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Flashcards in Imaging of the Abdomen 1 Deck (15)
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What does the absorption of an x-ray beam in tissue depend on?

The thickness of the tissue, the density of the tissue and the atomic number of the tissue


What is the order of structures in the body from least absorptive to most absorptive?

Air, fat, soft tissue, bone


What is the atomic number of some different elements in the body?

hydrogen -1, carbon - 6, oxygen - 8, calcium -20, tin - 50


To what power does the atomic number influence absorption?

to the 4th power


How does introducing a contrast medium change an x-ray?

makes the structure more opaque


What contrast medium is used to look at the bowels?

A barium meal or enema


What is an endoscopic retrograde cholangio-pancreatography?

A contrast to look at the bile and pancreatic ducts


What is a percutaneous transhepatic cholangiography?

A needle of contrast injected into the bile duct


Why do the kidneys look more opaque with an iodine intravascular contrast medium?

Because the kidneys concentrate the contrast


What is an angiography?

An intra-arterial contrast


What is an intravenous contrast with biliary excretion?

Where the contrast is tagged with something similar to bilirubin so is excreted by the liver - used to see the gall bladder and bile duct


What is the hounsfield scale?

A scale to quantitatively describe radiodensity


What is radioisotope imaging?

Where radioisotopes are attached to particular molecules and introduced to the body and then emit gamma rays which are picked up by a camera


Why is a gel required in ultrasound?

To exclude air


What is the doppler effect?

A change in frequency when there is relative movement between source of wave and observer of wave - allows you to look at blood flow in an ultra sound