Chapter 22 Quality Assurance Flashcards by Dalila Juarez

What is quality assurance?

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

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Who is responsible for implementing a quality assurance plan?

the sonographer

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What are the 4 requirements of a quality assurance program?

assessment of system components
repairs
preventive maintenance
record keeping

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What are the goals of a quality assurance program?

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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what are the three Quality assurance devices?

tissue equivalent phantom
doppler phantom
beam profile/ slice thickness phantom

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What are the methods of quality assurance?

test under known, defined conditions
use constant instrument settings
use phantom with measurable characteristics]
image in an identical environment

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What type of information is unbiased, factual, repeatable, and able to be counted; information will be the same even from different people?

Objective standards

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What type of information is affected by opinion, belief, or assumption and will vary from person to person?

Subjective standards

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All Quality assurance programs should be based on what standards?

Objective standard

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What has features similar to soft tissue, is used to evaluate characteristics such as gray scale, tissue texture, multi-focus and adjustable- focus phased array transducers?

tissue equivalent phantom

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How are tissue equivalent phantoms similar to soft tissue?

speed of sound (1,540 m/s)
attenuation
scattering characteristics
echogenicity

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How is the gray scale evaluated in a tissue equivalent phantom?

the phantom contains structures that mimic hollow cysts and solid masses

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What is the device of choice to evaluate Doppler systems?

Flow Phantoms

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name the types of Doppler phantoms

Vibrating strings
moving belt
flow phantom

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What modalities are assessed by a Doppler phantom?

pulsed wave doppler
Continuous wave
Color
Power mode

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Slice thickness determines______

Elevational resolution

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What assesses the slice thickness and its effect on image accuracy, contains a diffuse scattering plane and measures the beam perpendicular to imaging plane?

Slice thickness phantom

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What slices diminish spatial resolution and reduce the ability to visualilze small, low contrast reflectors and cystic structures may appear filled?

Thicker slices

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What is the ability of the system to display low level echoes?

Sensitivity

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What are the two forms of sensitivity?

normal

- maximum

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What is normal sensitivity?

All pins, solid masses, and cystic structures are accurately displayed
TGC and gain are adjusted to establish normal sensitivity

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Under what sensitivity should Quality Assurance assessments be made?

Normal sensitivity

What is maximum sensitivity?

Evaluated with output power and amplification:
Set to max practical levels
Maximum visualization depth is used to assess sensitivity

How can sensitivity be adjusted?

Adjust the brightness

What is the dead zone?

Region close to the transducer where images are inaccurate

What does the dead zone result from?

Transducer ringing and the time is takes the system to switch from the transmit to the receive mode

what transducers have a thinner dead zone?

Higher frequency transducers

What should be used to accurately image important superficial structures?

gel or standoff pad

What do increasingly deeper dead zones indicate?

A cracked crystal, detached backing material or a longer pulse duration

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

Registration accuracy

What describes the system's accuracy in placing reflectors at the correct depths located parallel to the sound beams main axis?

Range accuracy (vertical depth calibration)

What may be the cause of range accuracy?

- system malfunctions | - the speed of sound in the phantom is different than 1,540 m/s

Depth calibration is__________

the accuracy of reflector depth positioning in A-mode, M-mode, B-mode and 2-D imaging

What is the system's ability to place echoes in their correct position when the reflectors are perpendicular to the beam?

Horizontal calibration

What is the assessment of the measurement capability of a system?

Distance measurement accuracy

in what direction should digital calipers be measured?

Vertical and horizontal

The depth at which the intensity is the highest and the beam is the narrowest

Focus

What surrounds the focus

Focal zone

______________ resolution is excellent at the focal zone because the beam is narrow

Lateral

______ resolution uses pins that are parallel to the sound beam

Axial

the minimum distance at which two side-by-side pins are displayed as two distinct images

lateral resolution

What describes the ability of a system to display similar reflectors with echoes of similar brightness?

Compensation operation or uniformity

What is the tissue equivalent phantom used to evaluate?

dimensions, texture, and fillin of cysts

True or False | Adjusting the system's output power and amplification should produce changes in the gray scale display

True

What standard is best is used in a quality assurance program?

Objective

All of the following are characteristics of a tissue equivalent phantom except? A. speed of sound similar to that in soft tissue B. attenuation properties similar to that of tissue C. scattering characteristics similar to that of soft tissue D. density similar to that of soft tissue

D. density similar to that of soft tissue

What form of resolution is evaluated by measuring the width of reflections arising from small point targets?

Lateral resolution

What form of resolution is evaluated by visualizing closely spaced pins that are parallel to the sound beam's main axis?

Axial resolution

At what interval should quality assurance evaluations be preformed?

routinely

True or False Quality assurance evaluations of ultrasound systems can only be performed by biomedical engineers or physical scientists?

False

True or False | Proper QA programs require the assessment of every transducer used in the clinical laboratory?

True

Which of the following statements are true of a tissue equivalent phantom? A. it has the same propagation speed as that of soft tissue B. it attenuates ultrasound at a rate similar to soft tissue C. embedded in it are solid masses and cystic structures D. it is the device of choice for quality assurance studies

all are true

``` All of the following may be used to evaluate Doppler systems except? A. tissue equivalent phantom B. moving belt phantom C. vibrating string phantom D. Doppler phantom ```

A. tissue equivalent phantom

systems with dynamic receive focusing should produce ___________ reflections over a wide range of depth

narrow