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Ultrasound Physics II > Chapter 22 Quality Assurance > Flashcards

Chapter 22 Quality Assurance Flashcards

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1
Q

Quality assurance is important because

A

It validates the consistency of images and the accuracy of devices

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2
Q

Quality assurance is

A

The routine periodic evaluation of the system to guarantee optimal image quality

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3
Q

What are the 4 quality assurance requirements

A

Repairs, Assessment of system components, Preventative maintenance, Record keeping

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4
Q

Q.A. Goals

A

Proper operation of equipment, detect changes in performance, minimize downtime, reduce the # of non-diagnostic exams

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5
Q

Q.A. Devices

A

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

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6
Q

Q.A. is based on Objective Standards:

A

unbiased, factual, repeatable

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7
Q

Tissue Equivalent Phantom involves

A

box filled with medium with same PS speed and attenuates, scatters and present echogenicities similar to soft tissue

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8
Q

embedded in tissue equivalent phantom are

A

pins, mock cysts masses

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9
Q

the T.E. phantom is used to take performance measurements and to

A

evaluated grayscale/tissue texture

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10
Q

Doppler or Flow Phantoms are used to

A

evaluate Doppler systems

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11
Q

Modern Doppler Phantoms include

A

circulation pumps which propel fluid through vessels embedded in the tissue equivalent phantom

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12
Q

Other Doppler phantoms contain

A

vibrating strings or moving belts

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13
Q

Doppler phantoms assess characteristics of

A

all doppler modalities including PW, CW, color, and power mode

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14
Q

Slice Thickness Phantom is used to

A

specifically to evaluate slice thickness which determines elevational resolution

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15
Q

elevational resolution is most likely to degrade because

A

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

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16
Q

if the slice is not thin,

A

low contrast lesions can not be seen or cystic structures may appear filled in

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17
Q

A scattering plane in an anechioc medium is imaged at either ____ or ____ degree angle

A

45 or 90

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18
Q

The display of a Slice Thickness Phantom demonstrates

A

the beam geometry or thickness

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19
Q

Phantoms are used to

A

take performance measurements

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20
Q

Tissue Equivalent Phantom allow personnel to record

A

performance measurements

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21
Q

Performance measurement: Sensitivity is the ability of

A

the system to register low level echoes ( 2 levels are assessed – normal and maximum)

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22
Q

(performance measurement) normal sensitivity is the

A

gain, TGC, and power – where pins, cysts and masses are accurately displayed

23
Q

(performance measurement) maximum sensitivity is evaluated by

A

setting the power and amplification to maximum and determining the maximum depth of tissue

24
Q

(performance measurement) Dead zone

A

the region close to the probe where images are absent due to the time it takes to switch from transmit to receive

25
Q

(performance measurement) when measuring the dead zone

A

a shallow series of pins at the top of the device are used to determine the depth at which uniform tissue texture appears

26
Q

An increasing deeper dead zone may indicate a

A

a cracked crystal, detached backing material or longer pulse duration

27
Q

Thinner dead zones are created from

A

higher frequency probes

28
Q

(Dead zone)
An acoustic standoff

A

can be used to accurately image important superficial structures —dead zone would be at the level of the standoff

29
Q

(performance measurement)
Registration Accuracy is the ability of

A

the system to place reflections in the proper positions

30
Q

(registration accuracy)
range or vertical depth calibration describes

A

the systems accuracy in placing reflectors at correct depths

31
Q

An error with Registration Accuracy could indicate

A

system malfunction or the PS in phantom fell off 1540 m/s

32
Q

Registration Accuracy can evaluate

A

A mode, M mode and 2D

33
Q

Horizontal calibration or registration accuracy is the ability to

A

place echoes in their correct position horizontally across the display (perpendicular to the sound beam)

34
Q

(performance measurement)
Distance Measurement Accuracy

A

the distance between 2 vertical and horizontal pins should be measured to check the digital calipers

35
Q

(performance measurement)
Focal Zone

A

the focus is adjusted ( depth and #) and the lateral resolution assessed in the region affected

36
Q

(performance measurement)
axial resolution is evaluated by

A

scanning a set of closely spaced pins positioned front to back in the beam

37
Q

(performance measurement)
lateral resolution is evaluated by

A

scanning a set of closely spaced pins positioned side by side in the beam —lateral resolution should be best at focus

38
Q

(performance measurement)
compensation operation or uniformity

A

2 same reflectors in phantom are located at different depths. —TGCs are applied to ensure equal echodensities can be displayed

39
Q

(performance measurement)
mock cysts and solid masses

A

tissue equivalent phantom is used to evaluate the dimension, texture, and fill-in of cysts

40
Q

(performance measurement)
mock cysts and solid masses

A

tissue equivalent phantom is used to evaluate the dimension, texture, and fill-in of cysts

41
Q

(performance measurement)
Display, Hardcopy Output, Grayscale dynamic range

A

power, gain, compress are adjusted and grayscale change evaluated

with monitor calibrated, the image displayed is compared against images on other output devices

adjusting contrast and brightness only affects the monitor not stored or archived images

42
Q

True Positive

A

correctly predicted disease

43
Q

False negative

A

incorrectly predicted no disease

44
Q

Comparison test compares our test to

A

the Gold Standard

45
Q

Comparison Test tells us

A

how good is ultrasound at detecting the presence or absence of disease

46
Q

gold standard is

A

a diagnostic test or invasive procedure that is nearly perfect at detecting the presence or absence of disease

47
Q

(performance measurement)
Sensitivity equation

A

TP / (TP + FN)

48
Q

(performance measurement)
Specificity equation

A

TN / (TN + FP)
the ability of the comparison test to detect the absence of disease

49
Q

(comparison test)
Accuracy is

A

the percentage of times the comparison test is right

50
Q

(comparison test)
accuracy equation

A

(TP+TN) / (TP+FP+TN+FN)

51
Q

(comparison test)
Positive Predictive Value is

A

the % of time the test correctly predicted the presence of disease relative to the total number of times the test predicted disease

52
Q

(comparison test)
Positive Predictive Value equation

A

TP/(TP+FP)

53
Q

(comparison test)
Negative Predictive Value is

A

the % of time the test correctly predicted the absence of disease relative to the total number of times the test predicted no disease

54
Q

(comparison test)
Negative Predictive Value equation

A

TN/(TN+FN)

Ultrasound Physics II (2 decks)

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