Measurement of Optical Parameters in Vertebra Bones by Spatial Resolved, Steady-State Diffuse Reflectance

A new method to get the optical parameters of vertebra bones during pedicle screw insertion surgery was proposed. The method was based on the equation of spatially resolved, steady-state diffuse reflection. The diffuse reflectance was got at the positions of 0.2 cm distance from light source. The measurement system based on light intensity was designed. The light source was 760 nm light emitting diode (LED) and was modulated by square wave at 20 Hz. The lock-in amplifier circuit was used to detect the light intensity. The computer simulation and pig vertebra experiments have been used to validate the method and system. In the theory, the absorption coefficient (u_a) and reduced scattering coefficient (u_s´) were able to get by the diffuse reflectance. The measurement results of the system show that the light intensity values scattered from the cortical bones and cancellous bones in vertebra were distinguished. The paper shows the optical parameters of different bones in vertebra are different and provides an efficient method to identify the bone tissues for the future research.