Continuous-wave circular polarization terahertz imaging.

Area of Science:

• Biomedical Optics
• Medical Imaging Technology
• Terahertz Spectroscopy

Background:

• Terahertz (THz) radiation is nonionizing and can differentiate between cancerous and normal tissues.
• Linear polarization-sensitive THz detection has shown promise for tumor margin delineation.
• Circular polarization-sensitive THz detection remains largely unexplored for biomedical applications.

Purpose of the Study:

• To implement and evaluate a reflective, continuous-wave THz imaging system for both linear and circular polarization-sensitive detection.
• To investigate the utility of circular polarization-sensitive THz imaging for delineating tumor margins in ex vivo human skin cancer specimens.
• To compare the performance of circular versus linear polarization-sensitive THz detection techniques.

Main Methods:

• Development of a reflective, continuous-wave THz imaging system operating at 584 GHz.
• Capability to illuminate samples with linearly or circularly polarized THz radiation.
• Collection and analysis of both cross- and copolarized signals remitted from the target sample.
• Imaging of a fresh ex vivo human skin tissue specimen with nonmelanoma skin cancer.

Main Results:

• Both linear and circular polarization-sensitive THz imaging techniques demonstrated contrast between tumor and normal skin tissue.
• Differences in image characteristics were observed between the linear and circular polarization techniques.
• The study successfully imaged a human skin cancer specimen using the developed THz system.

Conclusions:

• Circular polarization-sensitive THz detection shows potential for tumor margin delineation.
• Further research is needed to elucidate the contrast mechanisms involved.
• Quantification of the specificity and sensitivity of circular polarization-sensitive THz detection is required for clinical translation.