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Physics 3 > M1: Quality Assurance > Flashcards

M1: Quality Assurance Flashcards

(62 cards)

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1
Q

what is one of the primary concerns with QA

A

patient misdiagnosis if the machine is not functioning properly

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2
Q

define QA

A

program that ensures proper and consistent operation of the imaging systems

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3
Q

list some of the items that QA ensures

A 
equipment operation
gradual degradation of performance
minimizes repeat exams and machine down time
safety
cost efficiency
maintains standards
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4
Q

list the 3 people responsible for QA

A

1 physician
2 sonographer
3 service (biomed/manufacturer)

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5
Q

describe the physicians role in QA

A

Qa director

assess images for overall quality

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6
Q

describe the sonographers role in QA

A

front line worker

  • assess images for quality in the ‘front line’
  • may perform routine testing ad record keeping
  • will perform routine preventative maintenance (cleaning filters, visual inspections, wiping down machine, etc)
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7
Q

what are the 2 types of service personnel

A

1 manufacturer

2 biomedical personnel

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8
Q

describe the role of the manufacturer in QA

A

provides routine preventative maintenance and repairs equipment

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9
Q

describe the role of the biomed in QA

A

acceptance testing when a machine arrives and before it starts being used… ensures compatibility, imaging performance, power output and safety

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10
Q

in general, what does routine performance testing asses

A

image performance and changes in quality over time

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11
Q

what is the key component of a good QA program

A

record keeping…. data must be frequent and be accurately recorded

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12
Q

is it best to have the same person performing the routine performance testing on phantoms each year

A

yes, for consistency

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13
Q

what is an AIUM 100?

A

an older test device in a plastic casing w/ 0.75 mm steel rods arranged in grps…. filled w/ water, alcohol and algaecide

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14
Q

what is the downside to an AIUM 100

A

no grayscale so no attenuation (so cant test sensitivity)

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15
Q

what is an upside to an AIUM 100

A

inexpensive

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16
Q

what is a tissue equivalent phantom

A

test object that contains tissue mimicking materials

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17
Q

what are tissue phantoms made of

A

plastic case w/ a gel mixed w/ graphite powder, rod groups, solid and cystic lesions.

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18
Q

why are tissue phantoms better for testing than AIUM 100s

A

give a better approximation of clinical perforance, since they allow for grayscale, attenuation, and speed of sound

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19
Q

what is the downside to tissue phantoms

A

expensive

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20
Q

list the 4 items that an AIUM test object can test for?

A

dead zone
axial/lateral resolution
depth calibration accuracy
length calibration accuracy

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21
Q

list some of the items that a tissue phantom can test for

A

all the same things as a test object plus….

elevational resolution
TGCs/attenuation/depth penetration
uniformity
sensitivity
dynamic range
contrast resolution
lesion (cystic/solid) detection
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22
Q

a good phantom must have what 5 characteristics that are similar to soft tissue

A 
attenuation coefficient
speed of sound
backscatter coefficient/relative contrast
elasticity
thermal properties
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23
Q

describe the dead zone

A

area right at the surface of the probe in the near field, also know as the main bang artifact

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24
Q

how do we test the dead zone

A

imagine the dead zone pins close to the surface of the probe and looking for changes over time

