CAT scanner is the most modern instrument used as a medical diagnostic tool. It is in fact a modified technique of using X-rays for diagnostic purposes. It can detect the diseases of brain, kidney, liver, abdomen etc.
The word CAT is an abbreviation of Computerized Axial Tomography. CAT scanner was invented in 1972 by a British electronic engineer Godfrey Hounsfield and a U.S. physicist Allan Cormack. For this invention both these scientists were awarded jointly the Nobel Prize for medical science in 1979.
CAT scanners are of two types: head scanner and body scanner. Head scanner is used to diagnose brain diseases. With this, brain tumour, brain haemorrhage, clots in the brain etc. can be identified. Body scanner is used to diagnose different diseases of stomach, liver, chest etc.
A CAT scanner consists of an X-ray source from which the rays can be allowed to fall on any part of the body. Opposite to the X-ray source, there are many detectors which receive information from various body parts. In the middle, there is a stretcher for the patient. It is operated by a motor. Detectors are usually made of sodium iodide, calcium fluoride and bismuth germinate. Modern equipments consist of up to 300 detectors.
X-ray source produces pulses of X-rays in an interval of 2 to 3 seconds which fall on the different body tissues. On passing through the different tissues they carry the information to the different detectors. These detectors are connected to a computer. For example, a scanner with 300 detectors will send 300 x 300 = 90,000 signals to the computer after receiving 300 X-ray signals. These signals are analyzed by the computer and projected on the TV screen in the form of a picture. The computer is connected to a television screen. The signals coming from the computer are in accordance with the density variations of the body tissues. These signals are projected on the TV screen in the form of the body organ. This picture gives the clue to the disease. The picture from the TV screen is recorded permanently on a bromide paper. Doctor can know the disease from this photograph, and can give the proper treatment.
Another advantage of CAT scanner is that the doctor can check whether the treatment being given to the patient is effective or not. This information is obtained by scanning the body of the patient repeatedly.
Nowadays almost all hospitals, nursing homes have CAT scanners equipped with the latest technical knowhow for diagnosis of different diseases.