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During performance of an obstetrical 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 the ultrasound system?

a.  Frequency 
b.  Propagation Speeded.
c.  Power
d.  Intensity
e.  Echo signal amplification
b. Propagation Speed is determined by the medium through which the sound passes. It is not user-controllable..
PRF and PRP are determined only by the imaging depth



a. true    b. False
TRUE
pulse repetition frequency is high when systems image only to a shallow depth
PRF is reduced when system change to greater depth
Two waves can have identical pulse repetition frequencies, even if their pulse repetition periods are different.



a. True     b. False
False.
Two wave can never have identical PRFs if their  pulse repetition period are different
pulse repetition period and pulse repetition frequency are inversely related
The most relevant intensity with respect to tissue heating is SPTA (spatial peak temporal average intensity)

a. True     b. False
a. True

Important in the study of bio-effect
The duty factor describes the relationship of the beam intensity with pulse repetition frequency



a. True     b. False
b. False



The duty factor describes the relationship of the beam intensity with pulse repetition frequency
Increasing the frequency on a multi-frequency transducer from 3.5 MHz to 5.0 MHz will



a.  Increase the sound propagation        speed

b.  Increases the pulse length

c.   Increasing penetration

d.  Decreasing the pulse repetition          frequency

e. Decrease the wavelength
e. Decrease the Wavelength
As frequency increases, wavelength decreases. The wavelength is determined by the frequency and the speed of sound in the medium. The relationship between frequency, wavelength and propagation speed is described by the equation:  l= C/f, in which l represents wavelength, c represents propagating speed, and f represents frequency
Which of the following describes sound propagation speed through a vacuum?



a.  sound travels as transverse wave      through a vacuum.

b.  when sound travels through a          vacuum, the propagation speed        increases to 3, 300,000 m/s

c.  sound travels at the speed of            light when coursing through a          vacuum

d.  sound propagation is random in a      vacuum

e.  sound cannot travel through a          vacuum
e. Sound cannot travel through             vacuum.
Sound requires a material medium for propagation. The physical movement of particles within a medium transports the sound. Since there are no particles to vibrate in a vacuum, sound cannot propagate.
When your patient asks you how much longer the ultrasound test will take, his/her voice is in the audible frequency range. Which of the following frequencies is in the audible frequency range?



a.  100 MHz
b.  10 KHz
c.  10 Hz
d.  10,000 MHz
e.  1,000,000 Hz
b. 10 KHz
The audible frequency range of sound is from approximately 20 Hz to 20 000 Hz or 20kHz
Which most correctly describes sound propagation in a medium



a.  in sound propagation, a molecule      travels from one end of the              medium to another
b.  a molecules oscillates back and          forth to propagate sound waves        but does not move from one end      of the medium to another
c.  a molecules does not vary its           position as a sound wave travels d.  each molecule expands and              contracts to propagate a sound        wave through a medium
e.  sound waves cannot travel                through a medium
b. a molecules oscillates back and         forth to propagate sound waves       but does not move from one end     of the media to another
Sound cannot travel through vacuum; it must travel through a medium, where molecules are alternately compressed and rarefied.
The maximum cyclical change in a quantity is known as



a.  Amplitude
b.  Pressure
c.  Power
d.  Intensity
e.  Decibel
a. Amplitude
Amplitude is the bigness of a wave. it is the difference between the maximum value and the average or undisturbed value of an acoustic variable.  also known as the difference between the minimum and the average value of the acoustic variable.
What characteristic of a medium determined the speed of sound in a medium?

a.  propagation speed
b.  elasticity
c.  wavelength
d.  volume
e.  stiffness
e. Stiffness
Stiffness and speed are directly related. As material becomes stiffer, the speed of sound in the material increases. In two otherwise identical media, the speed of sound will be higher in the stiffer medium.
Which of the following terms denotes the time it takes for one cycle to occur?

a.  frequency
b.  amplitude
c.  wavelength
d.  period
e.  pressure
d. Period
Period is the time it takes a wave to vibrate a single cycle. or the time from the start of a cycle to the start of the next cycle.
If the number of cycles in a pulse is increased but the wavelength remains the same, which of the following is true?



a.  The frequency is increased

b.  The propagation speed is                   increased

c.  the pulse duration is increased

d.  the period is decreased

e.  the stiffness is decreased
c. the pulse duration is increased
The pulse duration is the time it takes to complete one pulse. If the number of cycles in the pulse increased, it will take more time for one pulse to occur.
The region of low pressure and density that are formed during sound propagation are termed?



a.  compressions

b.  shear waves

c.  rarefactions

d.  cavitations

e.  stiffness
c. rarefactions
sound cannot travel through a vacuum; it must travel through a medium, where molecules are alternately compressed and rarefied.
The sound propagation speed used to calibrate range-measuring circuits on diagnostic ultrasound instruments is:



a.  1.54m/s

b.  1560 mm/s

c.  1,46 mm/µs

d.  1540 m/s

e.  146 000 cm/s
d. 1540 m/s
the speed of sound in soft tissue is 1540 m/s, 1.54mm/µs or 1.54 km/s this value approximately 1 mile per second
Which of the following properties would result in increased propagation speed of a medium?



