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A CAT (computerised axial tomography) scanner uses a series of X-ray beams to build up images of the body in slices. Unlike an X-ray, which sends one beam of radiation through the body, a CT scanner emits a succession of narrow beams as it moves through an arc. This produces a very detailed image that is not possible from a normal X-ray.
The X-ray detector within a CT scanner can see hundreds of different levels of density, including tissues within solid organs such as the liver. This information is then sent to a computer, which builds up a cross-sectional image of the body and displays it on the screen.
CT scans are commonly performed on the head and abdomen. Head scans are an effective method of checking the brain for suspected tumours, bleeding, or swelling of the arteries. They are also useful for investigating the brain following a stroke.
Abdominal CT scans are used to detect tumours and to diagnose conditions in which internal organs, including the liver, kidneys, pancreas, intestines, lungs are enlarged or inflamed.Tears (lacerations) of the spleen, kidneys or liver (that might happen as a result of a serious road traffic accident), can be revealed by CT scan
.CT scanning can identify normal and abnormal tissue, making it a useful tool to plan areas for radiotherapy treatments and as a guide for taking tissue samples and needle biopsies.CT scans may also be used to assess vascular (blood flow) conditions to different parts of the body. Also to assess injury and disease to bones, particularly in the spine and to assess bone density when investigating osteoporosis
CT scans involve exposure to radiation in the form of X-rays. The level of radiation used is kept to a minimum to prevent damage to body cells (the dose is said to be about the same as the average person receives from background radiation in three years). Pregnant women should not have a CT scan, as there is a small risk that X-rays may cause an abnormality to the unborn child. Be sure to tell your doctor if you think there is a chance that you may be pregnant, before having a scan.
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