PROPERTY RELEASED. MODEL RELEASED. A patient in a CT scanner. A drip provides intravenous contrast fluid via a line into the patient's arm. Also known as CAT (computed axial tomography) scanning, CT (computed tomography) scanning is a diagnostic technique in which X-rays are passed through the body at different angles to produce cross sectional images. Sometimes a contrast fluid is administered intravenously via a drip during CT scanning. Contrast media are opaque to X-rays and enhance the contrast of the images, improving the detail of the scans. A computer then produces cross-sectional images of the tissue being examined. This technique provides clearer and more detailed information about body tissues than X- rays used by themselves.