Abstract:
An applicator designed for use with a miniature electronic x-ray source, having a relatively large guide for the electronic source, is modified by an adapter inserted into the source guide to produce a narrower-diameter guide that will receive a standard afterloader that irradiates with isotopes.

Description:
[0001]     This application is a continuation-in-part of application Ser. No. 10/464,140 filed Jun. 18, 2003, which is incorporated by reference herein in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     This invention concerns therapeutic radiation treatment, and especially apparatus for brachytherapy radiation treatment.  
         [0003]     Electronic radiation sources are disclosed in U.S. Pat. No. 6,319,188 as well as in co-pending applications Ser. No. 10/464,140 filed Jun. 18, 2003, Ser. No. 10/371,401 filed Feb. 21, 2003 and Ser. No. 10/397,498 filed Mar. 26, 2003, of Xoft, Inc. These electronic x-ray sources range from about 3 or 4 mm in diameter down to about 1 mm in diameter. Applicators for electronic sources have been proposed, particularly for post-operative brachytherapy of a breast tumor resection cavity, and also for-other tissue treatment. Such an applicator has a shaft with a lumen or guide that receives a catheter device with the electronic x-ray source at or near its tip. This is connected by a high voltage cable back to a controller operated by the surgeon or technician.  
         [0004]     It is desirable to adapt the applicator designed for electronic sources to use with standard afterloaders, in order to provide the versatility of only one type of applicator in a treatment facility, useable with both electronic and isotope x-ray sources.  
       SUMMARY OF THE INVENTION  
       [0005]     In accordance with the current invention, an applicator designed for use with a miniature electronic x-ray source, and having a relatively large channel or guide for the electronic source, is modified by an adapter inserted into the source guide to produce a narrower-diameter guide that will receive a standard afterloader for irradiation with isotopes. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  is an exploded-type view showing, schematically, an applicator intended for use with an electronic x-ray source, having a relatively large internal guide, and an adapter device for insertion into the applicator, to produce a smaller guide lumen that will receive an afterloader carrying an HDR seed or pellet.  
         [0007]      FIG. 2  is a cross section view through the adapter device, showing features of a preferred embodiment. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0008]     In the drawing,  FIG. 1  shows a balloon applicator  10  designed for use with an electronic x-ray source. The applicator  10  includes a balloon  12  and a shaft  14  within which is a central guide or lumen  16  to receive a catheter or probe carrying an electronic radiation source, not shown. Other lumens are included in the shaft  14 , for various purposes, but these are not shown in the drawing. At the proximal end of the applicator are ports  18  and  20  for cooling, suction, and/or other purposes, as well as the central port  22  to receive the radiation source.  
         [0009]     In one typical applicator of Xoft, Inc., the balloon applicator  10  has a service centering lumen  16  with a diameter of about 4 to 6 mm, for breast therapy or other radiation therapy application.  
         [0010]      FIG. 1  shows an adapter  24  according to the invention, for insertion through the center port  22  into the service centering lumen or guide  16  of the applicator. The HDR adapter  24  has just sufficient clearance for entry into the service lumen  16 , and has a smaller center lumen  26 , with a proximal entry  28 , the diameter of this lumen  26  being about  1  mm for an HDR pellet to be inserted, via a standard afterloader (not shown).  
         [0011]     The adapter  24 , which serves to provide a smaller service lumen in the applicator  10 , can be formed of injection molded plastic such as Hytrel, silicone or other biocompatible material. At the proximal end of the adapter is an end piece  30  which may be attached to the elongated adapter shaft  24  or which could be integrally formed by injection molding. This proximal end-piece  30  is configured to nest with the proximal end of the existing applicator device  10 . Preferably some form of positive lock or positive fix is included, such as a snap-in or a thread. There should be a positive visual (and also, optimally, tactile) indication that the adapter is in the right place so that treatment is correct.  
         [0012]     For this purpose  FIG. 2  shows one form of positive position locator, with the adapter shaft  24  shown in cross section. Outer lumens  35  are provided in the adapter shaft  24 , forward of flexible material such as silicone. Three are shown, spaced equilaterally, but more can be provided. Fluid pressure is applied to these lumens  35  after the adapter is inserted fully into the guide  16  of the adapter  10 . This expands the adapter shaft outwardly at the locations of the pressure-receiving lumens  35  to secure the adapter against the inner lumen or guide wall  16  of the balloon applicator  10 . The expansion of the adapter shaft also acts to center the adapter  24 , while securing it in place against axial movement.  
         [0013]     It is also possible, via use of the HDR adapter  24 , to provide verification of dose using dosimeters  36  (three shown in  FIG. 2 ) that are on the outer wall of or embedded in the outer surface of the adapter shaft  24 . These can be wirelessly connected to a treatment point existent to feed back, in real time, dose received at the locations of the dosimeters, thus enabling by extrapolation calculation of the dose delivered at the tissue. This can provide not only verification that treatment was according to plan, but real-time feedback control of the treatment procedure itself, via the treatment planning system. With an HDR source pullback rate or dwell time at each of a series of stepped locations can be changed in real time based on the feedback.  
         [0014]     Note also that the feedback control dosimeters  36  can be located in the applicator shaft  14  of the applicator  10 , or in the balloon  12  of the applicator.  
         [0015]     The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit its scope. Other embodiments and variations to these preferred embodiments will be apparent to those skilled in the art and may be made without departing from the spirit and scope of the invention.