite® RTS (Proxima Therapeutics, Inc.)), are useful to treat cancer in tissue adjacent a body cavity. 
     However, radiation, chemotherapy, thermal treatment, and other cancer treatments often have deleterious effects on healthy tissue in addition to the desired effects on cancerous tissue. In such treatments, care must be taken to direct the maximum treatment effects to diseased tissue while minimizing its delivery or effects on healthy tissue. For example, radiation treatment may be most effective when all surrounding tissue regions receive the same dose of radiation, and where the radiation dosage received by more distant tissue is as small and as uniform as possible. However, tissue cavities typically are not uniform or regular in their sizes and shapes, so that differences in dosages applied to different regions of surrounding tissue, including “hot spots” and regions of relatively low dosage, often result from radiation treatment. 
     Thus, there is need in the art for improved devices and methods for delivering cancer treatment to a cavity site within a patient&#39;s body. 
     SUMMARY OF THE INVENTION 
     The invention provides assemblies, devices, systems, and methods for treating tissue adjacent a body cavity, such as a cavity formed by the removal of tissue from a patient. In methods and devices having features of the invention, vacuum is applied effective to draw tissue towards a treatment assembly placed within the body cavity. Assemblies and devices embodying features of the invention include a vacuum delivery element configured to apply a vacuum. A vacuum delivery element may include a vacuum conduit, and may further include a vacuum port. A vacuum delivery element may be configured to at least partially surround or enclose a treatment assembly. A treatment assembly may be configured to deliver a treatment, such as radiation therapy, chemotherapy, thermal therapy, or other treatment, to tissue adjacent 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 may include an inflatable balloon, which may be disposed at least in part around a treatment delivery element. 
     Assemblies and devices embodying features of the invention may include a vacuum delivery element such as a sheath or a balloon configured to provide vacuum effective to apply suction to tissue adjacent the assemblies and devices. Vacuum delivery elements are preferably configured to apply suction to tissue adjacent a treatment delivery assemblies, such as an inflatable treatment delivery device. Suction is effective to draw surrounding tissue close to the surface of a treatment assembly, or to a vacuum delivery element (such as a sheath or balloon) at least partially surrounding or enclosing a treatment assembly, so as to shape the tissue lining the body cavity for optimal treatment. Treatment may be by, e.g., radiation therapy, chemotherapy, thermal therapy, or other treatment modality supplied by the device. A treatment assembly may include an inflatable treatment assembly such as an inner balloon assembly configured to be at least partly enclosed by a vacuum delivery element such as a sheath or balloon. A sheath may be configured to at least partly enclose a balloon temporarily, following placement over or around an inner balloon. A balloon may be configured to at least partly enclose a balloon permanently following placement over or around an inner balloon. 
     Devices may further include an enclosure assembly (which may comprise a sheath assembly or a balloon assembly) comprising a vacuum conduit and a fluid-permeable enclosure wall (e.g., a sheath wall or a balloon wall) configured to partly or completely enclose an inner balloon assembly. Such an enclosure assembly may be effective to provide vacuum and a vacuum path to an intermediate space outside the inner balloon assembly. An intermediate space may include a space disposed between the inner balloon assembly and a sheath assembly or an outer balloon assembly. The enclosure assembly is preferably operatively connected to a vacuum conduit effective to provide vacuum to the intermediate space. Systems having features of the invention include such devices and further include a vacuum source configured to operatively connect with the vacuum conduit. In embodiments of devices having features of the invention, a fluid-permeable enclosure wall may have a hole or multiple holes configured to allow passage of fluid, may be made with a fluid-permeable material, such as a fluid-permeable woven material, or may be otherwise fluid-permeable. The space between the inner balloon and the enclosure may be prevented from collapse, even in the presence of suction from a vacuum delivered via the vacuum conduit, by separation elements disposed on the inner balloon wall, or on the enclosure wall, or both. In alternative embodiments, separation elements disposed within an intermediate space may be independent of both the inner balloon wall and the enclosure wall. 
