Hardware and software requirements of clinical DAT

Abstract

Dynamic area telethermometry (DAT) is aimed at extracting pertinent information on the mechanism underlying periodic changes in temperature of surfaces, manifested in modulation of their IR emission. Such changes occur on human skin as a result of modulation of perfusion due to cardiogenic hemodynamics or neuronal control of blood flow through the vasculature. Clinical applications of DAT involve identification of areas of skin that how abnormal dynamic behavior. Periodic physiological changes in skin temperature range between 10 and 50 mK. Pathological changes in skin temperature dynamics are of the same order. Consequently, clinical uses of DAT require not only high sensitivity and spatial thermal resolution but also a high degree of temporal stability of both the offset and NEDT values of each detector element of the FPA. DAT also requires high rates of data acquisition to allow sufficient resolution of the frequency spectrum of skin's temperature modulation. Adequate DAT studies involve accumulation of 2048 images at a rate of 100 Hz. We found that QWIP cameras meet DAT's requirements of sensitivity, stability and accumulation rate. A single DAT study using a 256 X 256 array yields 256 MB of IR flux or temperature data for subsequent analysis. Interpretation of such an enormous amount of digital information within a reasonable timeframe poses severe software requirements, which have been met.