Potential biomedical applications
Non-invasive technique for early detection of cancer
The latest research aimed at examining terahertz properties on skin cancer, breast and colon cancer tissues discovered that refractive index and absorption coefficient of the tumor tissue are higher in comparison to the normal tissue. Such distinction is possible due to higher water content and structural changes that occur in carcinoma (e.g. increased cell and protein density observed in cells affected by disease). Terahertz pulse imaging technique is highly sensitive to water concentration (because of the latter attenuation) and therefore water absorption is evident in the terahertz properties measured for soft tissues, which explains the contrast seen between muscle and adipose tissue, for instance.
Consequently, T-ray images can distinguish between healthy tissue and basal cell carcinoma and therefore help in mapping the exact margins of tumors in earlier stages. (The most promising are such non-invasive terahertz imaging techniques as THz pulse imaging, THz time domain spectroscopy (TDS-THz), continuous wave terahertz (CW-THz), and other THz generation/detection methods).
RTHz Imaging: Biomedical Applications
Mark Stringer, Institute of Microwaves and Photonics, School of Electronic and Electrical Engineering, University of Leeds
Ex-vivo spectroscopy / imaging of tissues (biopsy)
Terahertz time-domain spectroscopy (TDS-THz) can breach the shortcomings of other medical diagnostics in rendering adequate images of the affected tissues or suspected areas. Many researchers confirm that at certain frequency range most tumors have lower absorption than normal tissues. The obvious conclusion here is that THz imaging can ‘distinguish’ the tumors (inflamed areas) from normal tissues. In addition to helping save human lives, such biopsies enhanced by T-ray spectroscopy saves a lot of time and efforts by reducing the number of second surgical procedures in breast and skin cancer treatment cases.
One of the greatest biomedical potential of T-ray imaging is associated with Molecular spectroscopy for diagnostics, which is exponentially advanced and moved closer by the progress.
In-vivo examination of tissue via spectroscopy / imaging
Imaging in THz frequency range can be used to render a real-time imaging during surgical operations to avoid cutting off a lot of healthy tissue, and exclude leaving any part of carcinoma in a patient’s body. This in its turns considerably reduces the likelihood of the need for a repeated invasive operative intervention (s) in the future.
Terahertz imaging (especially THz Pulse Imaging (TPI) can show good contrast between different animal tissue types and, accordingly, can enhance the effectiveness of medical diagnostics and tangibly complement histological analysis. Such diagnostic is believed to allow obtaining the spectrum of each pixel in the image individually.
Please click to see picture «Contribution of THz technology in the future (10 years)» by National Institute of Information and Communication Technology, Japan
Those spectra that represent different tissue types happen to be markedly different. This suggests that the spectral data inherent in T-ray image might be used to distinguishing between soft and hard tissue at each pixel in an image and provide other diagnostic information not afforded by currently available conventional imagine techniques.
In vivo molecular imaging is considered as the next frontier in medical diagnostics, which in the ideal situation, would be performed non-invasively.
A real-time terahertz imaging system consisting of terahertz quantum cascade laser and uncooled microbolometer array detector
Hosako, N. Sekine, N. Oda, M. Sano, S. Kurashina, M. Miyoshi et al., SPIE Vol. 8023, 80230A, doi: 10.1117/12.887 947/
Preventive healthcare and blood testing
Additionally, very recent research project in THz emission at the level of a few tens of GHz and at 300 GHz showed sensitivity to the blood glucose level. This invention opened immense opportunities for preventive healthcare (blood analysis) for non-invasive measurement of glucose and other biomedical relevant molecules involving sub-THz and Terahertz ranges, up from aprx. 20GHz on.
It is now evident that different types of biomolecules leave distinctive spectral fingerprints in the THz region, which considerably widens the coverage of THz technologies application to include in-vitro and in-vivo measurements of small molecules (such as glucose, lactate, urea) of clinical importance in PoC and diagnostic systems.
Diagnostics of osteoarthritis, arthritis etc
All in all there are several Terahertz imaging modalities that represent high interest for medicine, in particular, Terahertz pulsed imaging (TPI), THz time domain spectroscopy (TDS-THz), continuous wave terahertz (CW-THz), and a few other THz generation/detection methods.
As it is safe for humans, these Terahertz technologies can open up infinite opportunities for medicine, that like other applications can surely benefit from harmless penetrating capability of Terahertz waves to make the invisible visible and visualize internal information about physical objects.