Radiation applicator and method of radiating tissue

Abstract

A dipole microwave applicator emits microwave radiation into tissue to be treated. The applicator is formed from a thin coax cable having an inner conductor surrounded by an insulator, which is surrounded by an outer conductor. A portion of the inner conductor extends beyond the insulator and the outer conductor. A ferrule at the end of the outer conductor has a step and a sleeve that surrounds a portion of the extended inner conductor. A tuning washer is attached to the end of the extended inner conductor. A dielectric tip encloses the tuning washer, the extended inner conductor, and the sleeve of the ferrule. The sleeve of the ferrule and the extended inner conductor operate as the two arms of the dipole microwave antenna. The tuning washer faces the step in the ferrule, and is sized and shaped to cooperate with the step in balancing and tuning the applicator.

1 . A dipole microwave applicator for emitting microwave radiation into tissue, the assembly comprising: 
 an outer conductor having an end;    an inner conductor disposed within the outer conductor, and including a section that extends outwardly beyond the end of the outer conductor;    a ferrule disposed at the end of the outer conductor, and having a sleeve portion that surrounds a portion of the outwardly extending section of the inner conductor; and    a dielectric tip surrounding the sleeve portion of the ferrule and the outwardly extending section of the inner conductor,    whereby the sleeve portion of the ferrule and at least a portion of the outwardly  1 l extending section of the inner conductor operate as corresponding arms of the dipole microwave applicator.    
     
     
         2 . The dipole microwave applicator of  claim 1  further comprising a dielectric spacer disposed within the dielectric tip, the dielectric spacer surrounding at least a portion of the inner conductor that extends beyond the sleeve portion of the ferrule.  
     
     
         3 . The dipole microwave applicator of  claim 1  wherein the ferrule has a first end that is attached to the end of the outer conductor.  
     
     
         4 . The dipole microwave applicator of  claim 1  further comprising a tuning element disposed within the dielectric tip, and attached to an end of the inner conductor.  
     
     
         5 . The dipole microwave applicator of  claim 4  wherein 
 the ferrule further includes a step adjacent to the sleeve portion, and    the tuning element and step cooperate to balance the corresponding arms of the dipole microwave applicator.    
     
     
         6 . The dipole microwave applicator of  claim 5  wherein the tuning element is substantially disc shaped.  
     
     
         7 . The dipole microwave applicator of  claim 5  further comprising a rigid sleeve adjacent to the ferrule, and surrounding and spaced from at least a portion of the outer conductor so as to define a space between the outer conductor and the rigid sleeve.  
     
     
         8 . The dipole microwave applicator of  claim 7  wherein one or more holes extend through the rigid sleeve, the one or more holes providing a fluid communication path from the space within the rigid sleeve to an area outside of the rigid sleeve.  
     
     
         9 . The dipole microwave applicator of  claim 1  wherein 
 the ferrule is formed from copper, and    the tip is formed from itrium stabilized zirconia.    
     
     
         10 . The dipole microwave applicator of  claim 8  wherein 
 the sleeve is formed from stainless steel,    the ferrule is formed from copper, and    the tip is formed from itrium stabilized zirconia.    
     
     
         11 . The dipole microwave applicator of  claim 1  wherein microwave energy at a frequency of approximately 2.45 Gigahertz (GHz) and a power level of up to 80 watts is applied to the applicator.  
     
     
         12 . The dipole microwave applicator of claim of  claim 2  further comprising an insulator disposed between the outer conductor and the inner conductor, wherein 
 the spacer abuts an end of the sleeve of the ferrule and the insulator terminates within the sleeve so as to define a gap within the sleeve of the ferrule around the inner conductor.    
     
     
         13 . The dipole microwave applicator of  claim 10  wherein the gap is filled with air.  
     
     
         14 . The dipole microwave applicator of  claim 5  wherein 
 the dielectric tip has open end that abuts the step in the ferrule and a closed end opposite the open end, and    the closed end is configured for one of cutting or piercing tissue.    
     
     
         15 . The dipole microwave applicator of  claim 1  wherein at least one of the dielectric tip and the ferrule is coated with an inner layer of polyimide and an outer layer of paralyne.