Preliminary Studies on the Photon Path in Breast Tissue Model by NIR-TRS

Abstract

A typical tumor releases angiogenesis factor that induces the capillary growth around the tumor and, therefore, a greater amount of blood is present around the tumor. A tumor usually, therefore, becomes a local absorber due to its higher hemoglobin concentration. The ultimate goal of this project is to localize the position of a tumor in a breast tissue at an early stage using near infrared spectroscopy.

Computer simulations were performed to obtain TRS spectra at various locations in a system with optical properties of human breast. The time domain output pulses, then, were transferred to the frequency domain and the data were analyzed at various modulated frequencies. The changes in the photon path with respect to the frequency were systematically studied for absorber localization in three-dimensions.

Two different source-detector configurations, transmittance and reflectance were studied to explore the best TRS spectra acquisition procedure for tumor localization. Our previous study results have shown that in reflectance measurements the photon penetration depth is dependent on both the source-detector (S-D) separation distance and the modulation frequency. More specifically, the photon penetration depth decreases at smaller source and detector separations and higher frequencies. In this study, the effects of these two parameters on the photon path were studied in both transmittance and reflectance. This study results may be used effectively in determining the position.