Ultrasound Physics Review 1

Front 1

Which of the following human tissues demonstrates the highest rate of attenuation of the ultrasound wave? Liver, Fat, Fulid, Lung, or Blood Vessels?

Back 1

Lung

Front 2

What property would result in increased propigation speed of a medium?

Back 2

Increased stiffness

Front 3

If sound waves of 3Mhz, 5Mhz, and 10Mhz are transmitted through the same section of liver, which frequency would reach the transducer first?

Back 3

Reflections from all three frequencies would have identical transmit times

Front 4

While preforming an ultrasound of the thyroid gland, you adjust the acoustic power by -3 dB, what would happen to the intensity?

Back 4

It would be halved

Front 5

What detrermines acoustic impedance?

Back 5

Density and propagation speed of the medium

Front 6

Which of the following is true regarding the half value (HVL) thickness for a 10Mhz transducer in soft tissue? It represents a 3dB decrease in signal intensity, it occurs at a shallower dpth than the HVL for a 5Mhz transducer, It represents the point at which the beam intensity is reduced by one half, B & C, or A & B& C

Back 6

A & B& C

Front 7

With absorption, acoustic energy is converted into what?

Back 7

Heat

Front 8

What term is used to describe the hyperechoic region region seen below a cyst?

Back 8

Acoustic enhancement

Front 9

The attenuation os ultrasound propigating through soft tissue is approx what?

Back 9

0.5 dB/cm/Mhz

Front 10

As acoustic pressure increases, so does what?

Back 10

Intensity

Front 11

As a general observation about media of concern in diagnostic ultrasound, sound propaggates faster in materials with greater what?

Back 11

Stiffness

Front 12

With specular reflection the strength of the received signal depends on what 2 factors?

Back 12

Difference in acoustic impedance and angle of incidence

Front 13

How is a longitudinal wave characterized?

Back 13

Particle motion occurring in the same direction as propagation

Front 14

You are imaging a structure that is highly attenuating, WHat effect would you expect to encounter?

Back 14

Shadowing

Front 15

Bulk modulus refers to what quality?

Back 15

Stiffness

Front 16

When your patient asks you how much longer the exam will take, his voice is in the audible frequency range. What is an audible frequency range?

Back 16

10kHz

Front 17

Which of the following frequencies is considered to be ultrasound? 2,000Hz, 20Hz, 2MHz, 200Hz, or 2Hz?

Back 17

2MHz

Front 18

What does Snell's law describe?

Back 18

The angle of sound transmission as an interface with oblique incidence and different propagation speeds

Front 19

Describe Diffuse reflection?

Back 19

A reflected beam that is scattered in all directions

Front 20

During an ultrasound examination of the aorta, a 45degree beam to vessel angle would be called what?

Back 20

Oblique incidence

Front 21

What is the period of 5MHz frequency?

Back 21

.0000002s

Front 22

What is the sped of sound defined as?

Back 22

The Speer at which the sound wave propagates through the medium

Front 23

What interaction of ultrasound and tissue is primarily respnsible for imaging the internal structure of organs?

Back 23

Scattering

Front 24

When the sound beam is refracted during an ultrasound examination, which of the following will you detect on the ultrasound image?

Back 24

Lateral Misregistration

Front 25

Which of the following terms denotes the time it takes for one cycle to occur? Frequency, Amplitude, Wavelength, Period, or Pressure?

Back 25

Period

Front 26

For distance measurement to be accurate in an ultrasound tissue phantom, the phantom sound propagation speed must be waht?

Back 26

1540m/s

Front 27

The hyperechoic region under a cycst results from what?

Back 27

Decreased attenuation through a fluid filled structure

Front 28

While preforming an abdominal ultrasound examination, you encounter the following interfaces. Which will produce the strongest reflected signal? Spleen/kidney, Liver/pancreas, Liver/Bowel gas, Liver/bile duct, Renal cortex/ renal sinus

Back 28

Liver/bowel gas

Front 29

The regions of low pressure and density that are formed during sound propagation are termed waht?

Back 29

Rarefractions

Front 30

During an abdominal ultrasound exam, you encounter all of the following interactions of ultrasound and tissue. Which of the following will not cause redirection of ultrasound energy? Reflection, Scattering, Divergence, Absorption, Refraction

Back 30

Absorption

Front 31

Which prefix equals 10-3?

Back 31

Milli

Front 32

Frequency of the ultrasound wave is defined as what?

