Radiation applicator for microwave medical treatment

Abstract

A radiation applicator with a dielectric body ( 2 ) surrounding the antenna The dielectric body ( 2 ) is comprised of three sections ( 3, 4 and 5 ) with different dielectric constants to provide broad-band matching of the applicator to surrounding material. Washers ( 10 ) and ( 11 ) are mounted on the antenna to act as reflectors.

1 . A radiation applicator having one end and an opposite distal end, the radiation applicator comprising: 
 a power input at said one end,    an elongate antenna extending axially of the applicator at said distal end, and    a dielectric body which surrounds the antenna and serves to emit radiation radially of the dielectric body into surrounding material, the dielectric body comprising multiple sections of different dielectric constant which are located axially relative to one another along the antenna.    
     
     
         2 . An applicator as claimed in  claim 1  in which, the dielectric body consists of a second section adapted to emit radiation, and a first section between the second section and the power input, and having a lower dielectric constant than the first section.  
     
     
         3 . An applicator as claimed in  claim 2  in which the dielectric body has an outer section furthest from the power input having a dielectric constant lower than that of the second section.  
     
     
         4 . An applicator as claimed in  claim 3  in which the outer section has a dielectric constant intermediate that of the first and second sections.  
     
     
         5 . An applicator as claimed in  claim 1  in which, the multiple sections are made as separate components and are assembled to abut against one another end-to-end.  
     
     
         6 . An applicator as claimed in  claim 1  in which, a radiation reflector is provided at the interface between two sections of the dielectric body so as to modulate the transmission of radiation and tune the applicator.  
     
     
         7 . An applicator as claimed in  claim 6  in which, a radiation reflector is provided each side of a section which is intended to emit radiation into the surrounding material, a reflector on that side further from the input end having a larger area so as to reflect more energy than the reflector nearer the input end, thereby reducing transmission of radiation to the tip of the applicator.  
     
     
         8 . A radiation applicator having one end and an opposite distal end, the radiation applicator comprising: 
 a power input at said one end,    an elongate antenna extending axially at said distal end for emitting radiation into surrounding material,    a dielectric body which surrounds the antenna, and    a plurality of radiation reflectors located axially along the antenna within the dielectric body to modulate the transmission of radiation, wherein two radiation reflectors are axially spaced apart with an intermediate section of the dielectric body disposed between said two radiation reflectors and intended to emit radiation radially into the surrounding material, the reflector on one side further from the input having a larger area so as to reflect more radiation than the reflector nearer the input end, thereby reducing transmission of radiation to the tip of the applicator.    
     
     
         9 . An applicator as claimed in  claim 6  in which, the reflector is located at an interface between separate sections of the dielectric body and gives structural support to the applicator.  
     
     
         10 . An applicator as claimed in  claim 1  in which an outer end of the dielectric body furthest from the power input is pointed.  
     
     
         11 . An applicator as claimed in  claim 1  in which the power input comprises a coaxial conductor having a central conductor and an outer conductor, and in which the central conductor extends from the outer conductor to form said elongate antenna.  
     
     
         12 . An applicator as claimed in  claim 11  in which the dielectric body has a reduced diameter and which is inserted into an open end of the outer conductor.  
     
     
         13 . A radiation applicator having one end and an opposite distal end, the radiation applicator comprising: 
 a power input at said one end,    an elongate antenna extending axially at said distal end for emitting radiation into surrounding material, and    a dielectric body which surrounds the antenna, wherein the antenna extends through a hole in a section of said dielectric body and through a hole in a radiation reflector attached to an axial end face of said section of dielectric body, and said radiation reflector is attached to the antenna so as to give structural support to the applicator.    
     
     
         14 . A radiation applicator having one end and an opposite distal end, the radiation applicator comprising: 
 a power input at said one end,    an elongate antenna extending axially of the applicator at said distal end, and    a dielectric body which surrounds the antenna and serves to emit radiation radially of the antenna into surrounding material, wherein the dielectric body comprises multiple sections of different dielectric constant which are located axially relative to one another along the antenna.