Week 2 Flashcards
(24 cards)
Axial scanning is still used today for ___ imaging as it provides better image quality than helical scanning
Brain
The time delay between scans in axial scanning
Interscan delay (ISD)
Scan area of interest set by the technologist
Scan field of view
Reconstructed area seen on the image monitor
Display field of view
volumetric counterpart to pixel
voxel
___ determines the maximum number of shades of gray in the image (image contrast)
window width (WW)
The midpoint of the range of CT numbers; determines displayed image brightness
Window level
___ WL appears brighter; ___ WL appears darker
Low; high
Displays a video-like format; obtained through overlapping image sets
Cine
When considering detector efficiency, the measure of how well the detectors gather incoming photons is called:
Capture efficiency
When considering detector efficiency, the measure of how well captured photons are absorbed and converted to electrical signals is called:
absorption efficiency
In multidetector CT systems, __________ determine(s) slice thickness.
reconstruction algorithms
When considering detector efficiency, the measure of how consistently the detectors respond to similar transmitted radiation events is called:
reproducibility
In single slice CT scanning, thin collimation results in [increased/decreased] resolution
increased
The development of helical and continuous acquisition scanning was made possible by:
slip-ring technology
A typical scout length for an adult CT abdomen/pelvis scan is approximately:
550 mm
Which of the following is FALSE regarding helical scanning compared to conventional axial scanning?
helical scanning reduces the likelihood of patient motion
helical scanning allows for faster imaging
helical scanning requires more contrast material
helical scanning prevents stair-step artifacts
helical scanning requires more contrast material
Pixel size is equal to:
field of view divided by matrix size
Which of the following is FALSE regarding isotropic scanning?
it enhances 3D and multiplanar reconstructions
it reduces stair-step artifacts
it increases resolution
it is more effective with fewer detector rows
it is more effective with fewer detector rows
All of the following media forms can be used to store CT images except:
a. digital videotape.
b. magnetic disks.
c. laser optical disks.
d. VHS tapes.
D
T/F: The number of bits per pixel is the bit formation.
False; bit depth
The opening in the gantry in which the patient is positioned during scanning is called the:
gantry aperture
Which room generally houses the gantry and patient couch and should be large enough to accommodate gurneys and emergency equipment?
scanning room
The systematic method of collecting data from the patient is called:
data acquisition
