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Intro > Ch. 22 Quality Assurance > Flashcards

Ch. 22 Quality Assurance Flashcards

1
Q

Quality Assurance

A

the routine, periodic evaluation of an ultrasound system to guarantee optimal image quality

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2
Q

How often should quality assurance be performed

A

periodically and routinely

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3
Q

What are the 4 requirements for a QA program?

A

-assessment of system components
-repairs
-preventative maintenance
-record keeping

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4
Q

What are the goals of a QA program

A

-guarantee proper operation of the system
-detect gradual changes
-minimize downtime
-reduce the number of non-diagnostic exams
-reduce the number of repeat scans

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5
Q

What devices are used in QA?

A

-Tissue equivalent phantom
-Doppler phantom
-Beam profile/slice thickness phantom

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6
Q

Objective standards

A

factual, repeatable, quantitative information

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7
Q

Subjective standards

A

influenced by an individual’s experiences or beliefs

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8
Q

What type of standards should be used in a QA program?

A

Objective

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9
Q

What are tissue equivalent phantoms used to evaluate?

A

gray scale, tissue texture, speed calculation, multi-focus transducers, and adjustable focus phased array transducers

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10
Q

How are tissue equivalent phantoms similar to soft tissue?

A

-speed of sound(1540 m/s)
-attenuation
-scattering characteristics
-echogenicity

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11
Q

What is embedded in a tissue-equivalent phantom?

A

structures that mimic hollow cysts and solid masses (hyper and hypoechoic)

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12
Q

What are the different types of Doppler phantoms?

A

vibrating string, moving belt, flow phantom

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13
Q

What do Doppler phantoms assess?

A

All Doppler modalities, including pulsed, continuous wave, color, ad power mode

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14
Q

Slice thickness determines…

A

elevational resolution

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15
Q

Why is slice thickness most likely to degrade image quality?

A

the imaging plane is thicker than either the beam width or the pulse length

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16
Q

What does the slice thickness phantom mimic?

A

Slice thickness

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17
Q

Thicker slices…

A

diminish spatial resolution and reduce the ability to visualize small, low contrast reflectors

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18
Q

Sensitivity

A

the ability of a system to display low-level echoes

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19
Q

What are the 2 types of sensitivity

A

normal and maximal

20
Q

Normal sensitivity settings

A

All the pins, solid masses, and cystic structures in a test phantom are accurately displayed with normal power, gain, and TGC

21
Q

What is adjusted to establish normal sensitivity?

A

Output power, TGC, and amplification

22
Q

Normal sensitivity settings should…

A

Not vary from one routine evaluation to the next

23
Q

How is maximum sensitivity evaluated?

A

With the output power and amplification of the system set to the maximum practical levels

24
Q

________ is used to assess sensitivity and should not differ from one routine eval to the next

A

Maximum visualization depth

25
Q

How else is sensitivity assessed?

A

when the sonographer adjusts the system controls to change echo brightness from barely visible to full brightness (saturation)

26
Q

Dead zone

A

the region close to the transducer where images are inaccurate

27
Q

Where is the dead zone

A

It extends from the transducer to the shallowest depth from which meaningful reflections appear

28
Q

What causes the dead zone?

A

the transducer ringing and the time it takes the system to switch from transmit to receive mode

29
Q

How is frequency related to dead zone?

A

higher frequency transducers have a thinner dead zone than lower frequency transducers

30
Q

How is the dead zone assessed?

A

The shallowest series of pins in a test object

31
Q

How can you better image superficial structures?

A

an acoustic standoff or gel pad

32
Q

What does an increasingly deep dead zone indicate?

A

A cracked crystal, detached backing material, or a longer PD

33
Q

Registration accuracy

A

the ability of the system to place reflections in proper positions while imaging from different orientations

34
Q

What is another name for range accuracy

A

vertical depth calibration, axial resolution

35
Q

vertical depth calibration/range accuracy

A

describes the system’s accuracy in placing reflectors at correct depths located parallel to the sound beam

36
Q

Horizontal calibration

A

the system’s ability to place echoes in their correct position when the reflectors are perpendicular to the sound beam (lateral resolution)

37
Q

How do we evaluate distance measurement accuracy

A

By evaluating the digital calipers in both vertical and horizontal directions

38
Q

Axial resolution is evaluated by

A

scanning sets of successively closer spaced pins within the phantom

39
Q

Lateral resolution is evaluated by

A

measuring the width of reflections on the display that are created by point targets in the phantom. This approximates the beam diameter at that depth.

40
Q

Uniformity

A

the system’s ability ability to display similar reflectors in the phantom with echoes of equal brightness

41
Q

It is important to compare the relationship between the image on the system’s screen with

A

the output display of all other devices, such as remote viewing stations

42
Q

Adjustments to output power and amplification should…

A

alter the appearance of the image on the system’s display and all output devices

43
Q

Adjustments on a single-display device (like brightness or contrast)…

A

alter the image on that device only

44
Q

minimum sensitivity

A

assess the weakest echo signal that is accurately displayed, setting system gain to minimum and then increasing until the deep rod is displayed

45
Q

What does the AIUM test object evaluate?

A

axial resolution, lateral resolution, caliper accuracy, and the dead zone

46
Q

AIUM 100 mm test object

A

fluid filled tank that has the speed of soft tissue that does not attenuate

47
Q

AIUM 100 mm test object does not evaluate

A

gray scale

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