Method and apparatus for optical inhibition of photodynamic therapy

Abstract

A system and method are provided for preventing damage to the epidermis or other epithelial or non-target tissue during photodynamic therapy treatment. For example, an inhibiting radiation can be used to control formation of a photosensitizer from a precursor photosensitizer in the epidermis or epithelial tissue. Subsequent application of a treatment radiation can activate the photosensitizer to damage or destroy target sites while the non-target tissue remains substantially unaffected.

1 - 20 . (canceled) 
     
     
         21 . An apparatus for applying radiation to an anatomical structure, comprising:
 a first radiation source configured to provide radiation in a first wavelength range to the anatomical structure to reduce or eliminate a presence or an effectiveness of a photosensitizer within a first region of the anatomical structure; and   a second radiation source configured to provide a radiation in a second wavelength range to the anatomical structure, following application of the radiation in the first wavelength range to interact with the photosensitizer to damage at least a portion of a second region of the anatomical structure,   wherein the radiation in the first wavelength range is shorter than the radiation in the second wavelength range, and   wherein the first region is substantially unaffected by the radiation in the second wavelength range.   
     
     
         22 . The apparatus of  claim 21 , further comprising a controller arrangement configured to control at least one parameter associated with the first radiation source, wherein the at least one parameter includes at least one of a wavelength, a fluence, an irradiance, a pulse rate, or a duration of application. 
     
     
         23 . The apparatus of  claim 22 , wherein the controller arrangement is further configured to control an angle of incidence of the first radiation to affect a depth of penetration of the first radiation into the anatomical structure. 
     
     
         24 . The apparatus of  claim 21 , wherein the anatomical structure comprises skin tissue. 
     
     
         25 . The apparatus of  claim 21 , wherein a precursor of the photosensitizer comprises at least one of aminolevulinic acid (ALA), a derivative of ALA, a methl-ester of ALA, and an amide of ALA, an ester of ALA, and a salt of ALA. 
     
     
         26 . The apparatus of  claim 21 , wherein the radiation in the first wavelength range has a wavelength that is between about 320 nm and about 850 nm. 
     
     
         27 . The apparatus of  claim 26 , wherein the radiation in the first wavelength range has a wavelength that is between about 320 nm and about 450 nm. 
     
     
         28 . The apparatus of  claim 21 , wherein the radiation in the first wavelength range is applied at an irradiance that is between about 0.01 mW/cm 2  and about 30 mW/cm 2 . 
     
     
         29 . The apparatus of  claim 21 , wherein the radiation in the first wavelength range is applied at a fluence that is between about 1 J/cm 2  and about 100 J/cm 2 . 
     
     
         30 . The apparatus of  claim 21 , wherein the apparatus is configured to provide the radiation in the first wavelength range at a total fluence that is smaller than a total fluence of the radiation in the second wavelength range. 
     
     
         31 . The apparatus of  claim 21 , wherein the radiation in the second wavelength range has a wavelength that is between about 380 nm and about 700 nm. 
     
     
         32 . The apparatus of  claim 21 , wherein the at least one parameter associated with the first radiation source is selected to photobleach the photosensitizer within the first region of the anatomical structure. 
     
     
         33 . The apparatus of  claim 32 , wherein the radiation in the second wavelength range is configured to interact with the photosensitizer located in the second region to produce a phototoxic species so as to damage at least a portion of the second region, and wherein the first region is substantially unaffected by the radiation in the second wavelength range. 
     
     
         34 . The apparatus of  claim 32 , wherein the photosensitizer includes at least one of a porphyrin, chlorin, porphycene, purpurin, phthalocyanine, naphthalocyanine, bacteriochlorin, benzophenothiazine, tetracycline, methylene blue, and hypericin. 
     
     
         35 . An apparatus for applying radiation to an anatomical structure, comprising:
 a first radiation source configured to provide radiation in a first wavelength range to the anatomical structure to photobleach a photosensitizer within a first region of the anatomical structure; and   a second radiation source configured to provide radiation in a second wavelength range to the anatomical structure, following application of the radiation in the first wavelength range to interact with the photosensitizer located in a second region of the anatomical structure to produce a phototoxic species so as to damage at least a portion of the second region,   wherein the radiation in the first wavelength range is shorter than the radiation in the second wavelength range, and   wherein the first region is substantially unaffected by the radiation in the second wavelength range.   
     
     
         36 . The apparatus of  claim 35 , wherein the radiation in the first wavelength range has a wavelength that is between about 320 nm and about 450 nm. 
     
     
         37 . The apparatus of  claims 36 , wherein the radiation in the second wavelength range has a wavelength that is between about 470 nm and about 700 nm. 
     
     
         38 . A computer-readable medium, comprising:
 a first set of executable instructions which, when executed by a processing arrangement, configure the processing arrangement to control a first radiation source to provide a first radiation in a first wavelength range to the anatomical structure, wherein the radiation in the first wavelength range is configured to at least one of reduce or eliminate a formation of presence or effectiveness of a photosensitizer that results from a precursor photosensitizer within a first region of the anatomical structure; and   a second set of executable instructions which, when executed by a processing arrangement, configure the processing arrangement to control a second radiation source to provide a second radiation in a second wavelength range to the anatomical structure after application of the radiation in the first wavelength range, wherein the second radiation in the second wavelength range is configured to interact with the photosensitizer to produce a phototoxic species located in a second region of the anatomical structure so as to damage at least a portion of the second region while, and wherein the first region is substantially unaffected by the second radiation in the second wavelength range,   wherein the radiation in the first wavelength range is shorter than the radiation in the second wavelength range.   
     
     
         39 . The computer-readable medium of  claim 38 , wherein the radiation in the first wavelength range has a wavelength that is between about 320 nm and about 450 nm. 
     
     
         40 . The computer-readable medium of  claim 39 , wherein the radiation in the second wavelength range has a wavelength that is between about 470 nm and about 700 nm.