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Physics > ✅Chapter 6 > Flashcards

✅Chapter 6 Flashcards

1
Q

What is the speed of sound in soft tissue

A

1540 m/s

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2
Q

Define attenuation

A

Weakening of sound waves as they travel through tissue

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3
Q

To determine the log of a number count the zeroes. So the long of 100 would be

A

2 logs

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4
Q

Frequency and distance are ______ related to attenuation

A

Directly

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5
Q

The more decibels, the ______ amplification

A

More

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6
Q

As decibels decrease, the attenuation _____

A

Increases

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7
Q

What are the three things that contribute to attenuation

A

Reflection, scattering, absorption

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8
Q

What are the two types of reflections

A

Specular and diffuse

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9
Q

Diffuse reflection is also known as

A

Backscatter

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10
Q

What is scattering

A

When the sound hits a smaller structure and it reflects everyway irregularly

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11
Q

Absorption and scattering are ______ related to frequency

A

Directly

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12
Q

Rayleigh scattering is when the sound is spread in ____ directions after hitting a red blood cell

A

Equal

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13
Q

When some structures absorb energy, it converts it to ______

A

Heat

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14
Q

What is the main cause of attenuation

A

Absorption

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15
Q

The attenuation coefficient is measured in what

A

dB per cm

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16
Q

The attenuation coefficient is constant and is always going to be ____ the frequency

A

Half

17
Q

If we have a 7MHz transducer the attenuation coefficient is going to be ____dB/cm

A

3.5

18
Q

Blood attenuates similar to _______

A

Soft tissue

19
Q

From low to high attenuation organize the following
Muscle
Bone and lung
Soft tissue
Fat
Air
Biological fluids
Water

A

Water
Biological fluids
Fat
Soft tissue
Muscle
Bone and lung
Air

20
Q

Half value layer thickness is also known as

A

Penetration depth or half boundary layer

21
Q

Describe the half value layer thickness concept

A

This describes how far sound needs to travel to decrease by HALF his original value and it depends on the medium and frequency

22
Q

In media with HIGH attenuation, half value layer is

A

Thin
(Takes less time to attenuate and decrease to 1/2 its value)

23
Q

In media with low attenuation, half value layer is

A

Thick. Takes longer for it to attenuate to half of its original value

24
Q

Impedance is also known as

A

Characteristic impedance

25
Q

What is impedance

A

The resistance of sound traveling through a medium

26
Q

What is refraction

A

Think about the pencil in the cup
Transmission with a CHANGE in direction, only happens during oblique incidence and 2 different media

27
Q

Define sine

A

Unitless number with a value from 0 to 1

Physics (20 decks)

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