Quality Assurance

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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


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