Ex Vivo Breast Tumor Identification: Advances Toward a Silicon-Based Terahertz Near-Field Imaging Sensor
Pfeiffer, Ullrich R., Philipp Hillger, Ritesh Jain, Janusz Grzyb, Thomas Bucher, Quentin Cassar, Gaetan MacGrogan, Jean-Paul Guillet, Patrick Mounaix, and Thomas Zimmer. “Ex Vivo Breast Tumor Identification: Advances Toward a Silicon-Based Terahertz Near-Field Imaging Sensor.” IEEE Microwave Magazine 20, no. 9 (2019): 32-46.
Terahertz waves cover photon energies that are orders of magnitude smaller (0.4– 40 meV) than the visual spectrum. Therefore, they provide additional information on intrinsic condensed-matter properties, making them attractive for imaging applications in the life sciences , . Furthermore, they do not have an ionizing effect and are considered biologically innocuous. The ever-present water in organic matter strongly absorbs terahertz waves, and subtle changes in the water concentration can be indicative of disease . However, the waves’ long wavelength (3 mm- 30 microns) severely limits their lateral resolution and creates challenges for high-resolution imaging of biological tissue on the cellular level, e.g., for tumor margin identification during cancer surgery.
“A commercially available TeraPulse 4000, with a modified reflection geometry setup as shown in Figure 3(a), was used in this study. The emitted submillimeter pulses were focused on a biological sample sandwiched between two 2-mm-thick C-cut sapphire substrates mounted on a motor stage to perform reflection terahertz imaging. The step sizes in the x and y directions were between 100 micron and 500 micron while the far-field limited spatial resolution at the sample was approximately 1 mm at 300 GHz. Coherent photoconductive detection of the reflected pulses”