thermography

thermography , contact photocopying process that produces a direct positive image and in which infrared rays are used to expose the copy paper. In a specially designed machine the original is placed in contact with a copy paper containing a heat-sensitive substance. As the infrared rays produced in the machine impinge on the dark or printed regions of the original, the heat generated is transferred to the adjoining areas of the sensitive paper. These areas become dark as well, creating an image of the original. As infrared rays are difficult to focus, the image formed is lacking in sharpness, resolution, and detail. The copies remain sensitive to heat, so that they may darken further with age. The advantages of this process are that it is low in cost and fast and can be performed with simple equipment.

thermography A medical technique that makes use of the infrared radiation from the human skin to detect an area of elevated skin temperature that could be associated with an underlying cancer. The heat radiated from the body varies according to the local blood flow, thus an area of poor circulation produces less radiation. A tumour, on the other hand, has an abnormally increased blood supply and is revealed on the thermogram (or thermograph) as a ‘hot spot’.

thermography (ther-mog-răfi) n. a technique for measuring and recording the heat produced by different parts of the body by using photographic film sensitive to infrared radiation. The picture produced is called a thermogram. A tumour with an abnormally increased blood supply may be revealed on the thermogram as a ‘hot spot’.