Transducers III Flashcards

1
Q

The beam diameter is equal to the width of the?

A

crystal

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2
Q

The near zone is also called?

A

Fresnol zone

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3
Q

The far zone is also called?

A

Fraunhofer zone

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4
Q

At one NZL the beam diameter is equal to?

A

1/2 transducer diameter

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5
Q

At 2 X NZL the beam diameter is equal to?

A

transducer diameter

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6
Q

Focusing only occurs in which zone?

A

Near zone

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7
Q

Formula for NZL of a nonfocused beam

A

d^2 / 4x wavelength OR d^2 x F/6

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8
Q

Range is also called?

A

time of flight or go-return time

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9
Q

Equation for time of flight

A

T= 2D/C

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10
Q

what is time of flight

A

amount of time amount of time it takes echo to travel into patient

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11
Q

What is the microsecond rule

A

for every 1 cm it takes 13 microseconds to travel

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12
Q

True or False: A focused beam produces a stronger echo than an unfocused beam

A

True

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13
Q

Focusing improves _______ and ________

A

lateral resolution; transducer sensitivity

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14
Q

What are the two types of mechanical focusing?

A

External and internal

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15
Q

External focusing

A

adding lens or mirror

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16
Q

Internal focusing

A

adding a curved element

17
Q

Huygen’s principle

A

pattern from group of crystals is the summation of all wave patterns

18
Q

Two types of electronic focusing

A

transmit (variable) and receive (dynamic)

19
Q

Which type of electronic focusing is under the sonographer’s control?

A

transmit (variable)

20
Q

Increasing the number of focal zones will decrease ?

A

the frame rate

21
Q

What helps restore frame rate?

A

co-processing

22
Q

Which type of electronic focusing is not under the sonographer’s control?

A

Receive (Dynamic)

23
Q

Beam divergence depends on?

A

transducer diameter and frequency

24
Q

Crystal diameter and beam divergence are _______ related

25
Q

Beam divergence and frequency are ________ related