DMS 206 FINAL EXAM

Jackson College

What is the range of periods commonly found in diagnostic ultrasound systems?

10 to 100 ns

0.2 to 1 ms

0.001 to 1 s 

0.5us to 0.1 us

 0.5us to 0.1 us

If the wavelength of a sound wave is doubled and the frequency is held constant the period of that sound wave may:

double also

is halved

remains the same

is quartered

is 4 times greater

remains the same

If a clinician changes the transmit power, from 100 mW to 1 mW, by how much has the transmit power changed?

+ 20 dB

-20 dB

+10 dB

-10 dB

-100 dB

-20 dB

As the bulk modulus of a medium decreases as the propagation speed _____.

increases

decreases

remains the same

doubles

decreases

Which of the following units are appropriate to describe the period of an acoustic wave?

mm/us

meters

microseconds

cm^3

microseconds

Two waves arrive at the same location and interfere. The resultant sound wave is smaller than either of the two original waves. What is this called?

 

Amplification

Spatial pulse length

Constructive interference

Deconstructive interference

deconstructive

As the density of a medium increases the propagation speed _______.

 increases

decreases

remains the same

depends on the sound source

increases

Which of the following is true of all waves?

A. they travel through a medium

B. all carry energy from one site to another

C. their amplitudes do no change

D. they travel in a straight line

B. all carry energy from one site to another

A decibel (dB) describes: 

amount of scattering

velocity of the sound wave

sum of two sound intensities

ratio of two sound intensities

ratio of two sound intensities

You are imaging a kidney with a 3.5 megahertz transducer. you changed to a 5.0 megahertz transducer. what will happen to the wavelength?

The wavelength will decrease 

The wavelength will remain the same.

The wavelength will increase.

Wavelength does not affected by a change in frequency.

The wavelength will decrease 

If the wavelength of a sound wave is doubled and the frequency is held constant, the period of that sound wave may:

 

Double

Remain the same

Is halved

Is quartered

Is 4 times greater

remain the same

With standard ultrasound imaging, what happens to the period of the wave as it propagates?

increases

decreases

remains the same

remains the same

What established the frequency of a diagnostic ultrasound?

 medium

transducer

choice 1 & 2

none of the above

transducer

Sound can be characterized as:

energy flowing through a vacuum

a variable

cyclical oscillations in certain variables

a principle of acoustics

cyclical oscillations in certain variables

Propagation speed is directly proportional to compressibility.

 

True or

False

False

An acoustic wave is traveling from medium X to medium Z. Medium X has a propagation speed of 1,457 m/sec and an impedance of 1.44 MRayls. Medium Z's propagation speed is 1,644 m/s and its impedance is 1.26 MRayls. The angle of incidence is 32 degrees. What is true of the angle of reflection?

A. it is greater than 32 degrees

B. it is equal to 32 degrees

C. it is less than 32 degrees

D. cannot be determined

B. it is equal to 32 degrees

In diagnostic imaging, what determines the spatial pulse length?

A. the ultrasound system

B. medium through the pulse travels

C. both A and B

D. neither A nor B

both A and B

A natural property of soundwaves to spread out the further they travel from the source is known as:

constructive interference

destructive interference

diffraction

refraction

diffraction

Damping material is a material that is added to the transducer assembly to limit the ringing of the transducer crystal after a pulse is generated. All of the following are effects of the added damping material EXCEPT

 

Spatial pulse length is shortened

Bandwidth is increased

Decreases the quality factor

Slightly degrades image quality and axial resolution

Slightly degrades image quality and axial resolution

The pulse repetition frequency is the ________.

A. product of the wavelength and propagation speed

B. reciprocal of period

C. sum of the pulse duration and listening time

D. reciprocal of pulse repetition period

reciprocal of pulse repetition period

If frequency increases what happens to the PD?

 increases

decreases

remains the same

decreases

The spatial pulse length describes certain characteristics of an ultrasound pulse. What are the units?

True

False

True

The product of the period and the number of cycles in the pulse is the:

 

pulse repetition frequency

continuous wave

pulse repetition period

pulse duration

pulse duration

If PD increases what happens to the DF?

increases

decreases

remains the same

increases

If depth is doubled what happens to the PRF?

 doubles

quadruples

halves

quartered

halves

An 8 MHz sound beam travels in soft tissue through a path length of 5 cm. What is the value of the attenuation?