     An embodiment of a device for treating tissue adjacent a body cavity having features of the invention further comprises an inner balloon assembly, which may include or be operatively connected with an inflation conduit configured to allow passage of a fluid. Devices may also have an inner balloon comprising a distensible inner balloon wall defining an internal lumen. Such an inner balloon may be operatively connected to an inflation conduit so as to allow for passage of fluid through an inflation conduit and into the internal lumen so as to inflate the inner 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 devices and systems having features of the invention, an enclosure wall comprises a polymer, such as biocompatible polymer, preferably a radiation-resistant polymer. Suitable polymers include polyolefins such as polyethylene and polypropylene, polyurethanes, polyester, polyvinylchloride, polystyrene, thermoplastic polymers such as C-Flex® (Consolidated Polymer Technologies, Inc., Clearwater Fla. 33762), block polymers such as Kraton™ (Kraton Polymers, Houston Tex. 77208), an ionomer such as Surlyn® (Dupont, Wilmington Del. 19880), nylon, latex rubber, and silicon rubber (e.g., SILASTIC™, Dow Corning, Midland, Mich.). 
     Devices and systems having features of the invention include inner balloon assemblies configured to enclose a treatment material, such as radioactive material, chemotherapeutic agents, and thermal treatment materials (e.g., materials having a temperature greater than about 37° C.). 
     The invention further provides methods for treating tissue adjacent a body cavity, comprising contacting tissue adjacent a body cavity with a sheath or an outer balloon having a fluid-permeable wall of a device having features of the invention; and applying a vacuum effective to enhance the contact between the fluid-permeable wall and the tissue. Further methods may include delivering inflation fluid to an inner balloon lumen via an inflation conduit to inflate a distensible balloon. In embodiments of the methods of the invention, the inner balloon assembly comprises a treatment assembly such as a Mammosite RTS or similar inflatable treatment delivery device. Methods may include placing a treatment material within the device, and may further include replacing the treatment material. 
     Body cavities are typically not uniform in size or regular in shape. Devices, systems and methods having features of the invention utilize suction to draw tissue against the device surface within a body cavity, insuring good contact between the device and body tissue and providing control over the spacing between tissue and the device, including control over the distance from the treatment material contained within the devices. Tissue lining a body cavity that is held close to, or in contact with, devices having features of the invention forms a uniform and controlled surface, unlike tissue lining a body cavity in which a prior art treatment device has been merely inserted, but which does not urge tissue into a desired orientation and position. The control over the distance, spacing, and amount of tissue contact provided by devices, systems and methods of the present invention offer the advantages of improved treatment tissue adjacent a body cavity. Such improvements may include more uniform dosing, reduction of “hot spots,” shorter treatments due greater correlation between desired and actual dosages, and reduction in the number of locations receiving inadequate dosages. 
     The invention, in one form thereof, is directed to a catheter assembly for delivering a radiation source into a body cavity. The catheter assembly includes a catheter shaft having a distal end and a proximal end. An inflatable balloon is coupled to the catheter shaft between the distal end and the proximal end. A dose delivery lumen extends along the catheter shaft between the proximal end and the distal end. The dose delivery lumen is configured to receive the radiation source. A radioabsorptive portion is surrounded by the inflatable balloon. 
     The invention, in another form thereof, is directed to catheter assembly for delivering a radiation source into a body cavity. The catheter assembly includes a catheter shaft having a distal end and a proximal end. An inflatable balloon is coupled to the catheter shaft between the distal end and the proximal end. A dose delivery lumen extends between the inflatable balloon and the proximal end of the catheter shaft. A vent system includes one or more vents positioned along an outer surface of the inflatable balloon, and one or more vent lumens extending between the proximal end of the catheter shaft and the one or more vents. 
     The invention, in another form thereof, is directed to catheter assembly for delivering a radiation source into a body cavity. The catheter assembly includes an elongate shaft which has a proximal shaft portion, a distal shaft portion and a treatment location in the distal portion. A cavity filling member is located on a distal shaft portion surrounding the treatment location. The cavity filling member has an exterior surface. The cavity filling member is configured to at least partially fill the body cavity. At least one spacing member extends from the exterior surface of the cavity filling member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is partially cut-away perspective view of a system embodying features of the invention shown configured to deliver a treatment within a cavity in a patient&#39;s body tissue while providing vacuum effective to urge tissue into contact with an outer balloon surface. 