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25
why are the dead zone pins offset in tissue phantoms
to avoid reverberation artifact from the metal pins
26
how do we test for axial resolution in tissue phantoms
measure the smallest visible separation b/w the axial resolution pins and various depth (size A grp b)
27
how do we test for lateral resolution in tissue phantoms
measure the lateral resolu. pins.... the results will depend on depth and focal placement since the best lat resolu. is at the focal point (side A, grp c)
28
how do we test for elevational resolution in tissue phantoms
can test qualitatively or quantitatively..... 1. quantitative assessment requires a different type of phantom w/ a ramp... specifically a spherical void phantom or beam profile phantom to get specific measurements 2. qualitative assessments can be made w/ the TE phantoms (place focus at structure, if resolved, z axis is probably fine... scan side A, grp e)
29
how do we test for distance accuracy in tissue phantoms
measure pins at a known distance (vertically and horizon.) and compare the value you get to the true distance (side A, grp d for horiz. side A, grp c for verti.)
30
for distance accuracy, is is more important to measure small or larger distances why
larger distances, to detect smaller margins of error and enhance the % error
31
how do we test for TGC accuracy
capture images using different slide pods under different conditions and compare over time
32
what does image uniformity test | and what does it look for (list some examples)
tests a linear array consistency along the array looking for inhomogeneous regions/non uniformity... vertical band, reverberations, horizontal band
33
what does sensitivity test
the ability to detect weak echos
34
what is a common technique used to test sensitivity
maximum depth of visualization
35
what is maximum depth of visualization
power and gain are optimized for penetration and the observer records the depth where the brightness starts to fade
36
what does dynamic range control
contrast resolution
37
is testing dynamic range a subjective test
yes because you compare images over time and decide if there is a change in the display
38
why is too little contrast resolution bad
you'll have poor tissue differentiation because of poor contrast resolution
39
why is too much contrast resolution bad
you cant tell the similar shades of grey apart and they are grouped together
40
how is dynamic range tested
compared lesions of similar echogenicities and different sizes, at different depth and see if you can resolve them as separate from surrounding tissue
41
another name for dynamic range
compression
42
what does contrast resolution allow us to test
allows us to measure how well we can detect small lesions w/ a variety of appearances (solid, cystic, echogenic) etc.) while varying the settings
43
what is registration
an old test for static B scanners that ensures the arm positioning is accurate for reconstructing an image
44
how do we test registration
scan pins from 3 sides and see if the lines intersect at one point
45
2 types of doppler phantoms | what is the difference b/w them?
1. Flow 2. String or belt how the doppler shift is created
46
which type of doppler phantom matches the clinical experience what is its downside
flow or TE phantom expensive
47
describe a string or belt doppler phantom what is its upside
they move a string or belt in a water bath | dont match clinical experience but cheap
48
flow doppler phantoms can be used to measure which factors
``` maximum depth (how deep can you pick up colour flow) gate position accuracy volume flow and velocity accuracy colour flow penetration Image congruency ``` all gray scale components since it has tissue mimicking material
49
how many scan lines does the probe need to send out for colour doppler
minimum 3 scan lines to get a mean... that's why frame rate goes down so much
50
how many scan lines does the probe need to send out for 2D imaging
1 scan line
51
what is an output testing device
a device used by service personnel or manufactures to evaluate the systems power output
52
3 output testing devices, which is the most common
hydrophone power (force) balancers calorimeter
53
what are 4 features of a hydrophone
plotter spectrum analyzer oscillosope schlieren system (acousitc optical method)
54
what is plotter
small device the can plot the different intensities found along the beam (SP and SA) and produce a beam profile
55
what is a hydrophone
``` small transducer (1mm face) that produces a voltage based on the received acoustic pressure waves from the US beam (placed in the path of the beam) has piezoelectric properties ```
56
when a hydrophone is used w/ an oscilloscope, what can it measure
``` SPL PD PRP PRF DF ```
57
when a hydrophone is used w/ a spectrum analyzer, what can it measure
resonant frequency bandwidth fractional bandwidth Q factor
58
what are power (force) balancers used to measure how do they work
acoustic power have a 'scale' attached to a sound absorbing block, the more power coming out of the probe, the more the block is pushed down and the more the scale will tip upwards...more tipping = stronger intensity
59
what is a calorimeter
'heat meter' used to measure acoustic power | it contains a sensitive thermocouple the detects temp changes and can determine acoustic power
60
If calorimeters are measuring heat, this means they are measuring which attenuation process?
Absorption
61
What does image congruency test
that colour flow is accurately displayed on the screen
62
Another name for scale
Velocity range

Physics 3 (5 decks)

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