Intravascular radiation therapy device, and method of use

Abstract

A radiation delivering catheter is positioned away from the walls of the vessel to be treated, e.g. at a stenosis site, so that the radiation flux impacting the walls is more uniform. In one embodiment, one or more balloons are used, and in another, one or more expandable structures. In other embodiments, a radiation source residing within a balloon is shielded from the vessel walls when the balloon is not inflated, but exposes the vessel walls to radiation when the balloon is inflated.

What is claimed is:  
     
         1 . A radiation device for treating a segment of a vessel in a patient, comprising: 
 a catheter for delivering radiation;    a radioactive source in proximity with said radiation catheter;    a noncompliant balloon around said radioactive source;    a lumen within said radiation catheter that is in fluid communication with said noncompliant balloon, permitting inflation and deflation of said noncompliant balloon; and    a compliant balloon that surrounds said noncompliant balloon, wherein said compliant balloon expands as said noncompliant balloon expands to radioactively treat the vascular segment.    
     
     
         2 . The device of  claim 1 , in which said compliant balloon has slits therein, the area of said slits increasing as said compliant balloon expands to more directly expose the vascular segment to radioactive treatment.  
     
     
         3 . The device of  claim 2 , in which said compliant balloon comprises a shielding layer to prevent unwanted radioactive exposure of the surroundings when said compliant balloon is not inflated.  
     
     
         4 . The device of  claim 3 , in which said shielding layer comprises a material selected from the group consisting of platinum and gold.  
     
     
         5 . The device of  claim 1 , further comprising a guidewire within said radiation catheter for directing said radiation catheter through the vessel.  
     
     
         6 . A radiation device for treating a segment of a vessel in a patient, comprising: 
 a catheter for delivering radiation;    a radioactive source in proximity with said radiation catheter;    a balloon around said radioactive source;    a lumen within said radiation catheter that is in fluid communication with said balloon, permitting inflation and deflation of said balloon; and wherein    said balloon has strips of material thereon that substantially shield the surroundings from unwanted radioactive exposure when said balloon is not inflated, the area between said strips increasing as said balloon expands to more directly expose the vascular segment to radioactive treatment.    
     
     
         7 . The device of  claim 6 , further comprising a guidewire within said radiation catheter for directing said radiation catheter through the vessel.  
     
     
         8 . A self-positioning radiation device for treating a segment of a vessel in a patient, comprising: 
 a catheter for delivering radiation;    at least one expandable structure for securing said radiation catheter within the vessel; and    a radioactive source for treating the vascular segment, said radioactive source in proximity with said radiation catheter.    
     
     
         9 . The device of  claim 8 , in which said expandable structure is self-expanding.  
     
     
         10 . The device of  claim 9 , in which said self-expanding expandable structure is attached to an indentation on said radiation catheter.  
     
     
         11 . The device of  claim 8 , in which said expandable structure is braided and attached to a pull wire that deploys said at least one expandable structure.  
     
     
         12 . The device of  claim 8 , in which said expandable structure is attached to said guidewire.  
     
     
         13 . The device of  claim 8 , in which the radial extent of said expandable structure when said expandable structure is deployed around said radiation catheter is less than 360 degrees, permitting perfusion around said expandable structure and reducing the risk of clot formation within said expandable structure.  
     
     
         14 . The device of  claim 8 , in which one expandable structure is located distal to the vascular segment.  
     
     
         15 . The device of  claim 8 , further comprising a guidewire within said radiation catheter for directing said radiation catheter through the vessel.  
     
     
         16 . The device of  claim 8 , comprising two expandable structures.  
     
     
         17 . The device of  claim 16 , further comprising a sheath for expanding and compressing said expandable structures.  
     
     
         18 . The device of  claim 16 , further comprising a proximal catheter that acts as a sheath for expanding and compressing one of said expandable structures.  
     
     
         19 . The device of  claim 18 , in which one of said expandable structures is attached to said proximal catheter and the other of said expandable structures is attached to said radiation catheter.  
     
     
         20 . The device of  claim 16 , in which both of said expandable structures are attached to said radiation catheter.  
     
     
         21 . The device of  claim 20 , further comprising a sheath for expanding and compressing both of said expandable structures.  
     
     
         22 . The device of  claim 8 , further comprising: 
 an injection lumen within said radiation catheter for accepting fluid that contains radioactive carriers, said injection lumen having a constriction therein beyond which said carriers cannot advance, said constriction positioned so that said carriers effectively treat the vascular segment; and    a vent lumen, wherein said injection lumen and said vent lumen are in fluid communication with each other, permitting said carriers to be injected into said injection lumen by passing said fluid from said injection lumen into said vent lumen, said carriers being retrieved by passing said fluid from said vent lumen into said injection lumen.    
     
     
         23 . A method of treating a segment in a vessel, comprising: 
 inserting a catheter into the vessel;    inserting a plurality of balloons into the vessel, wherein at least two of the balloons are independently inflatable;    inflating at least two of the independently inflatable balloons to position the catheter away from the walls of the vessel; and    exposing the vascular segment to radiation treatment.    
     
     
         24 . The method of  claim 23 , further comprising: 
 deflating the inflated balloons after the treatment; and    removing the balloons and the catheter from the vessel.    
     
     
         25 . The method of  claim 23 , in which said exposing of the vascular segment to radiation comprises injecting radioactive carriers through a lumen in the catheter.  
     
     
         26 . A method of treating a segment in a vessel, comprising: 
 inserting a first balloon into the vessel;    placing the balloon near the vascular segment to be treated; and    expanding the balloon to expose the vascular segment to radiation that is concentrated along an axis centered within the balloon.    
     
     
         27 . The method of  claim 26 , in which the balloon is attached to a catheter.  
     
     
         28 . The method of  claim 26 , in which the balloon has radiopaque strips thereon for shielding the surroundings from radiation when the balloon is not inflated.  
     
     
         29 . The method of  claim 28 , wherein 
 the first balloon has slits between the strips; and    said expanding the first balloon comprises inflating a second balloon to expand the first balloon, the second balloon being in contact with and located within the first balloon.    
     
     
         30 . A method of treating a segment in a vessel, comprising: 
 inserting a catheter into the vessel;    inserting at least one expandable structure into the vessel;    expanding the expandable structure to position the catheter away from the walls of the vessel; and    treating the vascular segment by exposing it to radiation.    
     
     
         31 . The method of  claim 30 , further comprising: 
 compressing the expandable structure after treatment; and    removing the expandable structure and the catheter from the vessel.    
     
     
         32 . The method of  claim 30 , in which said exposing of the vascular segment to radiation comprises injecting radioactive carriers through a lumen in the catheter.  
     
     
         33 . The method of  claim 30 , in which said expanding the expandable structure comprises pulling on a wire.  
     
     
         34 . The method of  claim 30 , in which at least two expandable structures are used to position the catheter.  
     
     
         35 . The method of  claim 34 , in which a plurality of sheaths are used to deploy and compress the expandable structures.  
     
     
         36 . The method of  claim 30 , in which said treating the vascular segment comprises introducing radioactive carriers attached to a wire.  
     
     
         37 . A radiation device for treating a segment of a vessel in a patient, comprising: 
 a catheter;    a guidewire within said catheter for directing said catheter through the vessel; and    a radioactive source fastened directly onto said catheter.    
     
     
         38 . The device of  claim 37 , further comprising a retractable shield that surrounds said radioactive source when the vascular segment is not being treated.  
     
     
         39 . The device of  claim 37 , in which said radioactive source is bonded onto said catheter.