Search

Now, terahertz (THz) technologies have been actively studied and applied in various biomedical applications including cancer diagnosis. It is related with unique features of THz spectroscopy, such as high sensitivity to water and other polar molecules, the presence of resonant peaks of various biomolecules in the THz frequency range, harmless of THz radiation to biological tissues. In this work, we have investigated different types of gastric tissues using THz spectroscopy and obtain refractive indices in the frequency range from 0.2 to 1 THz. Fourier transform infrared spectroscopy (FT-IR) was also applied in order to see what’s components of tissues make the most significant contribution in optical response and, therefore, allow to discriminate cancer.

Terahertz time-domain spectroscopy is a unique spectroscopic technique that determines amplitude and phase change resulting from terahertz wave interaction with material. The method terahertz time-domain polarimetry may be an alternative method. It is a characterization technique in which the change of polarization state of the wave transmission through the sample is measured. We propose analytical description of extraction the diagonal and off-diagonal components of permittivity tensor of materials in the terahertz frequency range using terahertz time-domain polarimetry. Using the diagonal and off-diagonal components of the permittivity tensor of materials, the effective mass, Hall mobility, and scattering time can be calculated.

At present, due to the rapid development of THz technology in medical applications, it becomes urgent to develop stable test objects (phantoms) for calibration, optimization of the operation of devices, and verification of the research methods used. In this work, a five-component phantom has been developed based on water, glycerin, starch, bentonite, and gelatin, and it was shown that these phantoms can be used as indicators of the level of dehydration of the renal tumor tissue. The mechanical properties of the phantom were investigated, the dispersions of the refractive index and absorption coefficient of the biocomposite were determined in the range from 0.2 to 1 THz. To simulate the optical parameters of a phantom depending on the concentration of inclusions, an iterative method was developed and it was found that this method makes it possible to simulate the optical parameters of a phantom at low concentrations of bentonite. It is shown that in the structure of a five-component phantom, during fabrication, clusters of starch particles are formed, and the resonant interaction of the incident THz radiation with cluster particles leads to the excitation of whispering gallery modes.

Significance: A new concept of a biotissue phantom for terahertz (THz) biomedical applications is needed for reliable and long-term usage. Aim: We aimed to develop a new type of biotissue phantom without water content and with controllable THz optical properties by applying graphite powders into a polyvinyl chloride plastisol (PVCP) matrix and to give a numerical description to the THz optical properties of the phantoms using the Bruggeman model (BM) of the effective medium theory (EMT). Approach: The THz optical properties of graphite and the PVCP matrix were measured using THz time-domain spectroscopy, which works in the frequency range from 0.1 to 1 THz. Two phantoms with 10% and 12.5% graphite were fabricated to evaluate the feasibility of describing phantoms using the EMT. The EMT then was used to determine the concentration of graphite required to mimic the THz optical properties of human cancerous and healthy oral tissue. Results: The phantom with 16.7% of graphite has the similar THz optical properties as human cancerous oral tissue in the frequency range of 0.2 to 0.7 THz. The THz optical properties of the phantom with 21.9% of graphite are close to those of human healthy oral tissue in the bandwidth from 0.6 to 0.8 THz. Both the refractive index and absorption coefficient of the samples increase with an increase of graphite concentration. The BM of the EMT was used as the numerical model to describe the THz optical properties of the phantoms. The relative error of the BM for the refractive index estimation and the absorption coefficient is up to 4% and 8%, respectively. Conclusions: A water-free biotissue phantom that mimics the THz optical properties of human cancerous oral tissue was developed. With 21.9% of graphite, the phantom also mimics human healthy oral tissue in a narrow frequency range. The BM proved to be a suitable numerical model of the phantom.

Recent years, polarimetry in the terahertz frequency range has gained popularity. Polarimetry is a technique used to measure the polarization state of electromagnetic waves transmitted through samples. The ellipticity angle, the azimuth rotation angle, complex optical properties of materials can be obtained by terahertz timedomain polarimetry. This allows for obtaining more comprehensive information about the object. In this paper, we study diagonal and off-diagonal components of the permittivity tensor of thin bismuth-based films using terahertz time-domain polarimetry

With the fast development of terahertz technology in medical diagnosis and monitoring, it has become important to investigate the application of THz radiation in the cancer treatment assessment during the therapy. In this paper, a buccal drug delivery system is studied as the first step towards this application. The drug delivery system is based on a gelatin-starch biopolymer matrix filled with plasticizing glycerol and various contents of reinforcing particles of bentonite clay. The biopolymers were subjected to morphology analysis using optical microscopy, analysis of mechanical tensile properties, and analysis of terahertz optical properties, followed by a theoretical approach of the experiment. The results show a visible effect of the bentonite content on both of the mechanical and terahertz optical properties of the biopolymer. These findings allow us to confirm the feasibility of using THz radiation for cancer assessment during therapies. The proposed biopolymer also has the potential to be applied as a substrate when carrying out in-vivo optical property measurement of biotissue in terahertz frequency range.

We propose a modified approach to more detailed study of gyrotropic materials using terahertz (THz) ellipsometry method based on the magneto-optical Kerr effect (MOKE). This approach allows to obtain polarization properties and to calculate the permittivity tensor of materials which are reflective or opaque in THz frequency range. The method allows to measure any values of the diagonal and off-diagonal components of the permittivity tensor and can be used for materials with a strong magneto-optical response.

In recent times, terahertz (THz) technologies have been actively applied in many biomedical research work, including gastric cancer diagnosis. In order to provide an effective removal of tumor during surgery, it is necessary to clearly distinguish it from different membranes of the stomach. In this work, we reported an investigation of various normal and cancer fresh gastric tissues using terahertz time-domain spectroscopy in the reflection mode. Refractive index and absorption coefficient of moderately differentiated and poorly differentiated gastric adenocarcinomas, as well as both serosa and mucosa were obtained in the frequency range from 0.2 to 1 THz. All cancer tissues were distinguishable from normal ones. The influence of the morphology of the investigated tissues on the obtained optical properties is discussed. The obtained results demonstrated a potential of THz time-domain spectroscopy to discriminate a tumor from normal serous and mucous gastric membranes. Thus, this method might be applied to gastric cancer diagnosis.

In this study we have obtained refractive indices, absorption coefficients and complex permittivities of mucous and serous fresh somach tissues using terahertz (THz) reflection time-domain spectroscopy. These optical properties were different for each type of the tissue, that can be explained by different morphology of the mucous and serous stomach membranes. The results of the study can be useful for intraoperative diagnostics of gastric cancer localized in different sides of the stomach.

Non-invasive diagnostics methods are very helpful for cancer diagnosis and they are a research hotspot in the field of biomedicine. Terahertz (THz) photonics is an emerging technology that can be applied in the field of medical diagnostics. This is due to unique features of THz radiation such as harmlessness to biological tissues, strong absorption by water, ability to identify various biomolecules, etc. In this work we have investigated different types of normal and cancer fresh tissues of the stomach using terahertz time domain spectroscopy in reflection mode. Refractive indices of mucous, serous and tumor stomach tissues were obtained in the frequency range of 0,2 - 1 THz. These optical properties are higher for cancer tissue than for mucosa and lower than for serosa. Thus possibility of discrimination of tumor from normal stomach tissue was demonstrated. This study has practical significance for the field of clinical cancer diagnosis and will help to better understand the specifics of the method of pulsed THz spectroscopy applicable to this field.