a.  Increased stiffness

b.  Increased density

c.  increased frequency

d.  increased distance

e.  increased amplitude
a. increased stiffness.
propagation speed decreases with increased density. frequency does not affect propagation speed. increasing distance will increase the round-trip travel time but will not affect the rate of travel (propagation speed). increasing amplitude will increase the sound intensity but have not affect on propagation speed.
Which of the following frequencies is considered to be ultrasound?



a.  2 000 Hz

b.  20 Hz

c.  2 MHz

d.  200 Hz

e.  2 Hz
c. 2 MHz
ultrasound frequency is greater than 20 kHz
Which statement about the two pulse trains displayed below is true?
Pic a. 
Pic b. 
a.  pic a has a higher frequency than      pic b
b. pic b has a shorter period than pic     a
c. pic a has a shorter wavelength         than pic b
d. pic a has a better axial resolution       than pic b
e. pic b has a greater spatial pulse         length than pic a
b. Pic B has shorter period than pic A
Period is the time it takes one completed cycle to occur. the pulse train with the shorter wavelength would be the higher frequency. that would be B. The shorter pulse (B) will have the better axial resolution. the longest pulse (A) has the greatest spatial pulse length.
The speed of sound is defined as the




a. speed of the vibrating particles in       the medium
b.  speed at which the sound wave        propagates through the medium
c.   number of cycles per second of        the vibrating particle

d.  inverse of the frequency

e.  speed of the electrical impulse            applied to the piezoelectric                element
b. speed at which the sound wave propagates through a medium
A longitudinal wave is characterized by



a.  a wave that demonstrates only          sagittal imaging planes

b.  randomized particle motion

c.  a constant acoustic velocity of         1540 m/s

d.  particle motion occurring in the          same direction as propagation

e.  particle motion occurring                  perpendicular to the direction of        propagation
d. particle motion occurring in the same direction as propagation
in a longitudinal wave, particle move in the same direction that the wave propagates. sound is a longitudinal wave.
The following adjustment would decrease beam intensity:



a.  increasing acoustic output

b.  decreasing receiver gain

c.  increasing focusing

d.  increasing beam area

e. increasing amplitude
d. increasing beam area
if the same acoustic energy is applied over a large area, the overall intensity would be reduced. Increasing acoustic output would have the opposite result: it would increase beam intensity. Receiver gain amplify the reflected signal. it does not affect the beam intensity. increasing the amount of focusing and increasing amplitude would both result in increased beam intensity
Which of the following describes an ultrasound wave in human  tissue?



a.  mechanical longitudinal wave

b.  radioactive wave

c.  transverse rarefactions wave

d.  electromagnetic wave

e.  electronic piezoelectric wave
a. mechanical longitudinal wave
What is the velocity of an ultrasound wave in bone?



a.  333 m/s

b.  8050 m/s

c.  1540 m/s

d.  4080 m/s

e.  3 500  m/s
e. 3 500 m/s Bone
soft tissue speed is 1,540 m/s
liver 1560 m/s
blood 1560 m/s
muscle 1600 m/s
frequency of the ultrasound wave is defined as:



a.  speed of the vibrating particle in        medium

b.  speed at which the sound wave        propagates through the medium

c.  number of cycles per second

d.  inverse of the wavelength

e.  number of electrical impulses           applied to the transducer per           second
c. number of cycles per second.
When you switch from a 2.5 MHz to a 5 MHz transducer, the sound wavelength



a.  doubles

b.  quadruple

c.  halves

d.  quarters

e.  is unaffected
c. halves
wavelength and frequency are inversely  related. as frequency increase, wavelength decreases.
wavelength (mm) = 1.54 mm/µs / frequency (MHz)
The period of 5 MHz frequency is?



a.  .02 s

b.  .002 s

c.  .0000 2 s

d.  .000002 s

e.  .0000002 s
e.000002 s
period and frequency are inversely related to each other.
as frequency increases period decreases
as frequency decreases period increases
if one parameter remain constant then the other remains unchanged
P = 1/f
What do waves transfer from one location to another?



a.  matter

b.  molecules

c.  energy

d.  water
c. waves carry energy from place to place
Which of the following terms does not belong with the others?



a.  compression

b.  region of high density

c.  regions of high pressure

d.  wide molecular spacing
d.  wide molecular spacing
All of the following are acoustic parameters except:



a.  pressure

b.  period

c.  propagation speed

d.  frequency
a. pressure
Acoustic Parameters: period, frequency, amplitude, power, intensity, wavelength and propagation speed
Pressure is an acoustic variable
Which of the following waves is infrasonic?



a.  4 MHz

b.  400 KHz

c.  28 Hz

d.  2 Hz
d. 2 Hz
a wave with a frequency less than 2 Hz cannot be heard because it is frequency less than the lowered limit of sound hearing
If all other factors remain unchanged, what happens to the duty factor when the pulse repetition frequency increases?



a.  increases

b.  decreases

c.  remains the same
a. increases
the duty factor is the percentage of time that the system is transmitted. if pulse duration increases the duty factor increases.
The intensities in order of decreasing values are:



a.  SPTA,SATA,SPPA, SPTP

b.  SPTA,SPTP, and SPPA

c.  SATA,SPTP and SPPA

d.  SPTP, SPPA, SPTA, and  SATA
d. SPTP, SPPA, SPTA and SATA
The sonographer adjusts the depth of view of an ultrasound scan from 8 cm to 16 cm.  Would each of the following parameters:



a.  increase

b.  decrease

c.  remains the same
c. remains the same
x of y cards