QC Flashcards
an analysis of the homogeneity of the detector field
flat field uniformity
a measure of image sharpness
modulation transfer function MTF
a measure of the detectors ability to distinguish differences between an objects signal in the image and the image noise corruption
contrast to noise ratio CNR
compares the level of the desired signal to the level of background noise
signal to noise ratio SNR
a higher signal to noise ratio SNR provides a _____ image
better
the ability of an imaging system to distinguish similarities of objects in an image
contrast resolution
purpose is to assure image quality due to xray imaging system is at optimum level
phantom image quality
frequency of phantom image QC
weekly
phantom image QC performance criteria
mAs=
optical density=
15%
1.40 and higher
correction action of phantom image QC
must pass to do clinical images; immediate action
phantom image QC
full point for fiber=
> =8mm
phantom image
3 test objects
fibers
speck groups
masses
phantom image
number of fibers, speck groups and masses
6,6,6
phantom image must score:
2 fibers, 3 speck groups, 2 masses
purpose is to make sure the indicated thickness is within tolerance
compression thickness indicator
frequency of compression thickness indicator
monthly
compression thickness indicator QC-
how many pounds of compression
15
compression thickness indicator performance criteria- must be accurate within
0.5cm
compression thickness indicator corrective action
must be corrected within 30 days
purpose is to assure that the mammographic xray system indicator lights, displays, and mechanical locks and detents are working properly and that the system is mechanically safe
visual checklist
frequency of visual checklist
monthly
corrective action of visual checklist
critical items-fixed before clinical use
less critical items-fixed within 30 days
3 critical items on the visual checklist
cleaning solution, locks working, paddles/face shield have no cracks, breast support has no cracks
purpose is to ensure free of any marks that can interfere with clinical info, make sure monitors are calibrated and meet manufacturers specs
acquisition and radiologist workstation monitor QC
frequency of acquisition and radiologist workstation monitor QC
monthly
acquisition and radiologist workstation monitor QC test pattern
society of motion picture and television engineers SMPTE
corrective action for acquisition and radiologist workstation monitors
within 30 days
purpose is to ensure viewing conditions for the radiologist are to the full potential without degrading the images on the monitor
acquisition and radiologist workstation monitor cleanliness
frequency for acquisition and radiologist workstation monitor cleanliness
once a day
performed to check communication between the entities of the detector, printer and monitors.
SMPTE
acquisition and radiologist workstation monitors minimum luminance resolution
8 bit
purpose to determine the number and cause of repeated digital mammograms. analysis of this data can help identify ways to improve system efficiency and reduce digital retakes and patient exposure
repeat analysis QC
frequency of repeat analysis
as much as needed; quarterly
performance criteria of repeat analysis
below 2%
purpose is to assure that the mammographic system can provide adequate compression in power driven and manual modes and that the equipment does not allow too much compression to be applied damaging patients breast tissue
compression force
frequency of compression force
semiannually
performance criteria of compression force QC in lbs
25-45
corrective action for compression force QC
before clinical use
purpose is to assure that the system is calibrated properly and to erase artifacts and errors
manufacturer detector calibration
frequency of manufacturer detector calibration
weekly
equipment needed for manufacturer detector calibration
flat field phantom
corrective action for manufacturer detector calibration
before clinical use
to make sure the images are free of undesirable artifacts
artifact evaluation
to ensure that the image quality of the system is maintained at optimal levels
SNR and CNR QC