Perhaps the earliest nonmilitary application of thermal IR imaging was in the field of health care diagnostics. As early as the late 1950s, a slow-scan thermal imager (six minutes per scan) was applied to the early detection of breast cancer and incipient stroke. This approach was based on the reasoning that in any warm-blooded creature, a disruption of normal function would produce a temperature change, most often resulting in a skin temperature deviation. It was further reasoned that since one side of the human body is for the most part a mirror image of the other, temperature variations between the left and right sides would very often indicate abnormalities. This reasoning proved correct, and although hampered by early opposition from many in the medical profession, IR thermal sensing and imaging (also known in the medical field as thermology) continues to be applied to human and veterinary medicine, biological studies, and other areas of life sciences diagnostics and research. This chapter illustrates some examples.
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