Quality Assurance
Target visualization
-depends on tvx f -spl -focusing
Scan phantom
-grayscale -targets circular, sharp edges -degree of brightness ranging up and down contrast
axial-lateral targets
-scan all 4 phantom surfaces -all targets should be visualized
pins-myofilament
.12mm
The attenuation coefficient for the 539 phantom is
.5 dB/cm/MHz
What is the common attenuation rate of tissue-mimicking material?
0.7 dB/cm-MHz
Best axial & lateral resolution that can be measured is
1.0mm on 539 Phantom
pin furthest from surfaace
10mm
vertical space
10mm
The 539 multipurpose phantom has ___ axial-lateral resolution pins
11
Observe pins DO NOT overlap
11 pins 5 to 1 mm spacing
The Model 539 US Phantom has a velocity calibration of __________m/sec
1450
The velocity of sound within the QA phantom is assumed to be
1450 to 1540 m/sec
The smallest pin separation that can be measured with the 539 phantom is
1mm
horizontal space
20mm
pin closest to surface
2mm
Scattering plane
45 degree slice thickness
Beam profile
90 degree
Compared with tissue-mimicking phantoms, what is the disadvantage of urethane rubber-based phantoms?
Acoustic velocity less than soft tissue
What is a characteristic of tissue-mimicking phantoms?
Acoustic velocity of 1540 m/s
What change in operator controls would most likely cause the maximum depth of visualization to decrease from the previous measurement performed three months ago?
Decreased transmit power
Quality control testing with a tissue-mimicking phantom yields an error in horizontal distance measurement. What is the most likely cause for this discrepancy?
Defective autoscanning
Which parameter of performance is measures with a tissue-mimicking phantom?
Distance accuracy
How often should the transducer acoustic surface and housing be inspected for damage?
Each day of use
What device measures acoustic pressure?
Hydrophone
Compared with tissue-mimicking phantoms, what is the advantage of urethane rubber-based phantoms?
Long lifetime
Which quality control test is considered an essential component of monitoring B-mode scanner performance?
Maximum depth of visualization
What component of the B-mode scanner is evaluated using the SMPTE test pattern?
Monitor
What is the dead zone for a B-mode transducer?
Region near the transducer where displayed data fails to correlate with tissue
What test apparatus enables performance evaluation of the monitor?
SMPTE test pattern
Velocity 1450m/s attenuation .05dB
Same settings
Maximum depth of visualization is an indicator of ________?
Sensitivity
What type of objects can be placed in tissue-mimicking material to facilitate the measurement of the maximum depth of visualization?
Small diameter hypoechoic spheres
Who should routinely perform quality control testing of the B-mode scanner?
Sonographer
What is a potential cause for sudden increase in the dead zone depth of a B-mode transducer?
Switching frequency from 4 to 5 MHz
What test apparatus is used to measure axial resolution?
Tissue-mimicking phantom
Which quality control test is considered an essential component of monitoring B-mode scanner performance?
Uniformity
Quality control testing with a tissue-mimicking phantom yields an error in vertical distance measurement. What is the most likely cause for this discrepancy?
Velocity calibration does not match velocity in phantom
_______ and ________ measurements can be obtained from the same image
Vertical,horizontal
A vertical black line on the US display monitor could be casused by:
a bad transducer element
Sensitivity
ability to detect & display weak echoes from small objects at specified depths(penetration)
One of the qualities that an ultrasound phantom must possess for best QA is
accurate sound velocity
Image unifromity
all similar reflector targets have same brightness
System sensitivity is performed by having the depth setting
at the maximum depth
A sonographer's QA establishes the ________ _______
baseline values
The greatest factor that influences the side to side phantom pins measurement is
beam width
A doppler QA check of Image Congruency would be to insure that:
color conforms to the vessel lumen
The transducer used for quality assurance testing is the
commonly used transducer
Gray scale quality assurance evaluation is an evaluation of
contrast differences of displayed objects
Increasing transmitter power _____ axial resolution
decreases
The best lateral resolution should correspondto
depth of focal carot
Vertical distance is measured according to the
elevational plane
Measuring multiple vertical pins in the QA phantoms important because
errors are greaterwith longer distances
Errors in vertical measurements can be caused by
excessive pressure on the phantom
Horizontal distance is measured _____ to the beam axis
horizontal
An example of a daily quality assurance check would be:
inspection of cords and probes
Gray scale & Dynamic range
just noticeable to maximum brightness, circle should appear with clear sharp edges circular
The phantom image in the heading of the first page of the SC lesson is measuring:
lateral resolution
When scanning the phantom which of the following varies throughout the field of view?
lateral resolution
near field pins
linear array
Sensitivity is performed at _____ depth
max
Sensitivity is related to
max depth of visualization
Which of the QA parameters would it be okay if the results changed with the transducer frequency?
maximum depth of visualization
A regular ultrasound QA program is usually performed
monthly
deeper pins
phased array
Quality assurance for Sensitivity should be done with maximum __________ and maximum __________.
power, gain
The recorded ultrasound images should be very ________ of the images on the US mointor
representative
Which of the following is not an assumption for the display of ultrasonic images?
scattered energy is eliminated by the transducer
Who should perform the routine QA functions?
sonographer
QA test provide objective assessment of instrument _______ and __________
stability,performance
Maximum depth of penetration would be affected by the
the frequency of the transducer
If the phantom's sound velocity was 1400 msec
the pins would be displaced deeper in the image
The dead zone evaluation is for the depth that the transducer-machine cannot process the data quick enough to display below that depth
true
The uniformity evaluation is to ensure
uniform echo brightness throughout the field of view
Sensitivity is an ultrasound machines ability to detect:
weak echoes