DMU 3313 Kremkau

A wave is a traveling variation in quantities called wave _____

variables

Sound is a traveling variation in quantities called _____ quantities

acoustic

Ultrasound is sound with a frequency greater than _______ Hz

20,000

acoustic variables include _______,__ _______ and particle motion

pressure, density

Which of the following are in ultrasound range?

a. 15 Hz

b.15,000 Hz

c. 15 Hz

d. 30,000 Hz

e. 0.004 MHz

30,000 Hz

which of the following is not an acoustic variable?

a. pressure

b. propagation speed

c. density

d. particle motion

propagation speed

frequency is the number of _____ an acoustic variable goes through in a second.

cycles

the unit of frequency is _____,__ which is abbreviated as ____.

Hertz, Hz

period is the _______ that it takes for one cycle to occur

time

period decreases while ______ increases.

frequency

wavelength is the length of _____ over which one cycle occurs

space

propagation speed is the speed with which a(n) ______ moves through a medium

wave

wavelength is equal to ______. ___ divided by _______

propagation speed, frequency

the ______ and ________ of a medium determine propagation speed

density, stiffness

Propagation speed increases if ______ is increased

stiffness

the average propagation speed in soft tissues is ___ m/s or ______ mm/µs

1540, 1.54

propagation speed is determined by the _______

medium

What is the correct classification of matter in order of increasing sound propagation speed?

gas, liquid, solid

waves can carry _____ from one place to another.

information

From given values for propagation speed and frequency, _________ can be calculated

wavelength

propagation speed in bone is ____________ that in soft tissues

higher than

sound travels fastest in __________

steel

Solids have higher propagation speeds than liquids because they have greater ____________

stiffness

sound travels most slowly in _________.

gases

sound is a ____________ wave

mechanical longitudinal

if two media have different stiffness, the one with the higher stiffness will have the higher propagation speed. True or False?

true

The wavelength of 7 MHz ultrasound in soft tissues is ______ mm.

.22

wavelength in soft tissues ______ while frequency increases

decreases

it takes ______ for ultrasound to travel 1.54 cm in soft tissue

10

if propagation speed is doubled and frequency is held constant, the wavelength is _________

doubled

if frequency in soft tissue is doubled, propagation speed is ______.

unchanged

if wavelength is 2mm and frequency is doubled, the wavelength becomes ________ mm

1

the second harmonic of 3 MHz is _______ MHz

6

Nonlinear propagation means that ________________.

the waveform changes shape while it travels

if the density of a medium is 1000kg.m3 and the propagation speed is 1540 m/s, the impedance is ________

1,540,000

if two media have the same propagation speed but different densities m the one with the higher density will have the higher impedance. True or False?

true

if two media have the same density but different propagation speeds, the one with the higher propagation speed will have the higher impedance. True or false?

true

impedance is _____ multiplied by _______________

density, propagation speed

the abbreviation for CW stands for _____

continuous wave

PRF is the number of _____ occurring in 1 second

pulses

pulse repetition _____ is the time from the beginning of one pulse to the beginning of the next

period

the PRP ______ while PRF increases

decreases

PD is the ______ it takes for a pulse to occur

time

SPL is the __________ of ____________ that a pulse occupies while it travels

length, space

_________ is the fraction of time that pulsed ultrasound is actually on

Duty factor

PD equals the number of cycles in the pulse multiplied by _________

period

SPL equals the number of cycles in the pulse multiplied by _______

wavelength

the DF of continuous wave sound is

1

if the wavelength is 2mm, the SPL for a three-cycle pulse is ______mm

6

The SPL in soft tissue for a two-cycle pulse of frequency 5MHz is _____mm

0\.6

The PD in soft tissue for a two cycle pulse of frequency 5MHz is _____µs

0\.4

For a 1kHz PRF, the PRP is _______ms

1

if the PD in soft tissue for a two cycle pulse of frequency 5MHz is 6 µs, and For a 1kHz PRF, the PRP is 1ms, the DF is ___

6

how many cycles are there in 1 second of continuous wave 5MHz ultrasound?

