special subjects
Conventional Radiography
Variations of Conventional Radiography
When the density of adjacent tissues is similar, a Radiographic Contrast Agents and Contrast Reactions is often added to one tissue or structure to differentiate it from its surroundings. Structures typically requiring a contrast agent include blood vessels (for angiography) and the lumina of the gastrointestinal, biliary, and genitourinary tracts. Gas may be used to distend the lower gastrointestinal tract and make it visible. Other imaging tests (eg, Computed Tomography (CT) , A continuous x-ray beam is used to produce real-time images of moving structures or objects. Fluoroscopy is most often used With contrast agents (eg, in swallowing studies or coronary artery catheterization) During medical procedures to guide placement of a cardiac lead, catheter, or needle (eg, in electrophysiologic testing or percutaneous coronary interventions) Fluoroscopy can also be used in real time to detect motion of the diaphragm and of bones and joints (eg, to assess the stability of musculoskeletal injuries). 