Transmission of NIR Radiation Through Multi-layer Mouse Head at Scalp Skin Optical Clearing

Theoretical and experimental studies of infrared radiation transmission through the upper part of the mouse head-including the scalp, skull, gray matter, and white matter-with optical clearing of the skin are presented. Using known scattering and absorption coefficients, along with experimentally determined geometric parameters and their changes during the optical clearing process, Monte Carlo simulations were carried out for a four-layer mouse head model. Radiation transport within the tissue was described using the Bethe-Salpeter equation. Simulations were performed for two infrared wavelengths, with scattering anisotropy accounted for via the Henyey-Greenstein phase function. The spatial distribution of transmitted radiation intensity in the cross-section of the white matter was investigated as a function of both the wavelength and the size of the incident beam. The simulation results demonstrated good quantitative agreement with experimental data and can be extended to other tissues with controllable scattering properties, including those modified by ionizing radiation exposure.