5,000,000

How many cycles are there in 1 second of pulsed 5MHz ultrasound with a DF of 0.01?

50,000

If the 50,000 cycles are pulsed in 1 second of pulsed 5 MHz ultrasound with a DF of 0.01, how many cycles did pulsing eliminate?

99%

for pulsed ultrasound, the DF is always ________ 1

less than

_________ is a typical DF for sonography

0\.1

amplitude is the maximum _________ that occurvs in an acoustic variable

variation

intensity is the _________ in a wave divided by ___________

power, area

A unit for intensity is _________.

mW/cm2

intensity is proportional to ________ squared

amplitude

If power is doubled and area remains unchanged, intensity is _________

doubled

if area is doubled and power remains unchanged, intensity is ________

halved

If both power and area are doubled, intensity remains ________

unchanged

if amplitude is doubled, intensity is _______

quadrupled

If a sound beam has a power of 10 mW and a beam area of 2 cm2, the spatial average intensity is ______mW/cm2

5

attenuation is the reduction in _______ and __________ as a wave travels through a medium

amplitude, intensity

Attenuation consists of ________,,__ ____ __,,__ and _________

absorption, reflection, scattering

the attenuation coefficient is attenuation per ________ of sound travel

centimeter

attenuation and attenuation coefficient are given in units of _________ and __________

dB, dB/cm

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

1\.5 dB/cm

The attenuation coefficient in soft tissue _________ while frequency increases

increases

For soft tissue, if frequency is doubled, attenuation is ____________.__ If path length is doubled, attenuation is _______________.__ If both frequency and path length are doubled, attenuation is ______________.

doubled, doubled, quadrupled

If frequency is doubled and path length is halved, attenuation is _____________.

unchanged

Absorption is the conversion of __________ to ____________

sound, heat

Absorption can be greater than attenuation in a given medium at a given frequency. True or False?

false

Attenuation is higher in bone than in soft tissue. True or false?

true

when ultrasound encounters a boundary with perpendicular incidence, the ________ of the tissues must be different to produce a reflection

impedances

With perpendicular incidence, two media _______ and the incident _____________ must be known to calculate the reflected intensity

impedances, intensity

WIth perpendicular incidence, two media _____________ must be known to calculate the intensity reflection coefficient

impedances

for an incident intensity of 2 mW/cm2 and impedances of 49 and 51 rayls, the reflected intensity is mW/cm2, and the transmitted intensity is _________ mW/cm2

0\.0008, 1.9992

if the impedances of the media are equal, there is no reflection. True of false?

true

With perpendicular incidence, the reflected intensity depends on the _________

impedance difference and the impedance sum

Reflection of sound in many directions while it encounters rough media junctions or particle suspensions is called

scattering

backscatter helps make echo reception less dependent on incident angle. True or false?

true

What must be known to calculate the distance to a reflector?

travel time and speed

No reflection will occur with perpendicular incidence if the media ___________ are equal

impedances

Scattering occurs at smooth boundaries and within homogeneous media. true or false?

false

What are the parts of the circulatory system?

heart, artery, arteriole, capillary, venule, vein

the _______ are the tiniest vessels in the circulatory system

capillaries

in which of the following can Doppler ultrasound detect flow?

the heart, arteries, veins

to flow is to move in a ________

stream

the characteristic of a fluid that offers resistance to flow is called ________________

viscosity

poise is a unit of _________

viscosity

pressure is ________ per unit area

force

pressure is _____________

omnidirectional

flow is a response to pressure __________ or____________

difference, gradient

if the pressure is greater at one end of a liquid-filled tube or vessel than it is at the other the liquid will flow from the _______ -pressure end to the _________ pressure end

higher, lower

The volumetric flow rate in a tube is determined by _________ difference and ____________

pressure, resistance