         FIG. 2  is a longitudinal cross-sectional view of the system of  FIG. 1  taken along line  2 - 2 . 
         FIG. 3  is a transverse cross-sectional-view of the system of  FIG. 1  taken along line  3 - 3 . 
         FIG. 4A  is a cross-sectional view of a system of  FIG. 1  showing a pie-shaped section of balloon walls between lines  4 - 4  for an embodiment in which an outer wall has stand-offs. 
         FIG. 4B  is a cross-sectional view of the system of  FIG. 1  showing a pie-shaped section of balloon walls between lines  4 - 4  for an embodiment in which an inner wall has stand-offs. 
         FIG. 5A  shows a perspective view of a system embodying features of the invention in which an outer balloon assembly, in the form of a sheath, is being fitted over an inner balloon assembly. 
         FIG. 5B  shows a cross-sectional view of the assembled outer and inner balloon assemblies of  FIG. 5A  following placement into a cavity within a breast of a patient and before inflation of the inner balloon assembly. 
         FIG. 5C  shows a cross-sectional view of the assembled outer and inner balloon assemblies of  FIG. 5A  following inflation of the inner balloon assembly. 
         FIG. 5D  shows a cross-sectional view of the assembled outer and inner balloon assemblies of  FIG. 5A  following application of vacuum to the lumen separating the inner balloon assembly and the outer balloon assembly, and after placement of a radioactive assembly within the inner balloon assembly. 
         FIG. 6A  is perspective view of a system embodying features of the invention including a vacuum delivery element configured to partly enclose an inner balloon assembly. 
         FIG. 6B  is a cross-sectional view of the system of  FIG. 6A  taken along line  6 B- 6 B. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides devices and methods for delivering a treatment, such as a cancer treatment, into a cavity within the body of an animal. For example, devices and methods having features of the invention may be used to deliver treatments into a biopsy site or into a cavity left after removal of cancerous tissue from within the body of a human patient. Vacuum is applied to tissue to enhance contact between a treatment delivery assembly within a body cavity and tissue surrounding the body cavity. A vacuum path around the treatment assembly is provided by devices, systems and methods embodying features of the invention. Vacuum may be applied to tissue via one, two, or multiple vacuum ports. A vacuum port may be a port in a vacuum delivery conduit, a hole in a sheath or balloon connected to a vacuum delivery conduit. A fluid permeable wall or portion of a fluid permeable wall may be effective to serve as a vacuum port. 
       FIG. 1  is a perspective view of a system  10  embodying features of the invention illustrating a device  12  having an outer balloon  14  enclosing an inner balloon  16  (shown in the cut-away portion of the illustration), a shaft  18  and connector  20 . Outer balloon  14  comprises a sheath assembly around inner balloon  16 . Outer balloon  14  is thus an example of an enclosure assembly, and forms an enclosure wall around inner balloon  16 . Outer balloon  14  comprises at least in part a fluid permeable wall; as illustrated in  FIG. 1 , outer balloon  14  has holes  22  allowing fluid permeation into and out of balloon  14 . In alternative embodiments, an outer balloon  14  may be made of woven or otherwise substantially continuous materials that are fluid permeable. In further embodiments, an enclosure wall or assembly such as an outer balloon may comprise a net, mesh, framework, or other discontinuous structure. Holes  22  (or fluid permeable material) allow fluids to pass through outer balloon  14  into intermediate space  24  disposed outside inner balloon  16 . Intermediate space  24  provides a vacuum path adjacent inner balloon  16 . Where at least a portion of outer balloon  14  is disposed adjacent inner balloon  16 , intermediate space  24  is disposed 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  FIG. 2 , a treatment material  30  may be permanently or transiently disposed within delivery shaft  28 . A probe  32  configured to move within delivery shaft  28  may be used to position treatment material  30 , including to place treatment material  30  into and to retrieve placement material  30  from, within delivery shaft  28 . A vacuum conduit  34  may be part of, or may be contained within, a shaft  18  and operatively connected to intermediate space  24 . Shaft  18  may also include or contain an inflation conduit  36  configured to allow passage of inflation fluid into inner lumen  26 . Passage of inflation fluid into inner lumen  26  is effective to inflate inner balloon  16 . Inflation fluid may be any suitable fluid, either a gas or a liquid, and is typically inert. Inflation fluid, where a gas, may be, e.g., air, nitrogen, carbon dioxide or other gas. Inflation fluid, where a liquid, may be water, saline, mineral oil, or other liquid. In some embodiments, an inflation fluid may be effective to absorb radiation to, for example, moderate or adjust a dosage of radiation delivered to a patient&#39;s tissue from radioactive treatment material  30  contained within a delivery shaft  28 . 
