CT Sim Flashcards
ct external gantry components
couch, tilt, emerg off buttons, lasers
internal ct components
detector array, x-ray tube
ct info recorded by
solid state image detectors or gas filled detectors
ct ray is the part of the beam that
falls on one detector
ct view is one complete translation generating ?
profile or projection
ct image matrix is an image displayed in
rows & columns
ct pixel is each cell on the image
matrix
ct voxel is each
pixel & slice thickness or volume
ct filter back projection is summation method of
reconstructing data; avg linear attn coefficient per pixel
ct pitch is the distance traveled by
couch during x-ray tube rotation
in inverse planning, planner specifies
desired dose limits & computer produces plan
ct contrast is shades of
grey
beam hardening artifacts appear and are where
dark bands often near bone
ring artifact appears if what’s not working
detector
motion artifact appears as
streaks or less resolution or partial volume artifact
helical artifact appears as
object shape distortion
ct window width (WW) is a range of
’s displayed or the contrast
ct window level (WL) represents
central HU of all CT #s w/i the WW
incr WW, ? contrast
decr
decr WW, contrast
incr
incr WL= ? image
darken
decr WL= ? image
brighten
dicom stands for
digital imaging & communications in medicine
scintillation detector contains ? assemblies
crystal photodiode assemblies
ct crystal of choice
CdWO4 (Cadmium Tungstate)
narrow WW= ? contrast on DRR
incr
projection is an intensity pattern created from
linear attn coefficient
average ct dose per CT slice ?
1-6 cGy
EPID components
cathode tube/tv monitor, charged couple device/TV camera, metallic fluoro screen
ct # fat
-100
ct pitch determines closeness of
helix
high matrix= ? pixel
small
small pixel= ? resolution
high
high resol= ? noise
high
small pixel size = ? noise
more
incr mA= ? noise
less
incr kvp= less
noise
incr FOV= ? noise
less
incr pixel size= less
noise
incr thickness= ? noise
less
ct window level changes
density
