day 3

Question 1

separated in time with gaps of no ultrasound

Answer 1

pulses

Question 2

consists of pulses separated by
gaps in time

Answer 2

pulsed ultrasound

Question 3

number of cycles occurring per second for a continuous wave

Answer 3

frequency

Question 4

number of cycles per second that would occur if it were a continuous wave

Answer 4

pulsed wave

Question 5

number of pulses that occur in
1 second

Answer 5

pulse-repetition frequency

Question 6

PRF is commonly expressed in

Answer 6

kilohertz (kHz)

Question 7

refers to the time for one cycle
to occur

Answer 7

period

Question 8

refers to the time from the beginning of one pulse to the beginning of the next

Answer 8

pulse-repetition period (PRP)

Question 9

time that it takes for one pulse to occur

Answer 9

pulse duration

Question 10

Sonographic pulses are typically _ or _ cycles long

Answer 10

2 to 3

Question 11

Doppler pulses are typically _ to _ cycles long

Answer 11

5 to 30

Question 12

fraction of time that pulsed ultrasound is

Answer 12

duty factor

Question 13

PD increases, the DF ____

Answer 13

increases

Question 14

PRF increases, PRP ____ and duty factor ____

Answer 14

PRF increases, PRP decreases and duty factor increases

Question 15

length of a pulse from front to back, equal to the length of each cycle times the number of cycles in the pulse

Answer 15

Spatial Pulse Length

Question 16

length of each cycle

Answer 16

wavelength

Question 17

length of space occupied by a pulse

Answer 17

SPL

Question 18

If the number of cycles in a pulse increases, SPL ____

Answer 18

increases

Question 19

frequency increases, wavelength and SPL ____

Answer 19

decrease

Question 20

In contrast to continuous wave ultrasound, which can be described by a single frequency, ultrasound pulses contain a range of frequencies

Answer 20

bandwidth

Question 21

bandwidth divided by operating
frequency, unitless

Answer 21

fractional bandwidth

Question 22

reciprocal of fractional bandwidth (operating frequency divided by bandwidth) is called

Answer 22

quality factor

Question 23

range of frequencies contained in a pulse

Answer 23

bandwidth

Question 24

measure of how far a variable gets away from its normal, undisturbed value

Answer 24

amplitude

Question 25

maximum variation that occurs in an acoustic variable

Answer 25

atenuation

Question 26

ability to accomplish work

Answer 26

energy

Question 27

form of mechanical energy that can do work

Answer 27

sound

Question 28

rate at which energy is transferred from one part of a system to another or from one location to another

Answer 28

power

Question 29

rate at which energy passes through a unit area

Answer 29

intensity

Question 30

weakening of sound while it propagates, reduction in amplitude and intensity as sound travels is called

Answer 30

attenuation

Question 31

encompasses the absorption of sound while it travels and the reflection and scattering of the sound (echoes) while it encounters tissue interfaces and heterogeneous tissues

Answer 31

attenuation

Question 32

dominant factor that contributes to attenuation of ultrasound in soft tissues

Answer 32

absorption

Question 33

units used to quantify attenuation

Answer 33

decibels

Question 34

attenuation that occurs with each centimeter the sound wave travels

Answer 34

attenuation coefficient (ac)

Question 35

attenuation coefficient increases, attenuation ___

Answer 35

increases

Question 36

frequency increases, attenuation ___

Answer 36

increases

Question 37

frequency increases, penetration ____

Answer 37

decreases