A method for determining optical properties of human tissues by measuring diffuse reflectance with CCD

摘要

It is important to measure optical properties noninvasively, quickly and accurately in vivo for disease diagnostics and medical therapeutics. In this study, we measured the absorption coefficient and the reduced scattering coefficient of human tissues by measuring diffuse reflectance with CCD, examined the techniques involved, such as quantization of diffusion approximation theory, effective reverse fitting algorithm, and the data selection and processing method, and finally concluded about the accuracy of this method. The experimental results indicate that the error is less than or equal to 8% using the diffusion theory, under the condition that the reduced scattering coefficient is one order of magnitude greater than the absorption coefficient. The stability and precision of optical property measurements are significantly improved by using the multi-step iterative fitting method and using the ring areas to determine the diffuse reflectance center. The efficiency of reverse algorithm is greatly enhanced by selecting a one-dimensional array on the straight line crossing both the entry point and the diffusion center for fitting. The error of measured absorption coefficient and scattering coefficient of the Intralipid solution and human forearm tissues are less than 5% with our method. These results can provide important technical information for application of the diffusion theory.