CT machines produce a thin fan of radiation that is beamed through the body. This fan or radiation "slice" is received by detectors in the machine. The amount of radiation beamed through the body and picked up by the detectors on the other side will be affected by the density of the body parts in between. The CT scanner takes several views of each part and then reconstructs the "slices" into a 3D image for viewing.
Bone imaging and the elimination of overlap are the main advantages of CT. Some areas of the body are hard to see with traditional radiographs (X-rays) or ultrasound, such as when one organ is located on top of another or a body area of interest lies beneath bone, such as the brain. In these cases, tomographic, or slice, images can allow veterinarians to visualize what lies beneath. CT is extremely useful to diagnose particular forms of elbow dysplasia, as it eliminates the overlap of the affected structures, which can be confusing on radiographs (X-rays).
CT can be used to image the skull and spine, assessing these complex structures for fractures, tumors or infection. Because of the speed of modern scanners, there are also a number of specialized studies that can be done to help diagnose abnormalities of the blood vessels of the liver and lungs, and to help look at blood vessels associated with cancerous tumors. CT scans are preferred for the imaging of many types of cancer and are most commonly used to assess cancer of the nose. These scans are also useful when analyzing a complex skeletal structure, such as the skull or spine and in assessing the lungs and areas of the abdomen.