     Vacuum applied to intermediate space  24  is effective to deliver a treatment within a body cavity  38  within a patient&#39;s body effective to urge surrounding tissue into contact with at least a portion of the surface of the outer balloon  14 . 
     The outer balloon  14  shown in  FIGS. 1-5  is illustrated as a balloon that is configured to permanently or semi-permanently enclose inner balloon  16  or inner balloon assembly. Such an enclosure may be partial or complete. It will be understood that the outer surface of a device and of a system embodying features of the invention may also be a sheath  50  configured for deployment over and around an inner balloon assembly  14 . In further embodiments, an enclosure may be, e.g. a net, mesh, framework, or other discontinuous structure. 
       FIG. 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 , an inner balloon  16 , and an outer balloon  14  or sheath  50 .  FIG. 2  includes cross-sectional views of shaft  18  including views of delivery shaft  28 , vacuum conduit  34  and inflation conduit  36 .  FIG. 3  is a transverse cross-sectional view of the system of  FIG. 1  taken along line  3 - 3  showing outer balloon  14  and holes  22  therethrough, inner balloon  16  disposed within outer balloon  14 , delivery shaft  28  and probe  32 . 
       FIGS. 4A and 4B  show portions of outer balloon  14  and inner balloon  16  as indicated in  FIG. 1 , including intermediate space  24  and spacers  40  which serve as separation elements effective to maintain patency of intermediate space  24  even under the influence of vacuum supplied via vacuum conduit  34 . Spacers  40  may be part of outer balloon  14 , or of inner balloon  16 , or both. A spacer  40  may be a bump, knob, ridge, or other feature extending inwardly from an inner surface  42  of outer balloon  14 , or extending outwardly from an outer surface  44  of outer balloon  14 . In addition, or alternatively, a spacer  40  may be an object that is placed within intermediate space  24  and is separate from outer balloon  14  and inner balloon  16 . For example, as shown in  FIGS. 4A and 4B , spacers  40  may be stand-offs extending from an inner surface  42  of outer balloon  14  and from an outer surface  44  of outer balloon  14 . 
       FIGS. 5A-5D  illustrate the fitting of an outer balloon assembly  46  (including an outer balloon in the form of a sheath  50 ), over an inner balloon assembly  48  including an inner balloon  16 .  FIG. 5B  shows the assembled outer  46  and inner  48  balloon assemblies of  FIG. 6A  following placement into a cavity  38  within a breast  52  of a patient and before inflation of the inner balloon assembly  48 . In  FIG. 5C , the inner balloon assembly  48  has been inflated by passage of inflation fluid through inflation conduit  36 , pressing some parts of the outer surface  54  outer balloon assembly  46  into contact with portions of the inner surface  56  of body cavity  38 . Note, however, that since most cavities  38  have irregular inner surfaces  56 , there will typically be poor and intermittent contact between outer surface  54  of sheath  50  (or outer balloon  14  in alternative embodiments) and inner surface  56  of cavity  38 , as shown in  FIG. 5C . 