Back 32

Number of cycles per second

Front 33

You are scanning a patient with suspected gallstones using a 3.5MHz transducer. You do not ditect shadowing distal to the suspected gallstone. What can you do to enhance the visibility of the acoustic shadow distal to a gallstone?

Back 33

Increase the transducer frequency

Front 34

According to Snell's law, the angle of transmission is related to the incident beam angle and what?

Back 34

The relative velocities of sound in the two media

Front 35

What is another term for nonspecular reflection?

Back 35

Scattering

Front 36

During the performance of an abdominal ultrasound examinatioin, you would most expect to encounter refraction in what view?

Back 36

Transverse view of the gallbladder

Front 37

What would be the result of inaging the aorta at an angle of 45?

Back 37

Tha angle of reflection will be oriented away from the transducer resulting in decreased visuaalization of the aorta

Front 38

Wavelength depends on what two factors?

Back 38

Frequency and propagation speed

Front 39

If the propgation speed is unchanged at the interface, which most correctly describes the sound tissue interaction that will take place when the ultrasound wave strikes the interface? Specular reflection, Dcattering, Diffraction, Refraction, or None

Back 39

Scattering

Front 40

When you switch from a 2.5MHz to a 5MHz transducer, what happens to the wavelength?

Back 40

It halves

Front 41

You are scanning an interface at normal incidence in which the acoustic impedance is unchanged from one media to the other. WHat will occur?

Back 41

There will be no sound reflected

Front 42

Describe sound propagation in a medium

Back 42

Molecules oscillating back and forth to propagate sound waves but does not move frorm one end of the medium to another

Front 43

For pulsed ultrasound, the following factors determine the frequency of the sound wave: Pulse repitition frequency, propagation speed of the piezoelectric material, thickness of the piezoelectric material, B & C, or A & B & C

Back 43

B propagation speed of the piezoelectric material & C Thickness of the piezoelectric material

Front 44

You have increased the transmit power while performing a pelvic ultrasound. Which actions does this increase?

Back 44

Penetration, Acoustic power, Image brightness, and the voltage applied to the crystals

Front 45

While imaginag a breast cyst, you notice shadowing posterior to each lateral border of the cyst. Wjat is the source of the shadow?

Back 45

Redirection of the sound beam at an interface with diefferent propagation speeds and a curved surface

Front 46

For soft tissue, which one of the following is responsible for determining acoustic impedance: Attenuation, Frequency, Absorption, Density, or Amplitude?

Back 46

Density

Front 47

What two conditions must be present to cause refraction of a sound wave?

Back 47

Oblique incidence and different media propagation speeds

Front 48

If the number of cycles in a pulse is increased but the wavelength remains the same, what happens to the pulse duration?

Back 48

It is increased

Front 49

The maximum cyclical change in a quantity is known as what?

Back 49

Amplitude

Front 50

What sound tissue interaction is necessary to form an ultrasound image?

Back 50

Reflection

Front 51

The transducer you are using to image the liver transmits a wide beam of 3-5MHz. Describe the beam after it has transversed the liver?

Back 51

The reflected bandwith will be shifted down in frequency due to the increased attenuation of higher frequencies

Front 52

Increasing the frequency on a multifrequency transducer from 3.5 to 5.0 MHz will do what to what wavelength?

Back 52

Decrease it

Front 53

What term is used to describe the reduction in the intensity of sound as it propagates through tissue?

Back 53

Attenuation

Front 54

Sound may be attenuated by all of the following Except: Reflection, Scattering, Conversion of sound to heat, Absorption, or Compression?

Back 54

Compression

Front 55

In sound wave propagation, the region of elevated pressure is termed what?

Back 55

Compression

Front 56

During the performance of an ultrasound exam, you decide to adjust the system parameters to improve the image. Which of the following parameters is not adjustable by operator control on ultrasound system: Frequency, Prop speed, power, intensity, or echo signal amplificaiton?

Back 56

Prop speed

Front 57

Which of the following is an example of a rayleigh scatter: Renal capsule. arterial wall, red blood cells, bowel gas, or femur?

Back 57

Red blood cells

Front 58

An echo from which of the following sound reflectors is most dependent on the angle of incidence: Rayleigh, Diffuse, Specular, Acoustic, or Nonspecular?

Back 58

Specular

Front 59

The following adjustment would decrease beam intensity: Increasing acoustic output, Decreasing receiver gain, increasing focusing, Increasing beam area, increasing amplitude

Back 59

Increasing beam area

Front 60

You are scanning a large abdominal mass that is comprised primarily of fat. What are you most likely to encounter?

