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Physics > Chapter 22 > Flashcards

Chapter 22 Flashcards

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1
Q

Quality assurance

A

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

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2
Q

Time interval for QA

A

Time interval depends on clinical circumstances but must be done routinely.

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3
Q

Is QA a medical and legal necessity for every imaging facility

A

Yes

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4
Q

Assessment of system components include

A

Repairs,
Preventative maintenance,
Record keeping

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5
Q

Who is responsible for QA

A

Sonographers

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6
Q

Goals of Quality

Assurance

A

Guarantee proper orientation 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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7
Q

Methods for Quality

Assurance

A

Test under known, defined conditions.
Use constant instrument settings,
Use a phantom with measureable characteristics,
Image in an identical environment

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8
Q

completely unbiased, factual, repeatable, able to be counted.

A

Objective

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9
Q

Objective is

A

The same, even when obtained by different people

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10
Q

influenced by an individuals experiences or beliefs, cannot be verified using concrete facts or figures, affected by opinion.

A

Subjective

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11
Q

Varies from person to person

A

Subjective

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12
Q

Quality Assurance should be based on

A

Objective standards

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13
Q

Devices for Quality

Assurance

A

Tissue equivalent phantom, Doppler phantom, beam profile/ slice thickness phantom

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14
Q

Tissue Equivalent Phantom: ultrasonic features are similar to

A

Soft tissue

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15
Q

Tissue Equivalent Phantom is used to evaluate

A

characteristics such as gray scale and tissue texture

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16
Q

Tissue equivalent phantom contains

A

Small scatterers that act like soft tissue

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17
Q

With _ phantoms nylon may be embedded into the phantom to produce reflections at strategic locations

A

Tissue equivalent

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18
Q

With _ phantoms structures that mimic hollow cysts and solid masses are also embedded into the phantom

A

Tissue equivalent

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19
Q

Tissue Equivalent
Phantom
Simulate tissue properties, allowing assessment of:

A

Detail resolution, Contrast resolution, Penetration,

Dynamic range, Time-gain compensation

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20
Q

Doppler Phantom

• Assess the characteristics of

A

All Doppler modalities •Pulsed wave
•Continuous wave
•Color
•Power

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21
Q

Doppler phantom includes a _ which propels fluid through vessels embedded in a tissue equivalent phantom.

A

Circulation pump

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22
Q

What does a circulation pump do?

A

propels fluid through vessels embedded in a tissue equivalent phantom.

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23
Q

Other Doppler phantoms contain _

A

vibrating strings or moving belts.

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24
Q

Doppler test objects and flow phantoms enable the evaluation of:

A

Spectral speed calibration, Gate location,

Penetration of spectral and color Doppler instruments

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25
Q

Slice Thickness
Phantom
assesses the

A

slice thickness and its effect upon image quality

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26
Q

_ Contains a diffuse scattering plane that is at an angle to the incident sound beam.

A

Slice thickness phantom

27
Q

Slice thickness phantom contains

A

a diffuse scattering plane that is at an angle to the incident sound beam.

28
Q

Slice thickness phantom: medium mimics _

A

Soft tissue

29
Q

Slice thickness phantom measures

A

The beam geometry perpendicular to the imaging plane

30
Q

the ability of a system to display low-level

echoes.

A

Sensitivity

31
Q

Normal sensitivity

A

settings at which all the pins, solid masses, and cystic structures in the test phantom are accurately displayed.

32
Q

Normal sensitivity: _, _ , and _ are adjusted to establish normal sensitivity

A

Output power, TGC, and amplification

33
Q

evaluated with the output power and amplification of the system set to the maximum practical levels.

A

Maximum sensitivity

34
Q

the region close to the transducer where

images are inaccurate. Extends from the transducer to the shallowest depth from which meaningful reflections appear.

A

Dead zone

35
Q

Dead zone

A

the region close to the transducer where

images are inaccurate. Extends from the transducer to the shallowest depth from which meaningful reflections appear.

36
Q

Should info from the dead zone be used in a diagnostic setting?

A

No

37
Q

Dead zone results from

A

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

38
Q

Dead zone is assessed with

A

the shallowest series of pins in a test object.

39
Q

Dead zone: _ depth at which uniform tissue texture appears in a tissue equivalent phantom

A

Shallowest

40
Q

Higher frequency transducers have a _ dead zone than lower frequency transducers

A

Thinner

41
Q

_ positioned between the transducer and the patient allows accurate imaging of important superficial structures.

A

Stand-off or gel pad

42
Q

An increasingly deeper dead zone may indicate a

A

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

43
Q

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

A

Registration accuracy

44
Q

Registration accuracy

A

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

45
Q

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

A

Range accuracy

46
Q

Range accuracy

A

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

47
Q

Range accuracy aka

A

Vertical depth calibration

48
Q

Range accuracy: Differences between the ultrasound scan and actual pin location may be caused by

A

system malfunction or the speed of sound in the phantom is different than 1,540 m/s.

49
Q

the system’s ability to place echoes in their correct position when the reflectors are perpendicular to the sound beam.

A

Horizontal calibration

50
Q

Horizontal calibration

A

the system’s ability to place echoes in their correct position when the reflectors are perpendicular to the sound beam.

51
Q

digital calipers should be checked in both vertical and horizontal directions periodically.

A

Distance Measurement Accuracy

52
Q

Distance Measurement Accuracy

A

digital calipers should be checked in both vertical and horizontal directions periodically.

53
Q

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

A

Focus

54
Q

_ zone surrounds the focus

A

Focal

55
Q

Lateral resolution is _ in the focal zone because

A

Excellent,

The beam is narrow

56
Q

The focus of phased array transducers must be

A

Carefully evaluated

57
Q

Axial resolution is evaluated by

A

scanning sets of successively closer spaced pins within the phantom.

58
Q

Axial resolution: pins are _ to the sound beam

A

Parallel

59
Q

The smallest distance at which two pins positioned parallel to the sound beam are displayed as two distinct echoes.

A

Axial resolution

60
Q

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

A

Lateral resolution

61
Q

Lateral resolution: Another method is to measure _. This approximates _

A

the width of reflections on the display that are created by point targets in the phantom.
Beam diameter at that depth

62
Q

Uniformity describes

A

the system’s ability to display similar reflectors in the phantom with echoes of equal brightness. With proper TGC, identical reflectors should have the same appearance on the monitor, regardless of depth.

63
Q

Compensation Operation or Uniformity: The system should

A

accurately display hollow structures as anechoic and solid structures as hyperechoic

Physics (25 decks)

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