QC test 1 Flashcards
Quality control is part of what kind of program?
quality assurance
what is the purpose of the QC program?
ensure that we have the best image quality
what does the SMPTE pattern test for?
what does this stand for?
what does JND stand for?
the luminance response
society of motion picture and television engineers
just noticeable difference
how do we calculate the repeat-reject rate?
what is the optimal number we like to keep this within?
what is the primary cause of repeats on DR systems?
divide total x-rays/ repeats
3-5% is where we would like to keep the repeats
patient positioning
what is a way to test the collimator alignment within x-ray? (light field to x-ray field)
A-penny test
(for collimation)
if we are testing the hardness of the x-ray beam what are we primarily looking at?
half-value layers
what is the range for SID accuracy?
2% variance
what is an acceptable range of accuracy for collimator alignment test is?
2% variance
what is the tolerance range for kVp variations?
5% range
In fluoroscopy units what is the tolerance in any one direction?
in total?
3% variance in one direction
4% total variance
what are the main components in a quality control program?
acceptance test (establish a baseline)
annual testing
diagnose & documenting deviations (for issues)
which of the following tests of QC imaging can be performed visually by a radiographer?
uniformity issues
(artifacts)
(also uneven spatial resolution or intrinsic dark noise (dark areas)
if we are doing a repeat-reject analysis what is a good percent to stay within?
3-5%
what is a primary reason we see repeats on exams? (digital)
patient positioning
(motion is on there, but not main)
what is the tolerance for a timer accuracy?
5% variance
what kind of monitors do we mainly use?
what is a disadvantage?
what is the name of this?
LCD monitors
(best for radiology)
limited view angle
VAD (viewing angle dependence)
what type of monitor or workstation is critical that the illuminance & contrast is set to a precise setting?
Class 1 monitor
(diagnostic workstation) where diagnoses are made)
how would you describe illuminance?
light that is striking the surface of an object
(coming from a source)
what is an example of a class 2 monitor?
What do we use these for?
technologist work station
(post processing & window leveling)
what do we use to measure illuminance with?
photometer
what is the least reliable exposure factor?
what is the tolerance?
MA- linearity
10% (tube fatigues)
if we are using the SMPTE test pattern and use the photometer and place it on the squares to measure the JND’s what test are we performing?
luminance response test
if we are measuring resolution within an image what does we use?
line-pairs tool
what spatial resolution should we be able to see on a monitor?
if it was done on a detector?
2.5 LP/mm
2.5 LP/mm
how often do we test lead aprons?
annually
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The actual center of the ______ must align to the centering indication within ____of the ____
x-ray beam
1%
SID
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In the case of centering, if the SID is 72 inches what would be the tolerance?
0.72 inches
(72 x 0.01)
what is the maximum exposure that can be made per minute in a non-boost situation?
what about within a boost-mode?
10R per minute
20R (big MAMA)
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what is the tolerance for centering?
what is the tolerance for SID?
what is the tolerance for exposure timer?
1% variance
2% (+/-) variance
5% (+/-) variance
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Actual SID must be within ____of the _____ SID
if the SID was 72” what would be the tolerance?
2%
indicated
1.44” (70.56-73.44)
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if the indicated SID is 60”, the actual SID should be no more than:
61.2”
(60 x 0.02= 61.2)
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the light field must align with the ____ _____ collimation within ____ of the SID
x-ray field
2%
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(t/f) the actual exposure field extends farther than the light field
and this must be within?
true
2% of the SID
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Actual exposure time must be within ____ of indicated ______ _____
5%
exposure time
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if the prescribed indicated exposure time is set at 100 ms the tolerance is?
what is the range?
5 ms
95ms-105ms
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which of these exposure timers are within acceptable limits when the exposure time on the operator’s console is set to 200 milliseconds?
