Correcting for Emissivity Automatically
Biological tissue has high emissivity, i.e. ~0.95. Accordingly,
the reflected compo-
nent will be about 5% of the energy mea- sured by the DermaTemp, which
translates to an abso- lute error of ~1°F
(0.5°C). In addition, skin emissivity varies due to color, texture, etc. over the approximate range of 0.92 to 0.98. An uncertainty of approxi- mately ±1°F (0.5°C) results from this emissivity variation, which can appreciably influence the assessment of a subtle perfusion issue.
A more significant er- ror is due to the re-
flected energy, which can vary considerably if the ambient radiation includes sunlight, radi- ant warmers, etc. To solve this problem the
DermaTemp is equipped with a unique patented feature called Automatic Emissivity Compensation System (AECS). The reflective
cup on the end of the probe automatically compensates for emissivity when it is touching, or brought to within approximately 1mm of the sur- face. By excluding ambient radiation, and replacing it with reflections of emitted radiation, the emissivity is corrected, and the accurate tem- perature indicated
Detection by Exception
The distribution of the temperature on the body surface varies appre- ciably. For example, on a normal individual, the highest average skin temperature is the forehead at 34.5°C (±0.73°C) and the lowest aver- age temperature is the toes at 27.1°C (±2.72°C).1 Considering the temperature of the skin is highly influenced by ambient temperature, one could wonder what diagnostic role, if any, temperature would play. The answer is that it plays a significant role, and the reason is the
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