Open Research Challenges and Opportunities in Terahertz Imaging and Sensing for Cancer Detection

Terahertz (THz) technology has come a long way since the inception of efforts to bridge the 'THz gap' which has seen the development of THz sources and detectors as well as various THz imaging and sensing systems. One of the application domains that will greatly benefit the salient characteristics of THz wave-based technology is the biomedical fraternity. THz technology is characterized by the promising capability to offer early, label free, non-invasive and non-ionizing cancer detection. Some progressive milestones have been achieved in the development of THz technology which is evident in the diversity of its applications spanning from Astronomy, nondestructive testing, material characterization and security inspection to biomedical more recently. However, some challenges still exist which call for research opportunities. In this paper, we provide perspective and recent trends in THz imaging and sensing through identification of existing challenges and research opportunities to facilitate the development of reliable and sensitive THz systems that can evolve into actual medical imaging modality. We highlight the THz imaging application for detection of various cancers. The merits of THz based imaging and sensing are presented and existing challenges identified with prospective opinions given to pave way for future research. Further, we discuss the recent advances in the development of THz technology and mention the contribution of near field techniques in breaking the diffraction limit through resonance and plasmonic metasurfaces, waveguides etc. We highlight the progress of machine learning based analytic algorithms, particularly deep learning in THz imaging.