Method and system for optically evaluating proximity to the inferior alveolar nerve in situ

Abstract

A surgical drilling system for determining proximity of a surgical drill bit to an artery during a drilling procedure, including an excitation and/or collection optical channel of a spectral absorption probe, wherein the excitation channel provides light configured for absorption by blood chromophores and the collection channel captures diffused back-scattered light modulated by said artery; a light detector; and a signal processor for determining a distance between the tissue and the probe based on said back-scattered light. A process for determining proximity of a surgical drill bit to an artery during a drilling procedure includes bringing said excitation light near the tissue including the artery; capturing diffused back-scattered light from said tissue; detecting said light modulated by said blood flow dynamics including an oscillating signal related to said periodic change; and processing said light and determining the proximity of the surgical drill bit to the artery.

What is claimed is: 
     
         1 . A surgical drilling system for determining proximity of a surgical drill bit to an artery located within tissue during a drilling procedure, the surgical drilling system comprising:
 at least one of an excitation optical channel and a collection optical channel of a spectral absorption probe, wherein the excitation optical channel provides excitation light to the tissue, the excitation light having a wavelength configured for absorption by blood chromophores;   further wherein the collection optical channel of the spectral absorption probe captures diffused back-scattered light from the tissue including the artery, wherein said diffused back-scattered light is modulated by blood flow dynamics in said artery, said blood flow dynamics being a periodic change in blood volume in said artery due to a cardiac cycle;   a light detector of the spectral absorption probe operatively connected to said collection optical channel for detecting said diffused back-scattered light modulated by blood flow dynamics including an oscillating signal, a frequency of said oscillating signal being related to said periodic change; and   a signal processor of the spectral absorption probe operatively connected to said light detector for determining a distance between the tissue including the artery and the spectral absorption probe based on said diffused back-scattered light using one or more characteristics of the oscillating signal and a value for surrounding tissue attenuation coefficient, further wherein the determined distance is indicative of the proximity of the surgical drill bit to the artery.   
     
     
         2 . The surgical drilling system of  claim 1 , wherein the at least one of the excitation optical channel and the collection optical channel located is included in an optical fiber. 
     
     
         3 . The surgical drilling system of  claim 1 , wherein both of the excitation optical channel and the collection optical channel are located within the surgical drill bit. 
     
     
         4 . The surgical drilling system of  claim 3 , wherein said excitation optical channel and said collection optical channel are each provided in a single multi-clad optical fiber with a fiber core of said multi-clad optical fiber bringing said excitation light near said tissue and at least a first clad of said multi-clad optical fiber capturing said back-scattered light from said tissue. 
     
     
         5 . The surgical drilling system of  claim 2 , further including a rotating surgical drill, wherein the optical fiber is provided in a core of the rotating surgical drill. 
     
     
         6 . The surgical drilling system of  claim 2 , further including a rotating surgical drill, wherein the optical fiber is coupled to the rotating surgical drill. 
     
     
         7 . The surgical drilling system of  claim 5 , wherein the core is provided with an optically transparent seal at a tip of the drill bit to prevent introduction of organic tissue therein. 
     
     
         8 . The surgical drilling system of  claim 1 , wherein one or both of the collection optical channel and the excitation optical channel of the spectral absorption probe are located physically separate from a surgical drill of the surgical drilling system, but remain operatively connected thereto. 
     
     
         9 . A process for determining proximity of a surgical drill bit to an artery located within tissue during a drilling procedure, comprising:
 generating an excitation light by a light source of a probe having a wavelength configured for absorption by blood chromophores;   bringing said excitation light by an excitation channel of the probe near the tissue including the artery;   capturing by a first collection channel of the probe diffused back-scattered light from said tissue including the artery, where said diffused back-scattered light is modulated by blood flow dynamics in said artery, said blood flow dynamics being a periodic change in blood volume in said artery due to a cardiac cycle;   detecting by a first light detector of the probe said diffused back-scattered light modulated by said blood flow dynamics including an oscillating signal, a frequency of said oscillating signal being related to said periodic change; and   
       processing by a digital signal processor of the probe said diffused back-scattered light from said tissue including the artery to determine a first distance between the tissue including the artery and spectral absorption probe, said processing including using one or more characteristics of said oscillating signal and a value for surrounding tissue attenuation coefficient, and determining the proximity of the surgical drill bit to the artery using the determined first distance. 
     
     
         10 . The process according to  claim 9 , further comprising:
 capturing by a second collection channel of the probe low-coherence back-scattered light from said tissue layer and the artery;   performing by a second light detector of the probe interferometry between said excitation light and said low-coherence back-scattered light for providing an interference signal; and   processing by the digital signal processor said interference signal for determining a second distance between the tissue including the artery and the spectral absorption probe, and determining the proximity of the surgical drill bit to the artery using the determined second distance.