l as reducing the cost of treatment. By using a THz tomography setup, THz imaging can also be used as a tool to inspect wounds and burns, and to help dentists to detect and diagnose tooth decay and enamel erosion. Currently, X-rays are used for dental imaging which does not help in detecting the early-stage tooth decay [Crawley 5G Wireless Communication System in Healthcare Informatics et al. (2003)]. For medical practitioners, a miniaturized optical fiber-coupled terahertz (THz) endoscope system has been designed to help in diagnosis of various kinds of cancers present in the body [Ji, Lee, Kim, Son, & Jeon (2009)]. 12.3 METHODS OF THZ GENERATION Terahertz science and technology are becoming a popular area in recent research because of the progress both in nanotechnology research and development of high-power lasers. THz waves can be radiated from sources based on either an electronic technique or on optical techniques. Electronic sources rely on RF/MW techniques and optical sources depend purely on optical technologies. Even though the sources in the microwave and infrared frequency bands radiate terahertz with high efficiencies, there are some drawbacks like feasibility, source size, and SO forth. Hence to overcome these weaknesses in the techniques, an advanced method of THz sourcing using nano technologies can be used, which is based on a combination of electronic and optical techniques. The sources to generate the terahertz has been discussed in further subsections. 12.3.1 THz SOURCES USING RF/MW RADIATION Vacuum and solid-state devices are some of the electronic sources that can generate and detect terahertz signals. These sources work based on the principle of elec- tron beam and EMF interactions. There are some other electronic sources such as gyrotron, backward wave-oscillators, and travelling wave tubes that can produce THz frequencies below 1 THz using high-power. Even though they radiate high-power terahertz waves, they are bulky in size and a high magnetic field is required with a high input power. 