Thermography is a technique for sensing hot and cold areas of the body by means of an infrared camera taking thermal images. It does not involve radiation, or putting anything else in the body. Diseases that manifest increased or decreased blood flow present thermographic patterns that may possibly be distinguished from normal areas. Thermography for use in cancer screening is based on the concept that cancer gives off more heat than normal tissue. Thermography can detect subtle changes in breast physiology up to ten years before a cancerous tumor can be detected by other methods such as mammography.