Radiology lecture 4: CT Flashcards
What’s the ring of the CT machine called
The gantry
What’s another way to describe “increased attenuation” and how does it look?
Hyperdenisty
Whiter
What’s another way to describe “decreased attenuation” and how does it look?
Hypodensity
Darker
How do we view axial scans?
As though we’re looking from the foot of the bed
How are coronal scans displayed?
As through we’re looking at the patient.
What unit are attenuation values measured in?
Hounsfield Units
What’s the window level?
The centre of the selected window
What does “C30, W130” mean?
The window level is at 30 HUs (“centre”), and there’s a narrow window (“?width”) of 130 HUs
What are the 2 main groups of contrast agents?
IV
Gastro - oral or PR
Positive agents appear ______ on CT?
Hyperdense (white)
A scan with IV contrast is called a:
Contrast enhanced scan
What are some clues that IV contrast has been given?
Vessels are more dense than muscle or brain
Kidneys are more dense than muscle OR the urinary system will be dense
If you scan early after IV contrast injection, which vessels are whiter? What’s this called?
Arteries
“Arterial phase”
If you scan 15-20s after IV contrast injection, which vessels are whiter? What’s this called?
Veins
“Venous phase”
What are the 3 phases of contrast enhancement?
Arterial
Venous
Late
