Test 3

Question 1

What is the pulse repetition period if the pulse repetition frequency is 5 kHz?

Answer 1

0.2 ms

Question 2

If the number of cycles in a pulse is increased, but the wavelength remains the same, what else is being increased or decreased?

Answer 2

The pulse duration is increased

Question 3

What is the term for the time from the beginning of one pulse to the beginning of the next pulse?

Answer 3

Pulse repetition period

Question 4

How does increasing the depth effect spatial pulse length?

Answer 4

The SPL has no change

Question 5

How does increasing the depth affect the duty factor?

Answer 5

The duty factor decreases

(Inversely related)

Question 6

How does increasing the depth effect pulse repetition period?

Answer 6

The PRP increases

(Directly related)

Question 7

How does increasing the depth affect the pulse duration?

Answer 7

The pulse duration has no change

Question 8

How does increasing the depth affect the propagation speed?

Answer 8

Depth and Propagation speed have NO RELATION.

Question 9

How does increasing the depth affect the number of cycles?

Answer 9

The depth and the number of cycles have NO RELATION.

Question 10

What is a change that would cause the pulse duration to increase?

Answer 10

Frequency decreases

Question 11

If the pulse repetition period (PRP) is 330 microseconds, what is the pulse repetition frequency?

Answer 11

3 kHz

Question 12

What is the fraction of time the sound is actually on?

Answer 12

Duty factor

Question 13

What is the duty factor?

Given: PD = 1
SPL = 0.5
PRF = 0.2

(Units not given to prevent overlap with another question. You should assume these are all matching units)

Answer 13

0.2 or 20%

Question 14

In diagnostic medical sonography, the beam would reach a reflector of approximately _____________ deep in 20 µs

Answer 14

3 cm

Question 15

In DMS, what is the most common unit for spatial pulse length?

Answer 15

mm

Question 16

What is the unit for Duty factor?

Answer 16

Unitless

Question 17

What is the SPL if the wavelength is 2mm and there are 3 cycles in the pulse?

Answer 17

6 mm

Question 18

PRF is the number of ____________ occurring in 1 second.

Answer 18

Pulses

Question 19

If the pulse repetition frequency decreases, what is something else that happen?

Answer 19

The duty factor decreases

Question 20

Use the information below and solve for PRP

Frequency - 6 MHz
Reflector Depth - 6 cm
Number of Cycles - 2

Answer 20

0.15633 ms or 156.33 microseconds

Question 21

Use the information below and solve for SPL

Frequency - 2 MHz
Reflector Depth - 6 cm
Number of cycles - 2

Answer 21

1.54 mm

Question 22

It took the beam 45.5 µs to reach the reflector. How deep did the beam travel?

Answer 22

7 cm

Question 23

You are scanning with a 4 MHz transducer that has 2 cycles per pulse. You note a mass that is at a distance of 8 cm. What is the pulse repetition frequency for this example?

Answer 23

9.57 kHz

Question 24

What is the relationship of frequency to absorption?

Answer 24

If frequency is doubled, absorption is doubled.

Question 25

True/False Continuous wave differs in that the probe has only one crystal to send and receive signals and pulse wave probes have two crystals.

Answer 25

False

Question 26

What determines the number of cycles in a pulse?

Answer 26

Backing layer

Question 27

True/False A longer spatial pulse length yields better image resolution

Answer 27

False

Question 28

What can the sonographer do to obtain the best image of a specular reflector?

Answer 28

The sonographer can maneuver their probe perpendicular to the interface

Question 29

What does a duty factor of 1 mean?

Answer 29

That the machine is always on.`

Question 30

You are scanning with a 3 MHz transducer that has 2 cycles per pulse. You note a mass that is at a distance of 11 cm. What is the pulse repetition frequency? **Round to two decimal places**

Answer 30

6.96 kHz

Question 31

The intensity of the beam is 20 mW/cm^2 and you reduce the intensity by one half, what is the decibel loss?

Answer 31

3 dB

Question 32

What happens to the intensity if the amplitude is increased by a factor of 3?

Answer 32

Amplitude is increased by a factor of 9

Question 33

The intensity of an ultrasound beam is 1000 mW/cm^2. You increase the power by 40 db. What is the new intensity of the beam?

Answer 33

10,000,000 mW/cm^2

Question 34

With absorption, acoustic energy is converted to:

Answer 34

Heat

Question 35

What is the best estimate of how much a 8 MHz beam will be reduced if it travels a total of 5 cm in soft tissue?

Answer 35

20 dB

Question 36

What is the expected attenuation of a 5MHz sound beam that has returned from a soft tissue target 6cm away?

Answer 36

30 dB

Question 37

What is something else that happens when stiffness is increased?

Answer 37

Propagation speed is increased (directly related)

Question 38

True/False Attenuation always results in a decibel loss

Answer 38

False

Question 39

How are frequency and attenuation related?

Answer 39

Directly related

Question 40

What is the attenuation coefficient for a 6MHz probe traveling 2cm?

Answer 40

3 dB/cm

Question 41

What is the half value layer for a 12 MHz transducer?

Answer 41

0.5 cm

Question 42

You had an initial intensity of 10,000 mW/cm^2. You are scanning with a 4 MHz transducer and the beam had a total path length of 10 cm. What is the final intensity?

Answer 42

100 mW/cm^2

Question 43

What term describes the distance between compression zones?

Answer 43

Wavelength

Question 44

What term describes the time between compression zones?

Answer 44

Period

Question 45

List all the components that go into beam attenuation:

Answer 45

Reflection Refraction Transmission Absorption

Question 46

It takes _________ microseconds for ultrasound to travel 1.54 cm in soft tissue.

Answer 46

10 microseconds

Question 47

Intensity is the _________ in a wave divided by ___________

Answer 47

Intensity = Power divided by Area

Question 48

Intensity is proportional to ___________ squared

Answer 48

Intensity is proportional to amplitude squared

Question 49

If power is doubled, and the area remains unchanged, intensity is ___________

Answer 49

Halved

Question 50

If amplitude is doubled, intensity is ___________

Answer 50

Quadrupled

Question 51

If a sound beam has a power of 10 m/W and a beam area of 2cm^2, the spatial pulse average intensity is ___________ mW/cm^2

Answer 51

5

Question 52

Attenuation is the reduction in _____________ and _____________ as a wave travels through a medium.

Answer 52

reduction in amplitude & intensity

Question 53

Attenuation consists of ___________, ___________, and _____________ .

Answer 53

Absorption, reflection, and scattering.

Question 54

The attenuation coefficient is attenuation per ____________ of sound traveled.

Answer 54

Centimeter

Question 55

For soft tissues, there is approximately ___________ dB of attenuation per centimeter for each megahertz of frequency.

Answer 55

0.5 dB

Question 56

For soft tissues, the attenuation coefficient at 3 MHz is approximately __________ .

Answer 56

1.5 dB/cm

Question 57

The attenuation coefficient in soft tissue ____________ while frequency increases.

Answer 57

Increases

Question 58

Absorption is the conversion of __________ to __________.

Answer 58

Sound to Heat.

Question 59

The imaging depth (penetration) _____________ while frequency increases.

Answer 59

decreases

Question 60

The depth at which half-intensity occurs in soft tissues at 7.5 MHz is _________ .

Answer 60

0.8 cm

Question 61

For an incident intensity of 2 mW/cm^2 and impedances of 49 and 51 rayls, the reflected intensity is _________ mW/cm^2 and the transmitted intensity is ______mW/cm^2

Answer 61

(0.0008 reflected & 1.9992 transmitted)