Biomedical Terahertz Systems

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One quarter of Canadians die from cancer, being 80,000 Canadian deaths in 2015, and skin cancer is especially prevalent. In fact, skin cancer has a rate of occurrence equal to that of all other cancers combined. As early detection dramatically increases survival, there exists a longstanding need for quick, reliable, and widespread skin cancer detection.Recent advances in skin cancer detection have appeared through spectroscopy with near-infrared wavelengths. Unfortunately, these wavelengths struggle to probe subdermally and to distinguish benign and malignant lesions. However, terahertz (THz) spectroscopy is ideally suited to skin cancer detection. It can probe subdermally, from its deep THz penetration, and identify malignant lesions, from its high THz sensitivity to moisture. However, there are many challenges with oncological THz systems under development. These systems are prohibitively expensive, are much too large for widespread clinical use, and have long data acquisition times which are ineffective for in-vivo scanning of skin. These systems use conventional THz emitters, which require expensive and bulky titanium-sapphire lasers, and use conventional THz detectors, which operate through slow measurement techniques.The proposed work will develop oncological THz systems possessing the required functionality for skin cancer detection and diagnostics. This functionality will be achieved by addressing key issues related to THz emission and detection. Terahertz emitters will be developed that are compatible with inexpensive and compact erbium-doped fibre lasers (for inexpensive and compact oncological THz systems). Terahertz detectors will be developed that utilize a novel technique for short data acquisition times.The proposed work will use results from several pilot studies previously completed by the applicant. These pilot studies developed a photonic nanojet lensing technique which will enable the required compatibility between photoconductive THz emitters and erbium-doped fibre lasers. These pilot studies also developed a phase mask technique which will enable the creation of THz detectors with the short data acquisition times required for skin cancer diagnostics. Prototypes of the oncological THz systems will be developed as this technology is moved towards commercialization and widespread availability/impact. The developing oncological THz systems have great medical and commercial potential.