An atom is the basic particle of matter, the smallest (~10^-8cm) particle of a chemical element. Atoms consist of a nucleus with neutrons, positive charged protons and orbiting negative charged electrons. The chemical properties of elements are defined largely by the number of protons in the nucleus. The number of electrons is similar to the number of protons. An atom is ionized when the number of electrons is not equal to the number of protons; the resulting electrical charge depends on the difference between the number of protons and the number of electrons.

See Rutherford-Bohr Atom Model, Ionization.

Baro-Cat® is a barium sulfate suspension for use as an aid for computed tomography of the gastrointestinal tract. The contrast medium contains additional pineapple-banana flavor suspending agents, simethicone, potassium sorbate, citric acid, sorbitol, artificial sweetener and water.
Individual technique will determine the suspension quantity and specific procedure used. For computed tomography of the upper gastrointestinal tract should the patient drink 300 mL Baro-Cat® approximately 2 hours before and an additional 300 mL approximately 15 minutes prior to the CT scan. For total bowel opacification the patient should drink additional 300 mL the night before the examination. If rapid transit is desired, administer the suspension chilled. Rectally administered the contrast agent should be at room temperature to body temperature.

The bisecting angle technique (or bisect angle geometry) is used for radiographic examinations of the teeth. The central axis of the x-ray beam is positioned at right angles to a plane determined by bisecting the angle formed by the long axis of the teeth being imaged, and the plane in which the image receptor is positioned behind the teeth.

See also Bitewing Radiograph.

Cheetah® is a barium sulfate suspension for use as an aid for computed tomography of the gastrointestinal tract. The contrast medium contains additional pineapple-banana flavor suspending agents, simethicone, potassium sorbate, citric acid, sorbitol, artificial sweetener and water. Individual technique will determine the suspension quantity and specific procedure used. For computed tomography of the upper gastrointestinal tract should the patient drink 200-300 mL Cheetah® approximately 30-45 minutes before and an additional 200-300 mL approximately 5-10 minutes prior to the CT scan.
For total bowel opacification an additional 250-450 mL dose of Cheetah® may be given the evening before the examination. Approximately 1-2 hours before the examination should the patient drink 250-450 mL and 5-10 minutes before the CT scan another 250-450 mL. If rapid transit is desired, the suspension can be administered chilled. Rectally use of the contrast agent should be at room temperature to body temperature.

A display is a computer monitor that shows the processed data from the scanned area. Displays can be black-and-white or color, small or large depending upon the model and price of the machine.

See also Display Field of View, Display Matrix, Window Width, Bit Range, Hounsfield Scale, Interpolation, Minimum Intensity Projection, and Printer.