Chap 4 Lvl 1

Question 1

What is a continuous wave

Answer 1

A continuously transmitted wave where the pulse is simultaneously transmitted and received

Question 2

Negatives of a continuous wave

Answer 2

• A lack of range specificity (range ambiguity)
• overlapping waves that make it impossible to determine the distance of the source you’re targeting

Question 3

Is it easier to distinguish space between structures that are farther apart or closer together?

Answer 3

It is easier to distinguish between structures that are farther apart

Question 4

Shorter vs longer pulse

Answer 4

A shorter pulse will give you a better axial resolution due to less attenuation

Question 5

Why do we use pw for ultrasound

Answer 5

Cw is unable to provide a range resolution to understand depth so we need to use a pulse wave to allow receiving waves to not overlap

Question 6

What is Pulse duration

Answer 6

The amount of time a transmitted pulse last.

Question 7

What is the pulse repetition period

Answer 7

Refers to the time a pulse starts and the following pulse begins

Question 8

What is the reciprocal to pulse repetition period

Answer 8

PRP=1/Pulse Repetion Frequency

Question 9

What is the Pulse Repetition Frequency

Answer 9

The number of pulses that occur per time

Question 10

What is the duty factor

Answer 10

The time the source is transmitting energy divided by the time until the process is repeated

Question 11

Equation for duty factor

Answer 11

DF=Pd/PRP x 100

Question 12

What is the duty factor for a continuous wave?

Answer 12

1, because a continuous wave is always transmitting and receiving

Question 13

If a Pulse duration is longer than ____ is greater

Answer 13

Duty factor

Question 14

What does the duty factor represent

Answer 14

The % of time the system is actively transmitting energy into the patient.

Question 15

What happens if the duty factor is too large

Answer 15

A greater build up of heat and in turn could cause a greater risk of bio effects

Question 16

What is range resolution

Answer 16

the ability of pulsed ultrasound to precisely locate a returning echo.

Question 17

Range resolution equation

Answer 17

Range resolution=spatial pulse length/2

Question 18

What are the pulse wave parameters

Answer 18

Define the duration of the pulse, how often the pulse is repeated, and the spatial length the pulse occupies in the medium

Question 19

How are the frequency and period determined in echo

Answer 19

Both are determined by the vibration of the crystal

Question 20

Equation for pulse duration

Answer 20

PD = period x # of cycles

Question 21

How to determine how often a transmit will be repeated

Answer 21

The time it will take for the sound wave to travel the required round trip distance

Question 22

What is the Spatial pulse length

Answer 22

The entire physical distance the pulse occupies in the medium

Question 23

Equation for spatial pulse length

Answer 23

SPL = wavelength x # of cycles

Question 24

How does spatial pulse length affect axial resolution

Answer 24

Fewer cycles and shorter wavelength will improve axial resolution. Vice versa for poor resolution

Question 25

In terms of pulse waves. What are factors of time

Answer 25

• pulse duration
• Pulse repetion period
• duty factor

Question 26

In terms of pulse waves, what are factors of distance

Answer 26

• spatial pulse length
• wavelength