Horizontal-scanning attenuated total reflection terahertz imaging for biological tissues

Abstract

Significance: Terahertz wave is a potential tool for biological tissues due to its noninvasiveness and high sensitivity to water. Attenuated total reflection (ATR) with the characteristics of high sensitivity and nondestruction has been applied for THz imaging. Aim: We aim to develop an imaging methodology to facilitate practical application of THz ATR imaging. Approach: We have demonstrated a horizontally scanning THz continuous wave ATR imaging system. The effective imaging area was as large as the prism imaging surface by optimizing the ATR prism, and the influence of secondary reflection can be well avoided. By taking the image resolution and stability of this system into consideration, the incident angle α to the prism bottom was chosen to be 30 deg. Results: The image resolution of this system can be up to 400 and 450 μm in horizontal and vertical directions, respectively. Furthermore, U87-glioma regions of mice brain tissues with different sizes and C6-glioma regions of rat brain tissues with relatively large size can be differentiated clearly from normal brain tissues by this imaging system. The volume and location of the tumor region shown in the THz images are similar to those visualized macroscopically in the corresponding visual and H&E-stained images. Conclusion: We indicate terahertz horizontal-scanning ATR imaging technique with large effective imaging area, and high resolution could be used as an alternative method for label-free and high-sensitivity imaging of biological tissues.

Terahertz technology in intraoperative neurodiagnostics: A review

“…Second, to enhance the accuracy of the tumor margins delineation, in ref. 87 , a region-of-interest (ROI) segmentation method was developed for work with the 2.52 THz CW imaging system. This method combines a variety of signal processing techniques, including the block matching 3D denoising, fuzzy c-means clustering, morphology operation, and canny edge detection.…”

In situ terahertz reflective spectral detection of biological tissues using a transceiver‐microprobe

“…There have also been some other techniques based on different approaches, for example, in 2015, Doradla et al 12 demonstrated the first flexible THz waveguide-enabled endoscopic system for colorectal cancer detection; In 2020, Wu et al employed a scanning THz continuous wave ATR system to image rat brain tissues. 13 However, these new approaches still cannot detect small areas of biological tissue due to the limitation of THz beam spot sizes.…”

“…And the sample is usually covered by a flat window to reduce the diffusive reflection caused by the uneven sample surface, 11 in which, the extrusion often changes the sample morphology, resulting in deviations of signal distribution from that of the actual surface. There have also been some other techniques based on different approaches, for example, in 2015, Doradla et al 12 demonstrated the first flexible THz waveguide‐enabled endoscopic system for colorectal cancer detection; In 2020, Wu et al employed a scanning THz continuous wave ATR system to image rat brain tissues 13 . However, these new approaches still cannot detect small areas of biological tissue due to the limitation of THz beam spot sizes.…”

Behavioral Effect of Terahertz Waves in C57BL/6 Mice

“…In recent years, with the continuous development of terahertz technology, it has been gradually studied and applied in various fields: remote sensing radar [ 3 ], material structure detection [ 4 ], data transmission [ 5 ], communication [ 6 ], security [ 7 ], and counter-terrorism [ 8 ]. In biomedicine, THz waves have the characteristics of low energy and non-ionizing radiation, and it will not cause harmful damage to biological tissues or organisms [ 9 , 10 ]; therefore, THz are used to identify and distinguish various biological small molecules [ 11 ], macromolecules [ 12 , 13 , 14 ], biological information extraction [ 15 ], and drug component detection [ 16 ].…”