Back 60

Axial misregistration of the mass on the screen caused by the slower propagation speed through fat

Front 61

What is the relationship of frequency to absorption?

Back 61

If frequency is doubled, absorption is doubled

Front 62

Which of the following tissues would have the slowest propagation speeds for sound? Fat, Blood, Muscle, Bone or Liver?

Back 62

Fat

Front 63

Relative measurement of intensity based on a logarithmic scale is expressed how?

Back 63

In decibels

Front 64

An interation of echoes that leads to reinforcement rather than to partial or total cancellation is known as what?

Back 64

Constructive interference

Front 65

WHat is the velocity of an ultrasound wave in bone?

Back 65

4080 m/s

Front 66

What is the algebraic summation of waves called?

Back 66

Interference

Front 67

What interaction is associated with divergence of the sound beam after passing through a small aperature?

Back 67

Diffraction

Front 68

During abdominal US, you image the following structures: Blood bile, Liver parenchyma, Gallstone, Spleen, which is most attenuating?

Back 68

Gallstone

Front 69

As frenquency increases what else increasees?

Back 69

Absorption, Scattering, Attenuation

Front 70

What system control should you adjust to account for sound attenuation with depth?

Back 70

TGC

Front 71

you are imaging the interface between two abdominal structures at normal incidence. They have the same acoustic impedance. What will occur at the boundary of the two structures?

Back 71

All of the sound will be transmitted

Front 72

The intensity coefficient at the interface between two structures equals 1%, What is the intensity reflection coefficient

Back 72

99%

Front 73

You are imaging an irregular round mass in the liver that has a much slower propagation speed than liver tissue, what sound tissue interaction will be encountered as the ultrasound propagates through this interface?

Back 73

Refraction, Reflection, Absoprtion, Scattering

Front 74

Which of the following factor does not affect impedance: Stiffness, Density Prop speed, Frequency or all of the above?

Back 74

Frequency

Front 75

13kHz can also be expressed as what?

Back 75

13,000 Hz

Front 76

Which of the following adjustments would reduce sound attenuation in the body most? Increasing receiver gain, Decreasing transmit power, Increasing dynamic range, Decreasing frequency, or Decreasing focus?

Back 76

Decreasing frequency

Front 77

Why is diagnostic US limited in its diagnostic application to the adult brain?

Back 77

Because the great acoustic impedance mismatch between the cranium and soft tissue causes most of the sound to be reflected at that interface

Front 78

Reflection of the sound beam from a large interface wilth a rough surface is called what?

Back 78

Diffuse reflection

Front 79

Which of the followinf interactions of sound and tissue decreases the intensity of the transmitted beam? Absorption, Reflection, Scattering, Conversion to heat, or all of them?

Back 79

All of them

Front 80

What must be present for sound reflection to occur at the interface of two structures?

Back 80

A difference in the acoustic impedance of the media

Front 81

Which of the following statements is true regarding the effect of frequency on Rayleigh scattering; The amount of scattering is not affected by frequency, Scattering intensity doubles if frequency is doubled, Doubling the freq results in halving the scattering intensity, Doubling the freq results in quartering the scattering intensity, or Scattering intensity is proportional to freq raised to the fourth power

Back 81

Scattering intensity is proportional to frequency raised to the fourth power

Front 82

What can be done to enhance visibility of a specular reflector?

Back 82

Acan with an incident angle of 90

Front 83

What is an example of a specular reflector?

Back 83

Renal capsule

Front 84

While performing a hepatic sonogram on a patient with a fatty liver, you are unable to visualize the posterior right lobe of the liver. Which of the following solutions would be most likely to enable visualization of this area: Decrease dynamic range, Decrease nearfield DGC, Choose a lower freq transduce, Increase the scan line density, Change the gray scale map?

Back 84

Choose a lower freq transducer

Front 85

If you choose a lower freq transducer to image a highly attenuating liver, what tradeoff are you making?

Back 85

Decreased Spatial resolution

Front 86

What sound interaction would produce shadows posterior to a fetal head?

Back 86

Refraction

Front 87

Attenuation increases with increasing what?

Back 87

Path lenght, absorption, frequency, acoustic impedance

Front 88

What is the unit of impedance?

Back 88

Rayl

Front 89

What sound parameter is determined only by the medium?

Back 89

Propagation speed

Front 90

As you perform an abdominal ultrasound exam, you switch from a 3.5 to 7.0 MHz transducer to image a pancreatic mass. Compared to those of the previous transducer, what will the new attenuation rate and the wavelength be?

Back 90

Double attenuation rate, on-half wavelength