<i>In vivo</i>study of human skin using pulsed terahertz radiation

TLDR

Terahertz imaging distinguishes skin cancer from healthy tissue largely because tumors have different water content, which produces a strong contrast at THz frequencies. This study investigates the interaction of terahertz radiation with normal human skin in vivo, aiming to inform the development of improved diagnostic imaging algorithms for skin cancer and other disorders. Reflection measurements were taken from the forearm and palm of 20 volunteers, and individual responses were compared to the mean response for each skin area. The finite‑difference time‑domain model accurately simulates terahertz interaction with normal skin, as confirmed by the in‑vivo data, particularly for the volar forearm.

Abstract

Studies in terahertz (THz) imaging have revealed a significant difference between skin cancer (basal cell carcinoma) and healthy tissue. Since water has strong absorptions at THz frequencies and tumours tend to have different water content from normal tissue, a likely contrast mechanism is variation in water content. Thus, we have previously devised a finite difference time-domain (FDTD) model which is able to closely simulate the interaction of THz radiation with water. In this work we investigate the interaction of THz radiation with normal human skin on the forearm and palm of the hand in vivo. We conduct the first ever systematic in vivo study of the response of THz radiation to normal skin. We take in vivo reflection measurements of normal skin on the forearm and palm of the hand of 20 volunteers. We compare individual examples of THz responses with the mean response for the areas of skin under investigation. Using the in vivo data, we demonstrate that the FDTD model can be applied to biological tissue. In particular, we successfully simulate the interaction of THz radiation with the volar forearm. Understanding the interaction of THz radiation with normal skin will form a step towards developing improved imaging algorithms for diagnostic detection of skin cancer and other tissue disorders using THz radiation.