       FIG. 5D  shows the assembled outer  46  and inner  48  balloon assemblies of  FIG. 5A  following application of vacuum via vacuum conduit  34  to the intermediate space  24  separating the inner balloon  16  and the sheath  50  (outer balloon  14 ). Treatment material  30  is in place within delivery shaft  28 . Note that inner surface  56  of cavity  38  has been pulled into intimate contact with outer surface  54  of sheath  50 . Such intimate contact configures inner surface  56  into 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 proper positioning of adjacent tissue to provide proper irradiation. Irradiation levels may vary widely where the adjacent tissue of tissue cavity  38  is at different, irregular, or improper distances from a radiation source. Application of vacuum effective to draw tissue into better contact with device  12 , e.g., into better contact with outer surface  54  of sheath  50 , is effective to improve the delivery of radiation treatment from a radioactive treatment material  30 . 
       FIG. 6A  illustrates a system embodying features of the invention including a vacuum delivery element comprising an enclosure  60  having ribs  62  configured to partly enclose an inner balloon assembly  48 . Vacuum is delivered to intermediate space  24  via vacuum ports  64  operatively connected to vacuum conduit  34 . As shown in cross-section in  FIG. 6B , ribs  62  serve as separation elements effective to provide vacuum paths in the intermediate space  24  between tissue surface  56  and outer surface  44  of inner balloon assembly  48 . 
     Methods for treating tissue adjacent a body cavity  38  include methods for delivering a treatment to tissue adjacent a device  12  embodying features of the invention. For example, a method of treating tissue adjacent a body cavity  38  includes contacting tissue adjacent the body cavity  38  with a sheath  50  or an outer balloon  14 , and applying a vacuum via vacuum conduit  34 . The vacuum may be effective to draw adjacent tissue towards and into contact with a sheath  50  or an outer balloon  14 , and so enhance the contact between the outer wall  54  and the tissue. Delivery of inflation fluid to an inner balloon  16  via an inflation conduit  36  to inflate inner balloon  16  is effective to enhance contact with adjacent tissue as well, serving to bring outer balloon  14  or sheath  50  closer to tissue than it would be in the absence of inflation of inner balloon  16 . In preferred embodiments, the inner balloon assembly  48  comprises an inflatable treatment delivery device such as a Mammosite RTS (Proxima Therapeutics, Inc., Alpharetta, Ga. 30005) or similar device. 
     Methods further include placing a treatment material  30 , such as a radiation source, within the device (e.g., by placement within a delivery shaft  28 ). A radiation source, such as a solid radiation source (e.g., a brachytherapy seeds) may be advanced into a delivery shaft  28  with a probe  32  or by other means. Other solid treatment materials  30  may similarly be advanced into a delivery shaft  28  with a probe  32  or by other means. A liquid radiation source (e.g., Iotrex®, Proxima Therapeutics, Inc., Alpharetta, Ga.) may be advanced into a delivery shaft  28  by fluid flow, under the influence of gravity, pressure applied by a syringe or other pressure source, or other means for delivering fluid into a space. Similarly, hot liquids and other liquid treatment materials  30  may be introduced into a delivery shaft  28  or an inner balloon  16  (via inflation conduit  36 ) under the influence of gravity, pressure applied by a syringe or other pressure source, or other means for delivering fluid into a space. 
     Some treatment regimens may include periodic or episodic treatment, in which radiation or other treatment is applied for a treatment period, and then the treatment is stopped for a recovery period. Such periodic or episodic treatments may be repeated, so that treatment is applied during a first treatment period, stopped during a first recovery period, and then treatment is re-applied for a second treatment period. Further treatment periods and recovery periods may also be used as necessary. Thus, methods may further include removal of a radiation source or other treatment material  30  from within a delivery shaft  28 , and may further include replacing the treatment material  30 . 
     Although a cavity  38  is typically an artificial cavity remaining after removal of tissue at biopsy, surgery, or other medical procedure, a body cavity may be a natural body cavity. For example, devices  12  may be inserted into a bladder for the treatment of bladder cancer. Application of suction is effective to enhance contact with a device  12  in such an example as well. Such enhanced contact may be effective to improve the delivery of radiation or other treatment, and may be effective to avoid “hot spots” (tissue regions receiving more radiation than is received by neighboring tissue regions) and is one of the important advantages provided by the present invention. 
     Treatment material  30  may include a chemotherapy agent effective to treat cancer or other disease condition of tissue surrounding a body cavity  38 . In preferred embodiments, treatment material  30  includes a radiation source configured to delivery radiation to tissue adjacent a device  12 . 
