GI imaging Flashcards
Who invented X-rays?
Wilhelm Roentgen
What determines the absorption of X-ray beams?
Thickness of tissue
Density of tissue
Atomic number
How much affect does the atomic number of the substance have?
The 4th power
Which absorbs more X-rays, fluids or fat?
Fluids
How do you improve X-ray sensitivity?
Add contrast
Use a more sensitive method (CT)
What is a barium enema?
Retrograde introduction of barium into the system
What is an endoscopic retrograde cholangio-pancreatography?
Insert an endoscope down the GIT until you reach the major duodenal papilla then squirt contrast fluid up it
What is a percutaneous transhepatic cholangiography?
Procedure where a needle is inserted, goes through the liver and into the bile duct where contrast is injected
Which compound do you use for intravenous/intra-arterial contrast?
Iodine (53)
How long after intravascular contrast administration will it be seen in the kidneys?
30 minutes
What happens when contrast is tagged with a bilirubin like compound?
It is metabolised in the liver
What is a houndsfield unit used for?
CTs
What is radioisotope imaging?
Intravenous administration of tagged molecules that target a certain organs and emit gamma rays, these are recorded using a camera
What is the frequency and wavelength of ultrasounds?
High frequency
Short wavelengths
Why is gel required in ultrasounds?
Exclude air
