The future of terahertz imaging in medical applications looks promising
Tuesday, May 22, 2018
Terahertz (THz) imaging, which has been around for decades in the fields of submillimeter and far-infrared astronomy, is helping us probe beyond the skies above. In more recent times, say the last decade, THz imaging has moved into other fields like non-destructive testing for industrial applications, and airport security in the form of body scanners. The military sector also has interest for this technology.
And now there’s a great deal of interest and research about where terahertz imaging is being applied in the medical diagnostics field. Let’s take a closer look at this.
What is terahertz radiation anyway? It is a part of the broad electromagnetic spectrum that spans the region between far IR and millimeter wavelengths. It is often referred to as the terahertz gap and is formally defined as the spectrum from 30 µm (10 THz) to 3000 µm (0.1 THz).
And what is unique about it? First and foremost, terahertz radiation is non-ionizing, unlike X-rays and UV light: it is therefore safe for human tissue. In addition, it is heavily absorbed by moisture which in the medical imaging field can be a strong positive.
For instance, the presence of cancerous tissue generally leads to increased blood supply and water content. THz imaging, in this case, can provide an endogenous contrast between normal and cancerous tissue. Therefore, terahertz is eligible for use in many medical imaging applications including skin, oral, breast, gastric and colorectal cancers.
Many recent achievements in the application of terahertz imaging have dramatically enhanced early detection and treatment of skin, breast and colon cancer.
It turns out that the refractive index and absorption coefficient of the tumor tissue is high, compared to normal healthy tissue. Such distinction is possible due to the higher water content and structural change of the carcinoma.
Terahertz imaging provides a higher contrast image for the diseased tissue versus the healthy tissue, the former having a higher content in water. This can provide a way to more accurately define the exact margin (boundary) of the early-stage tumors.
In a real-time setting, terahertz imaging can, during a breast cancer surgery for instance, allow a doctor avoid removing healthy tissue around a tumor as a safety margin. They can actually make sure they are removing all of the diseased tissue, eliminating the need for multiple operations and minimizing the risk for the patient.
Clinical trials are under way in several hospitals around the world and the expectation is that terahertz imaging in the medical field will be a tremendous tool in the years to come.
We at Gentec-EO have supported terahertz research since 2007 with the introduction of our THz pyroelectric detectors and in 2008 our T-RAD broadband terahertz radiometer for the measurement of radiant flux (watts) and irradiance (watts/cm2). This video introduces our THz product family:
We’ve worked closely with researchers throughout the world who are developing terahertz sources, sensors, and systems to help them characterize the devices. We currently provide a diverse set of sensors and instruments that can be used to measure from nanowatts to watts and nanojoules to joules in the terahertz gap.
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