A Method for Medical Diagnosis Based on Optical Fluence Rate Distribution at Tissue Surface

Abstract

Optical differentiation is a promising tool in biomedical diagnosis mainly because of its safety. The optical parameters' values of biological tissues differ according to the histopathology of the tissue and hence could be used for differentiation. The optical fluence rate distribution on tissue boundaries depends on the optical parameters. So, providing image displays of such distributions can provide a visual means of biomedical diagnosis. In this work, an experimental setup was implemented to measure the spatially-resolved steady state diffuse reflectance and transmittance of native and coagulated chicken liver and native and boiled breast chicken skin at 635 and 808 nm wavelengths laser irradiation. With the measured values, the optical parameters of the samples were calculated in vitro using a combination of modified Kubelka-Munk model and Bouguer-Beer-Lambert law. The estimated optical parameters values were substituted in the diffusion equation to simulate the fluence rate at the tissue surface using the finite element method. Results were verified with Monte-Carlo simulation. The results obtained showed that the diffuse reflectance curves and fluence rate distribution images can provide discrimination tools between different tissue types and hence can be used for biomedical diagnosis.

Simulating Light Diffusion in Human Brain Tissues Using Monte-Carlo Simulation and Diffusion Equation

“…A model of 2 cm width and 2 cm height square was created. Then, a point representing the laser source was located at (0.2, 1) to simulate the distant-detector experimental conditions [8]. The geometry of the model, and the produced finite element mesh is presented in Figure 1.…”

“…Monte-Carlo simulation [5], diffusion equation [6] and adding doubling [3,7] method are examples of the forward models. While, Kubelka-Munk [8], inverse Monte-Carlo [9] and invers adding doubling [10] are inverse models.…”

Toward Better Medical Diagnosis: Tissue Optical Clearing

“…After applying optical clearing agents (OCAs), tissue optical scattering parameters "anisotropy and scattering coefficient" have to be calculated to ensure the reduction in the scattering properties of the treated tissue. Determination of tissue optical parameters can be achieved using either integrating sphere measurements [6] or distant detector based configuration [7].…”

Identifying different types of tumors in human brain, breast, and uterus according to their optical properties in the red to near-infrared region

“…The optical absorption and scattering properties of any biological tissue can be utilized as indictors for tissue health [9] as they are directly related to tissue chromophores concentrations including water contents, oxygenation of hemoglobin and melanin concentration [10,11]. Moreover, tissue diffuse reflectance is considered as a finger print for each tissue type and condition as it changes upon appearing any abnormality in the tissue [12]. Therefore, both tissue optical parameters and diffuse reflectance profile can powerfully assist in the process of medical diagnosis and therapy monitoring [6,13–15].…”