Terahertz Pulsed Imaging of Skin Cancer in the Time and Frequency Domain

University of Cambridge, Cambridge, England, United Kingdom
Journal of Biological Physics (Impact Factor: 1.29). 06/2003; 29(2-3):257-9. DOI: 10.1023/A:1024409329416
Source: PubMed


Terahertz Pulsed Imaging(TPI) is a new medical imaging modality forthe detection of epithelial cancers. Overthe last two years this technique has beenapplied to the study of in vitrobasal cell carcinoma (BCC). Usingtime-domain analysis the contrast betweendiseased and normal tissue has been shownto be statistically significant, andregions of increased terahertz (THz)absorption correlated well with thelocation of the tumour sites in histology.Understanding the source of this contrastthrough frequency-domain analysis mayfacilitate the diagnosis of skin cancer andrelated skin conditions using TPI. Wepresent the first frequency-domain analysisof basal cell carcinoma in vitro,with the raw power spectrum giving aninsight into the surface features of theskin. Further data manipulation is requiredto determine whether spectral informationcan be extrapolated at depth. These resultshighlight the complexity of working inreflection geometry.

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    • "The results of the present paper are of principal importance for further development of novel methods of skin diagnosis and therapy based on THz technology and, in particular, on TPS. All the methods to noninvasively diagnose skin cancers [37]–[40], [60], [61] and burns [56]–[59] based on THz absorption spectroscopy , as well as all the approaches for principal component analysis [40], [60], should be adjusted to account for the variations of the THz refractive index and absorption coefficient along the human body. V. CONCLUSION "
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    ABSTRACT: A method to reconstruct the terahertz (THz) refrac-tive index and absorption coefficient of in vivo tissue using THz pulsed spectroscopy (TPS) has been proposed. The method utilizes a reference THz window to fix the sample of interest during the TPS reflection mode measurements. Satellite pulses caused by multiple THz-wave reflections in the reference window are taken into account to accurately solve the inverse problem. The stability of the proposed method in the presence of various factors, including digital noise in the TPS waveforms and fluctuations of the reference THz window position, has been accurately analyzed. The method has been implemented to study in vivo the THz refractive index and absorption coefficient of the human skin. The skin from three persons has been measured, and the results agree with the well-known data on healthy skin spectroscopy in general, except for several regions of the skin. Thus, for the elbow, the hand, the knee, and the heel the THz refractive index and absorption coefficient considerably differ from the average values. The observed results are of principle importance for further development of novel approaches to skin diagnosis based on THz technologies. Index Terms—Absorption coefficient, inverse problem, material parameters, refractive index, spectroscopy of the skin, terahertz pulsed spectroscopy, THz technology.
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    • "A great deal of attention has been paid to THz imaging system with biomedical applications due to the moderate wavelength of THz signal that can leverage advantages of both millimeter-wave (mm-wave) and optics, such as high spatial resolution, good penetration depth to dielectric material or human tissue with no harmful ionization [1]–[3]. Recently, remarkable contrast in skin and breast cancer has been demonstrated in THz images [4], [5]. Compared to the prevailing diagnostic methods such as confocal microscopy and optical coherence tomography (OCT), THz radiation shows much higher penetration depth (1–3 mm) into human skin, which can be leveraged into the diagnosis of cancer-related diseases. "
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    ABSTRACT: A 239-281 GHz sub-THz imager with circular- polarize d substrate-integrated-waveguide (SIW) antenna is demonstrated in CMOS 65 nm process with high spectrum resolution and high sensitivity for sub-THz spectroscopy imaging system with consideration of depolarization effects. The sub-THz imager is a receiver that consists of a circular polarized substrate integrated waveguide (SIW) antenna, down-conversion mixer and power gain amplifier (PGA). The proposed receiver is measured with -2 dBi conversion gain over 42 GHz bandwidth, -54.4 dBm sensitivity at 100 MHz detection resolution bandwidth, 6.6 mW power consumption and 0.99 mm2 chip area. Moreover, frequency dependent sub-THz images are demonstrated by the proposed receiver.
    Full-text · Article · Nov 2014 · IEEE Transactions on Terahertz Science and Technology
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    • "Recently, the possibility of THz applications has spread to various research fields and industries, e.g. medical diagnosis234567, drug inspection8, security applications9, chemical analysis1011, etc. In particular, THz technology is extremely important for wireless telecommunications12. Higher speed is critical for wireless communications and the THz frequency region is promising for this purpose. "
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    ABSTRACT: We experimentally demonstrate control over the group delay of narrow-band (quasi continuous wave) terahertz (THz) pulses with constant amplitude based on optical switching of a metasurface characteristic. The near-field coupling between resonant modes of a complementary split ring resonator pair and a rectangular slit show an electromagnetically induced transparency-like (EIT-like) spectral shape in the reflection spectrum of a metasurface. This coupling induces group delay of a narrow-band THz pulse around the resonant frequency of the EIT-like spectrum. By irradiating the metasurface with an optical excitation pulse, the metasurface becomes mirror-like and thus the incident narrow-band THz pulse is reflected without a delay. Remarkably, if we select the appropriate excitation power, only the group delay of the narrow-band THz pulse can be switched while the amplitude is maintained before and after optical excitation.
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