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Ultrasound Physics > Cpt 10 Notes > Flashcards

Cpt 10 Notes Flashcards

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1
Q

Describes the detail that is displayed an determines the image accuracy

A

Resolution

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2
Q

More/better/higher resolution means a _________ picture.

A

More accurate

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3
Q

Types of resolution:

A

Axial
Lateral
Temporal
Elevational

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4
Q

The ability of the system to display 2 structures parallel to the sound beam’s axis is ______

A

Axial resolution

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5
Q

Shorter pulses= _______ image quality

A

better

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6
Q

Axial resolution units:

A

mm (any distance)

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7
Q

Axial resolution is determined by:

A

SPL (medium and source) & PD

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8
Q

Axial resolution synonyms:

LARRD

A 
Longitudinal
Axial
Range
Radical
Depth resolution
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9
Q

Is axial resolution adjustable?

A

No. SPL is fixed, therefor axial resolution is fixed.

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10
Q

Axial resolution typical values:

A

10 to 1.0 mm (Less is better)

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11
Q

Long SPL= _______ axial resolution

A

Bad

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12
Q

Short SPL= _______ axial resolution.

A

Good

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13
Q

Axial Resolution formula:

A

AR=SPL (mm)/2

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14
Q

Spatial pulse length formula:

A

Wavelength (mm) x # of cycles in pulse

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15
Q

Axial resolution in soft tissue formula:

A

AR (mm)=0.77 x # of cycles in pulse/Frequency (MHz)

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16
Q

What is determines by the pulse length?

A

Axial resolution

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17
Q

Two factors that help create short pulses:

A

Less ringing

Higher Frequency

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18
Q

What causes shorter pulses in a transducer because of less ringing?

A

Backing material

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19
Q

What creates short pulses because the wavelength is shorter?

A

Higher frequencies

20
Q

When a pulse has fewer cycles in it, it is short and this is known as _________.

A

Less ringing

21
Q

(AR)

Long pulse= _________=__________

A

More ringing

Poor axial resolution

22
Q

(AR)

Short pulse= _________=___________

A

More ringing

Poor axial resolution

23
Q

(AR)

Low frequency=____________=___________=__________

A

Long wavelength
Long pulse
Poor axial resolution

24
Q

(AR)

High frequency= _________=__________=___________

A

Short wavelength
short pulse
Improved axial resolution

25
Q

Better axial resolution is seen with:

A 
Shorter SPL
Shorter PD
Higher frequencies (shorter wavelengths)
Fewer cycles per pulse (less ringing)
Lower numerical values
26
Q

The amount of detail or accuracy when reflectors are perpendicular to the sound beam is _______

A

Lateral resolution

27
Q

Lateral resolution units is ___

A

mm (any distance)

28
Q

Lateral resolution is determined by:

A

Width of beam

29
Q

Lateral resolution synonyms:

LATA

A

Lateral
Angular
Transverse
Azimuthal

30
Q

Lateral resolution formula:

A

Lateral resolution (mm)=beam diameter (mm)

31
Q

Higher frequencies will improve both ________ and ________ resolution

A

Axial

Lateral

32
Q

(LR)

Higher frequency=______ pulse length =_________ axial resolution

A

Short

Better

33
Q

(LR)

High frequency=_______ beam divergence=______ lateral resolution (in the far field)

A

Less

Better

34
Q

Lateral resolution is best with _____

A

narrowest beam

35
Q

Lateral resolution changes with ______, best at ______.

A

Depth

focus

36
Q

Axial resolution is beast in the near field with __________ and best in the far field with _________

A

Shortest pulse

Shortest pulse

37
Q

Lateral resolution is best in the near field with _________ and best in the far field with _______

A

Smallest diameter crystal

Largest diameter crystal

38
Q

Three methods for focusing:

A

External
Internal
Phased array focusing

39
Q

External focus is fixes which means ________.

A

It cannot be changed

40
Q

External focusing is achieved by placing a ______ in front of the PZT crystal.

A

Curved lens

41
Q

Internal focusing is fixed meaning that ______.

A

It cannot be changed

42
Q

Internal focusing is achieved by creating a PZT crystal with a _______.

A

Curve

43
Q

Electronic focus is ________, meaning that it can be changed.

A

Dynamic

44
Q

Electronic focusing is only seen in transducers that have _______.

A

Multiple elements

45
Q

Electronic focusing is achieved by __________.

A

Creating a delay in the excitation of each element.

46
Q

What happens when a sound beam undergoes focusing?

A

Near zone diameter is less
The focus is closer to the transducer
More widening in the far field
The focal zone size is reduced

Ultrasound Physics (30 decks)

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