PROCEEDINGS ARTICLE | April 24, 2013
Proc. SPIE. 8585, Terahertz and Ultrashort Electromagnetic Pulses for Biomedical Applications
KEYWORDS: Tissues, Imaging systems, Calibration, Quartz, Water, Skin, Reflectivity, Terahertz radiation, Aluminum, In vivo imaging
Terahertz (THz) hydration sensing continues to gain traction in the medical imaging community due to its unparalleled
sensitivity to tissue water content. Rapid and accurate detection of fluid shifts following induction of thermal skin burns
as well as remote corneal hydration sensing have been previously demonstrated in vivo using reflective, pulsed THz
imaging. The hydration contrast sensing capabilities of this technology were recently confirmed in a parallel 7 Tesla
Magnetic Resonance (MR) imaging study, in which burn areas are associated with increases in local mobile water
content. Successful clinical translation of THz sensing, however, still requires quantitative assessments of system
performance measurements, specifically hydration concentration sensitivity, with tissue substitutes. This research aims
to calibrate the sensitivity of a novel, reflective THz system to tissue water content through the use of hydration
phantoms for quantitative comparisons of THz hydration imagery.Gelatin phantoms were identified as an appropriate
tissue-mimicking model for reflective THz applications, and gel composition, comprising mixtures of water and protein,
was varied between 83% to 95% hydration, a physiologically relevant range. A comparison of four series of gelatin
phantom studies demonstrated a positive linear relationship between THz reflectivity and water concentration, with
statistically significant hydration sensitivities (p < .01) ranging between 0.0209 - 0.038% (reflectivity: %hydration). The
THz-phantom interaction is simulated with a three-layer model using the Transfer Matrix Method with agreement in
hydration trends. Having demonstrated the ability to accurately and noninvasively measure water content in tissue
equivalent targets with high sensitivity, reflective THz imaging is explored as a potential tool for early detection and
intervention of corneal pathologies.