A. 211 milliseconds
B. 208 milliseconds
C. 204 milliseconds
D. 192 milliseconds
E. 189 milliseconds
B,C,D
(190-210)
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what is the primary reason for AEC?
to receive adequate amount of input to prevent over/under exposure
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how do we test the accuracy of AEC?
taking multiple exposures (3) of different thicknesses of aluminum to ensure consistency
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If our first exposure results in 200 mGy with one sheet of aluminum, how much exposure dose should we have with two sheet of aluminum?
200 mGy
(AEC should remain consistent regardless of extra tissue or attenuation)
Review:
A radiography is acquired using AEC unit with an exposure setting of 200 MA and 60 kVp. If the inital receptor exposure is measured as 100 mGy, increasing the kVp by 15% will result in a receptor exposure of approximately?
A. 200 mGy
B. 115 mGy
C. 100 mGY
D. 85 mGy
c. 100 mGy
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(t/f) The AEC should always remain the same regardless of SID or part thickness
true
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For the kVp calibration the actual kVp must be within ____ of the ____ ____
5%
assigned kVp
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for the kVp calibration how much tube potential variance is allowed when the assigned technique for an exposure that is 85 kVp?
A. +/- 0.85 kVp
B. +/- 1.7 kVp
C. +/- 4.25 kVp
D. +/- 8.5 kVp
4.25 kVp
(85 x 0.05)
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when is comes to exposure reproducibility what is the tolerance?
+/- 5% variance
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If the actual kVp is higher than the assigned kVp this results in a?
over powerful & overly penetrating beam
(unnecessary increase in patient dose & can create more scatter)
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what is the tolerance for exposure linearity?
10%
(no more than this should change between mA stations)
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what is exposure reproducibility?
a measure of the exposure values when we are reproducing the exact technical settings
(same MA, same exposure time, same kVp etc)
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Exposure 1: 70 mGy
Exposure 2: 74 mGy
is this difference within the allowed tolerance?
no
(74-70) = 4 /70= 5.7 % variance
(subtract differences of the exposure then divide)
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when we are testing the exposure reproducibility should not be off by +/-
5% variance between the two exposures
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what is the main objective with exposure reproducibility?
to produce the same beam intensity with the same technical factors
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with exposure linearity we are changing the ______
exposure settings
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(t/f) the exposure per mAs should not change more than 10% between mA stations for exposure linearity
true
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what are detector calibrations?
a system to ensure the same response to the same level of radiation exposure
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(t/f) all detectors and all readers (CR) have to be calibrated the same
true
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In detection calibrations how many times do we expose?
3 times
(with same technical factors (kvp, mAs, & SID)
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what does the erasure thoroughness measure?
how is this done?
the CR readers ability to completely erase the previous image
with a small lead block (exposure then repeat)
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(t/f) The erasure thoroughness is a test done on CR readers
true
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what is plate uniformity?
ability for the receptor to read all input evenly across the surface
(should not have any changes in contrast)
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what is an example of plate uniformity failure or non-uniform?
center of image darker than the rest
artifacts (imbedded in the receptor)
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what can you test spatial resolution on?
x-ray machine
display system
or image receptor system
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how do we test for spatial resolution?
line pairs test tool
Review:
A blank exposure is made using 5 mAs and 75 kVp. If the outer edges of the receptor demonstrate increased exposure, this may be a quality control issue related to:
A. Erasure thoroughness
B. Plate uniformity
C. Spatial resolution
D. Reader calibration
B. Plate uniformity
Review:
A CR cassette is exposed using 5 mAs and 75 kVp and the resulting exposure indicator is 202. The same cassette is exposed using the same technique and processed in a different reader and the resulting indicator is 436. This is a quality control issue related to?
A. Erasure thoroughness
B. Plate uniformity
C. Spatial resolution
D. Reader calibration
D. reader calibration
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Each monitor must be calibrated to the _______
why?
DICOM grayscale standard display function (GSDF)
so it displays the image in the same way (consistency)
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