Abstract
Liquid crystals, encapsulated in a plastic sheet, have a clear potential for use in the medical field. However, the development and use of the technique of thermography in the U.S.A. has not been accepted in Britain. This is a result of doubts concerning the technical details of the material and its use. This study was initiated to investigate thermography to detect injuries of the foot related to sportsmen and women. The experimental section was divided into 5 separate sections - the establishment of the photographic technique, the care of liquid crystals, the stabilization of patients' skin, the effect of pressure, spread and fade on the thermal image and the effect of skin condition on the thermogram. The photographic technique was established first as it was to be used throughout the study and discrepancies would have led to problems in interpretation because of colour and lighting differences. Comparison of used (and incorrectly stored) film and new film showed that correct storage preserved the characteristics and therefore accuracy of the film. Monitoring of patients' skin temperature during stabilization resulted in the establishment of a 10 minute stabilization time before thermographic screening. At this point starting temperature of the foot was not significant and a definition of stability (Time range = 0-3 minutes, temperature range = + or - 0.5 C) was reached for all subjects tested. Pres sure/weight was shown not to affect the thermal image. If the effect had been positive the reliability of the whole study would have been questioned. Spread of the image was shown not to occur except at the borders of old incorrectly stored film. Fade, and therefore degree of photographic delay after patient contact with the liquid crystals, was of a linear pattern but photographs were taken immediately to avoid potential problems of the disappearance of the image of cool areas and subsequent difficulties in interpretation. The skin condition of the subject (wet or dry) was found not to affect the thermal image and therefore made techniques to dry the skin unnecessary. These techniques of drying could seriously affect thermographic results and reliability. Pilot studies of subjects with various foot conditions were carried out and are illustrated in Appendix I. Thermal images of subjects were taken in conditions representing the average consulting room, after the established stabilisation time and after a period of 10 minutes jogging (depending on type of injury or condition). In some cases an abnormal thermogram was evident after only the stabilization period but some feet required the further stress of exercise before problem areas became apparent. Suggestions for further research and application are discussed.