rad contrast HW

Why are organs and soft tissue structures often difficult or impossible to identify on plain survey films?

Density and atomic # are often similar so there’s no natural contrast. Contrast media attenuates the beam and causes a difference in density between one tissue and another.

A positive contrast appears _____________ on a completed radiograph.

White

A negative contrast appears _____________ on a completed radiograph.

Black

Give 2 examples of positive contrast.

Barium and water soluble organic iodides.

What is the contrast of choice for patients with a suspected bowel perforation? Why?

Water soluble organic iodides b/c barium is insoluble

When are the water- soluble iodides typically used?

Intravascular studies or injected into body cavities, or if a GI perforation is suspected.

Give 2 examples of a negative contrast.

Air, oxygen, nitrous oxide, carbon dioxide

What is a double contrast?

When one uses both a negative and a positive contrast. Typically, the negative goes first to avoid air bubbles.

What presenting complaints would warrant GI studies to be performed?

Vomiting/Diarrhea, constipation, melena, hematochezia, mass, abdominal pain, FP, post-abdominal trauma.

What areas/organs are evaluated for an upper GI series?

Stomach and small intestines