CT Notes PDF

LECTURE ONE: basics of CT - Advantages of CT: eliminates superimposed structures (separate), ability to differentiate small differences in density of anatomic structures and abnormalities, super quality of images - CT analogy: images are cross-sectional, a loaf of bread. It...

LECTURE ONE: basics of CT - Advantages of CT: eliminates superimposed structures (separate), ability to differentiate small differences in density of anatomic structures and abnormalities, super quality of images - CT analogy: images are cross-sectional, a loaf of bread. It only shows parts of anatomy imaged at a particular level. Thickness is referred to as its z-axis, width is x (R/L), height is y (A/P). - pixel= picture element - voxel= collected 3D data, volume element - Positioning for a scout: set up couch zero point, and set start location. Set zero of the couch to that location (internal or external landmarks) - Production of a scout: set up tubes and detectors to produce the desired projection - ODM setup: Z-axis only, max # is one per group, indicated on kV/mA control selection (reduce dose) - - Scan field of view (SFOV): the parameter that determines how much anatomy is scanned. Should just exceed the dimensions of anatomy 30 HU - immediately after injection contrast, not in venous system yet - Arterial phase 2. Non-equilibrium 10-30 HU - contrast still mostly in arterial system now arriving to venous - After -1min = venous phase 3. Equilibrium