2022 Volume 61 Issue 6 Pages 600-607
Terahertz (THz) imaging is a proposed non-invasive/non-staining visualization tool for cancer. However, THz investigation of early-stage cancer has hardly been conducted because of the spatial resolution of the THz measurement system, typically limited to several millimeters. Therefore, the use of point THz sources created by optical rectification in a nonlinear optical crystal excited by femtosecond pulse lasers has been proposed to overcome this problem. Our investigations revealed that the resolution was not limited by the wavelength of the THz waves but that of the laser source. Based on this finding, we have also developed a unique THz near-field microscope, named the SPoTS (scanning point THz source) microscope, with which early-stage breast cancer of less than 500μm can be visualized without staining but with a spatial resolution of ∼9μm. This review presented an overview of the SPoTS microscope and its application to cancer diagnosis, showing recent research findings in breast cancer evaluation.
