Terahertz Dielectric Characterization of Three-Dimensional Organotypic Treated Basal Cell Carcinoma and Corresponding Double Debye Model

Abstract

The potential of terahertz (THz) spectroscopy and imaging in skin cancer detection and mainly basal cell carcinoma (BCC), the most common type of skin cancer, was previously studied. Thanks to the significant absorption of THz waves by hydrogen bonds of water and the higher hydration of tumors than normal skin, it is considered an ideal non-invasive tool for early cancer detection. Despite this potential, there is a lack of study on the THz characterization of treated tumors with anticancer drugs to constitute innovative approaches for chemotherapeutic research, and this is an inspiration for the current study. Previous THz spectroscopy measurements are based on freshly excised tissue and suffer from environmental impacts on tissue and also limit performing a thorough analysis of the effect of different biological parameters. Thus, we have cultured a three-dimensional (3D) organotypic model of BCC tumor to study the THz electromagnetic parameters of tumor in different stages along with the impact of AG1478 anticancer drug on its THz spectra. Measurements are performed in the frequency range of 0.4 to 1.6 THz, and the corresponding refractive index, absorption coefficient, and complex permittivity of normal skin, BCC, and treated BCC have been compared. Furthermore, an enhanced combinational optimization algorithm is developed to calculate the parameters of the double Debye (DD) dielectric model to explain better the discrimination of treated and untreated tumors with normal skin.