     Thus, treatment material  30  may include a radiation source which may be solid or liquid. A liquid radiation source may include, for example, a liquid containing a radioactive iodine isotope (e.g.,  125 I or  131 I), a slurry of a solid isotope, e.g.  198 AU,  90 Y,  169 Yb, or a gel containing a radioactive isotope. Liquid radiation sources are commercially available (e.g., from Iotrex®, Proxima Therapeutics, Inc., Alpharetta, 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 the 3M Company of St. Paul, Minn. A solid radioactive source can either be preloaded into a device  12  at the time of manufacture or may be loaded into the device  12  after placement into body cavity  38  of a distal portion of the device  12 . Such distal portion preferably includes the outer balloon  14 , inner balloon  16 , and at least a portion of delivery shaft  28 . Such a solid radioactive core configuration offers the advantage in that it allows a wider range of radionuclides than if one is limited to liquids. Solid radionuclides suitable for use with a delivery device embodying features of the present invention are currently generally available as brachytherapy radiation sources (e.g., I-Plant™, Med-Tec, Orange City Iowa). 
     In general, the amount of radiation desired by the physician is a certain minimum amount that is delivered to a site about 0-3 cm away from the wall of the body cavity  38  (e.g., from where a tumor has been excised). Vacuum applied to intermediate space  24  effects good contact between tissue surrounding body cavity  38  and the wall of the outer balloon  14  or sheath  50 , promoting effective treatment delivery, such as delivery of 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 over-exposure to tissue at or near the reservoir wall. It is well known that the absorbed dose rate at a point exterior to a radioactive source is inversely proportional to the square of the distance between the radiation source and the target point. Thus, it is possible that the radiation dosage delivered to adjacent tissue may differ from that delivered to tissue disposed at more distal locations. In some instances, penetration of radiation to locations far from a device  12  is not desired. For example, in treating cancers such as bladder cancer, where the neoplastic tissue is generally located on the bladder surface, deep penetration is unnecessary and to be avoided. 
     An inflation fluid may also be a radiation absorbing fluid. For example, an inflation fluid may be an X-ray contrast agent as used in angiography, such as a Barium salt (e.g., barium sulfate), water, saline or other such fluid. A radiation-absorbing inflation fluid, which will surround a radiation source placed within delivery shaft  28 , serves to moderate and control the delivery of radiation from the radiation source to surrounding tissue. Such moderation and control that is obtained with a radiation-absorbing inflation fluid may aid in avoiding the delivery of an excessive amount of radiation to some portions of the surrounding tissue. 
     Thus, in the absence of such a radiation-absorbing inflation fluid, it is possible in some instances that a radiation source sufficient to provide an effective dose at distances removed from a device  12 , would expose tissue that is directly adjacent the wall of the outer balloon  14  or sheath  50  to an excessive radiation dose. Such excessive exposure to such tissue near to the device  12  may result in necrosis of healthy tissue necrosis. 
     Alternatively, an inflation fluid may contain radioactive elements, either as a liquid or slurry, 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 volume of the inner balloon  16 . In such embodiments, an inflation fluid thus itself serves as a radiation source, thereby providing well-controlled amounts of radiation to surrounding tissue while minimizing irregularities in the dosages delivered to particular locations. 
     In embodiments of the invention in which an inflation fluid includes a radiation source, a delivery shaft  28  may contain a radiation absorptive material, so that, for example, less volume of radioactive material is required than if the entire volume of a device  12  were filled with radioactive material. Such a configuration may be advantageous where a profile exhibiting higher intensity at a tissue surface with lesser penetration is desired. Moreover, the outer balloon  14  need not be spherical, yet a uniform profile of radiation delivery is obtainable. Experiments reported in Williams U.S. Pat. No. 5,918,813 are described as showing that a steeper radial absorbed source gradient can be obtained using a radiation attenuation fluid in an inner chamber of a similar radiation deliver device than otherwise obtains with a device having only a single distensible chamber (as described in Williams U.S. Pat. No. 5,429,582).