CT Flashcards
CT scans
CT number will vary according to density of tissue scanned and is a measure of how much of the x-ray beam is absorbed by the tissues at each point in the scan
Air hounsfield number
-1000 HU
Water hounsfield number
zero
Fat hounsfield number
-40 to -100
Soft tissue hounsfield number
20 to 100 hu
Bone Hounsfield number
400 to 600 H
Metal Hounsfield number
>1000 HU
Denser sustances
absorb more x-rays, less dense sunstances absorb fewer x-rays
CT scans post porcessing
CT scans can be windowed to optimize visibility if differnet types of pathology after they are attained
What disease states can you use a CT to evaluate?
Tumors
Trauma
Infections
Bleeding
CT Scan represent
a moment in time are structural not functional
Floroscopy only dymanic one
What are the limitations of CTs
- Size of patients- app 500lb max weight
- claustrophobia
- paitents that cannot hold still for extended period of time
- patient needs to hold breath for extended period
- use water-soluble oral contrast if perforation suspected aspiration concern
What kinds of contrast are there? what is it important? what are the risks?
Types- IV, enertic (oral or rectal) constrast administration
Important- Omitting constrast when it is inidcated, or giving when not, can lead to diagnostic/ treatment errors
Risk- ADR, contrast- induced nephropathy
IV contrast is
iodine based
Classification of IV constrast
High-osmoloarity contrast (not commonly used)
Low-osmolality contrast media (Most common)
Iso-somolality contrast media
