What is Computed Tomography (CT or CAT-scan)?
Computed Tomography (CT) was introduced in the early 1970’s and is one of the most common cross-sectional imaging modalities in use today. In CT, very fine x-ray beams are sent through the body to detectors that are located in a circular array around the patient. This data is sent to a computer which quickly processes the information and reconstructs an image. Essentially, CT images are reconstructed from hundreds of thousands of different radiographic projections. The tissue images that show up on the monitor consist of white, black, and shades of gray, called the gray scale. The amount of gray shown indicates the ability of the tissue to absorb or transmit (attenuate) the x-ray beam. Manipulation of the gray scale allows better differentiation of tissue type and increased ability to detect lesions over conventional radiography. Changes in the expected attenuation of the x-ray beam may indicate a disease process. Positive contrast media (dye) can also be injected into the patient’s bl
