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Proceedings Paper

An analytical model of skin: comparison with experimental results in vivo
Author(s): Ruth M. Woodward
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Paper Abstract

Terahertz pulsed imaging is a non-invasive, non-ionizing imaging technique, using electromagnetic radiation defined in the frequency range 0.1 THz to 10 THz. Using reflection imaging systems with a frequency range 0.1 THz to 4 THz a far field diffraction limited lateral resolution of 3 mm to 110 microns is attainable. A three layer analytical model has been developed to simulate the hydration properties of skin in reflection. Earlier in vivo hydration measurements of the volar forearm and palm of the hand (thenar) are compared to this model. The time-domain analysis technique “time post pulse” (TPP) used to differentiate between diseased and normal tissue in a study of basal cell carcinoma was applied to the data. An increase in the value of TPP is observed with occlusion in the viable epidermis. This is attributed to an increase in the flux of water across the epidermis or dermis with increased stratum corneum hydration. This is verified by the literature. The change is observed in less than six minutes occlusion, making terahertz technology one of the most sensitive techniques for monitoring skin hydration levels. The contrast observed at the stratum corneum-viable epidermis interface is similar to that seen between diseased and normal tissue. Although water provides a good marker for studying diseased tissue, comparing results from DNA and protein analysis, it is not yet possible to conclude whether the contrast observed in basal cell carcinoma is due to increased water within the diseased tissue, a change in the vibrational modes of water with other functional groups, or a change in the vibrational modes of the functional groups alone. Further studies are required to determine whether terahertz technology is capable of differentiating between different histological subtypes in a collective system such as skin at a macroscopic level. The three layer analytical model provides a useful adjunct for identifying the source of contrast observed in the top surface of skin.

Paper Details

Date Published: 1 April 2005
PDF: 14 pages
Proc. SPIE 5692, Advanced Biomedical and Clinical Diagnostic Systems III, (1 April 2005); doi: 10.1117/12.597340
Show Author Affiliations
Ruth M. Woodward, HT Consultants Ltd (United Kingdom)
Cavendish Lab., Univ. of Cambridge (United Kingdom)

Published in SPIE Proceedings Vol. 5692:
Advanced Biomedical and Clinical Diagnostic Systems III
Tuan Vo-Dinh; Warren S. Grundfest M.D.; David A. Benaron M.D.; Gerald E. Cohn, Editor(s)

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