Showing papers on "Thermography published in 1969"

Wavelength dependence of skin emissivity

Abstract: Determination of skin emissivity, particularly in the wavelength range 2 to 20 ?, is important for the interpretation of the scans obtained in clinical infra-red thermography. This emissivity can be inferred from the difference in apparent temperature for an area of skin and a black-body set to have the same true surface temperature. The approximations inherent in the previous use of the Dreyfus rule in this connection for calculation of emissivity over a range of wavelengths are discussed in detail.

The emission of infrared radiation from human skin—implications for clinical thermography

Abstract: Some of the infrared radiation emitted from the skin will have been transmitted from the deeper tissues which are at a higher (blood) temperature than the outer surface. Thus the apparent temperature of the skin in an infrared thermograph will be raised by 1–2°C immediately over a superficial blood vessel. This can be demonstrated in practice, particularly if the skin surface is cooled. The importance of these effects are considered in detail both theoretically and in clinical thermography.

Thermography of extremities after smoking

Abstract: The primary object of this report is to demonstrate the value of thermography as a skin-temperature measuring device. Thermography adds a new dimension to skin-temperature recording. Instead of getting inaccurate readings with contact devices such as thermocouples, subjects can be scanned without disturbance at a distance. The resulting thermal maps, or thermograms, may be analysed by several means with remarkable accuracy. The skin temperature changes of the extremities that occur after smoking can be graphically analysed in this manner. Thirty-five male and female volunteers were thermographed after smoking one cigarette. Decreases in skin temperature ranging from 0·5°C to 3°C were noted in the extremities of all participants, smokers and non-smokers alike. Individual responses were widely variable. No attempt was made to determine the possible causes for the decreases in dermal temperature.

New developments in breast thermography. High spatial resolution.

Abstract: Two design trends have become evident in the development of clinical thermo‐graphic equipment—higher frame rates which meet the requirements for real‐time presentation and novel color and isotherm techniques designed to increase the differential temperature capabilities of display systems. These developments, for the most part, have been accomplished at the expense of spatial resolution. Little has been reported on the characteristics of high spatial resolution thermography. With the rapid developments in detector technology, it has now become possible to retain the desired degree of temperature resolution at clinically acceptable frame rates while increasing spatial resolution. Such a system is presently being tested at the University of Texas M. D. Anderson Hospital and Tumor Institute and its performance compared with commercially developed thermographic units. The criteria for comparison are the diagnostic value of the thermograms and image quality as determined by the modulation transfer function. At the present time, the experimental thermograms indicate that high spatial resolution simplifies the recognition and classification of thermal patterns while decreasing the number of false‐positive examinations. Information may also be derived concerning the heat transfer processes involved. The experimental scanner is not suited for routine clinical use and theoretical calculations concerning the development of an optimal clinical scanning device are presented.

Variation of Effective Surface Emissivity with Angle and Implications for Clinical Thermography

Abstract: INFRARED scanners1 now find considerable application in clinical thermography. The image is interpreted in terms of differences in surface temperature, and local variations in apparent temperature of 2° C have been regarded as possibly indicative of pathology in, for example, attempts at early detection of breast cancer2. The energy received by the detector from any point in the field of view, however, depends on both the temperature and the emissivity of the skin surface.