Modern Thermologists use digital cameras that record infrared radiation emitted by the human body and convert them into temperature readings and plot them on a computer screen. Thermologist's are then able to identify areas of hot and cold in relation to the opposite side of the body. Areas with decreased blood flow will have colder temperature readings and areas of increased blood flow will have warmer temperature readings.
Breast tumors and some other tumors are able to found on thermal imaging through the process known as Angioneogenesis, the formation of new blood vessel that supply nutrients to a tumor. This asymmetric increase in blood flow creates an increase in
temperature that can be picked up by medical thermal cameras. Many times this blood supply increases over time as a tumor grows and is an important part of baseline studies and the ability for them to identify a tumor at the earliest possible moment.