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Fluoroscopy
Fluoroscopy and angiography are special applications of X-ray imaging, in which
a fluorescent screen or image intensifier tube is connected to a closed-circuit
television system, which allows real-time imaging of structures in motion or
augmented with a radiocontrast agent. Radiocontrast agents are administered,
often swallowed or injected into the body of the patient, to delineate anatomy
and functioning of the blood vessels, the genitourinary system or the
gastrointestinal tract.Two radiocontrasts are presently in use. Barium (as
BaSO4) may be given orally or rectally for evaluation of the GI tract. Iodine,
in multiple proprietary forms, may be given by oral, rectal, intraarterial or
intravenous routes.. These radiocontrast agents strongly absorb or scatter X-ray
radiation, and in conjunction with the real-time imaging allows demonstration of
dynamic processes, such as peristalsis in the digestive tract or blood flow in
arteries and veins. Iodine contrast may also be concentrated in abnormal areas
more or less than in normal tissues and make abnormalities (tumors, cysts,
inflammation) more conspicuous. Additionally, in specific circumstances air can
be used as a contrast agent for the gastrointestinal system and carbon dioxide
can be used as a contrast agent in the venous system; in these cases, the
contrast agent attenuates the X-ray radiation less than the surrounding tissues.
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