Infrared thermography is a new diagnostic tool' which can be employed in a useful manner in numerous fields of medicine. This holds especially for angiology. As our experience has demonstrated, this simple method can be advantageous for diagnosis, control, and supervision of therapeutic effects. 2, 3 A short explanation of the diagnostic principle and its applicability for control of thrombolytic therapy is the purpose of this communication.
PRINCIPLE AND METHODThe temperature of the body surface and superficial vessels (e,.g., arteria dorsahs pedis) is mainly determined by the amount of blood flow. The emission of heat, either increased or decreased, which is radiated by the infrared portion of the spectrum with a wavelength from 2 to 20 ~ is recorded by a detector, which consists of an indium-antimonide cell. An electronic system converts the single impulses into a television picture, thus permitting measurement and photographic documentation on a screen.* A survey of the equipment used is shown in figure 1.The measurement of object temperatures is performed by use of so-called isotherms. Areas of the same emission are projected into the infrared picture, where they appear in a different width corresponding to the intensity of emission and calibration of sensitivity of the device. In the screeningthermogram, colder areas of the body appear darker than warmer ones, thus producing a temperature map of the body. It must be emphasized that infrared thermography, in contrast to infrared photography, registers the natural emission and not the reflection of artificial infrared radiation.As soon as an isotherm is induced into the screen picture corresponding to a certain surface temperature, all areas displaying the same temperature can be demonstrated. In this case the area is appearing on the screen as a white tape, distinctly differentiating from its surrounding. A scale on the right side of the cathode ray tube (appearing on the right side of the figure) corresponds to the sensitivity of the temperature range, while another scale on the lower margin of the screen permits an exact reading of the isotherms within the sensitivity chosen. With a temperature range of 20 (right scale) the lower scale (0 to 1.0) covers a temperature range of 0 to 20° C. If, however, the sensitivity 10 is used, the temperature range is from 0 to 10° C. Thus the method permits demonstration of the maximum difference of temperature of different body regions or between two corresponding extremities. Therefore the isotherms easily and rapidly permit a cartographic reconstruction of the
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