Ch. 22 Quality Assurance

Question 1

Quality Assurance

Answer 1

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

Question 2

How often should quality assurance be performed

Answer 2

periodically and routinely

Question 3

What are the 4 requirements for a QA program?

Answer 3

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

Question 4

What are the goals of a QA program

Answer 4

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

Question 5

What devices are used in QA?

Answer 5

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

Question 6

Objective standards

Answer 6

factual, repeatable, quantitative information

Question 7

Subjective standards

Answer 7

influenced by an individual’s experiences or beliefs

Question 8

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

Answer 8

Objective

Question 9

What are tissue equivalent phantoms used to evaluate?

Answer 9

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

Question 10

How are tissue equivalent phantoms similar to soft tissue?

Answer 10

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

Question 11

What is embedded in a tissue-equivalent phantom?

Answer 11

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

Question 12

What are the different types of Doppler phantoms?

Answer 12

vibrating string, moving belt, flow phantom

Question 13

What do Doppler phantoms assess?

Answer 13

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

Question 14

Slice thickness determines…

Answer 14

elevational resolution

Question 15

Why is slice thickness most likely to degrade image quality?

Answer 15

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

Question 16

What does the slice thickness phantom mimic?

Answer 16

Slice thickness

Question 17

Thicker slices…

Answer 17

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

Question 18

Sensitivity

Answer 18

the ability of a system to display low-level echoes

Question 19

What are the 2 types of sensitivity

Answer 19

normal and maximal

Question 20

Normal sensitivity settings

Answer 20

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

Question 21

What is adjusted to establish normal sensitivity?

Answer 21

Output power, TGC, and amplification

Question 22

Normal sensitivity settings should…

Answer 22

Not vary from one routine evaluation to the next

Question 23

How is maximum sensitivity evaluated?

Answer 23

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

Question 24

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

Answer 24

Maximum visualization depth

Question 25

How else is sensitivity assessed?

Answer 25

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

Question 26

Dead zone

Answer 26

the region close to the transducer where images are inaccurate

Question 27

Where is the dead zone

Answer 27

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

Question 28

What causes the dead zone?

Answer 28

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

Question 29

How is frequency related to dead zone?

Answer 29

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

Question 30

How is the dead zone assessed?

Answer 30

The shallowest series of pins in a test object

Question 31

How can you better image superficial structures?

Answer 31

an acoustic standoff or gel pad

Question 32

What does an increasingly deep dead zone indicate?

Answer 32

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

Question 33

Registration accuracy

Answer 33

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

Question 34

What is another name for range accuracy

Answer 34

vertical depth calibration, axial resolution

Question 35

vertical depth calibration/range accuracy

Answer 35

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

Question 36

Horizontal calibration

Answer 36

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

Question 37

How do we evaluate distance measurement accuracy

Answer 37

By evaluating the digital calipers in both vertical and horizontal directions

Question 38

Axial resolution is evaluated by

Answer 38

scanning sets of successively closer spaced pins within the phantom

Question 39

Lateral resolution is evaluated by

Answer 39

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.

Question 40

Uniformity

Answer 40

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

Question 41

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

Answer 41

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

Question 42

Adjustments to output power and amplification should...

Answer 42

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

Question 43

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

Answer 43

alter the image on that device only

Question 44

minimum sensitivity

Answer 44

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

Question 45

What does the AIUM test object evaluate?

Answer 45

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

Question 46

AIUM 100 mm test object

Answer 46

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

Question 47

AIUM 100 mm test object does not evaluate

Answer 47

gray scale