A. 8 dB

B. 20 dB

C. 4 dB

D. 40 dB

20 dB

Which of the following terms doesn't belong with the others?

A. increased depth of view

B. decreased duty factor

C. increased PRP

D. decreased SPL

D. decreased SPL

What determines the pulse duration?

A. the source of the wave

B. the medium through which the pulse travels

C. Both A and B

D. neither A nor B

A. the source of the wave

A sonographer adjusts the output power of the wave emitted by the transducer. Which of the following also changes?

A. PRP

B. PRF

C. propagation speed

D. intensity

D. intensity

the impedance on one side of the interface is 2 times the impedance on the other, the intensity reflection coefficient is:

0.1

1 

0.33

0.033

0.1

Two pulses are produced by different transducers. The pulses are made up of the same number of cycles. The pulse containing the lower frequency has a ____________________.

Lower PRF

Shorter PD

Longer PD

Longer PRP

Longer PD

 An ultrasound pulse is passing through two media, medium A, soft tissue, has a propagation speed of 1540 m/s. Medium B, fat, has a propagation speed of 1450 m/s. If the density is the same for both media, which medium has the highest acoustic impedance?

 

Medium A has the highest acoustic impedance.

Medium B has the highest acoustic impedance

The acoustic impedance is the same for both media

Propagation speed has no effect on acoustic impedance.

Medium A has the highest acoustic impedance.

What is the dispersion of a sound wave uniformly in many different directions after striking a very small particle?

microscattering

backscattering

specular reflection

Rayleigh scattering

Rayleigh scattering

2 pulses are created by different transducers. Both have the same number of cycles. The pulse containing cycles of a lower frequency has a _______.

A. lower pulse repetition frequency

B. shorter pulse duration

C. longer pulse duration

D. longer pulse repetition period

C. longer pulse duration

True or False? In comparison to other locations along the length of an ultrasound beam, focusing is generally ineffective in the far zone.

True

False

True

All of the following are related to a dedicated CW Doppler transducer except:

A. wide bandwidth

B. high quality factor

C. higher sensitivity

D. range ambiguity

A wide bandwidth

A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. Is the following true or false? The near zone is the only region where the diameter of the sound beam decreases as depth increases.

True

False

True

For a disc-shaped PZT crystal producing continuous sound, which design will create a beam with the deepest focus?

A. large diameter, low frequency

B. large diameter, high frequency

C. small diameter, low frequency

D. small diameter, high frequency

B. large diameter, high frequency

Damping material is a material that is added to the transducer assembly to limit the ringing of the transducer crystal after a pulse is generated. All of the following are effects of the added damping material EXCEPT

Spatial pulse length is shortened

Bandwidth is increased

Decreases the quality factor

Slightly degrades image quality and axial resolution

Slightly degrades image quality and axial resolution

A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. Is the following true or false? If the narrowest diameter of a sound beam is at a depth of 8 cm, then the PZT crystal's diameter is 16 mm.

True

False

True

A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. Is the following true or false? The near zone is the only region where the diameter of the sound beam is smaller than the transducer's.

True

False

True

A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. Is the following true or false? If the diameter of the acoustic beam produced by a crystal is 8 mm at a depth of twice the near zone length, then the PZT crystal has a diameter of 8 mm.

True

False

True

Far field divergence ____________ with increasing Q value.

increases

decreases

has no effect

decreases

What is the region from the transducer to the smallest cross-sectional area of a sound beam called?

A. focus

B. half-value thickness

C. near zone

D. Fraunhofer zone

C near zone

The area that starts at the beam's smallest diameter and extends deeper is:

A. the distant zone

B. the Fresnel zone

C. the Fraunhofer zone

D. the depth of penetration

C. the Fraunhofer zone

With regard to the backing material of a pulsed ultrasound transducer, is the following true or false? The backing material decreases the quality factor.

True

False

True

True or False? The acoustic impedance of the skin is greater than the acoustic impedances of both the matching layer and the piezoelectric element.

True

False

True

True or False? The purpose of the backing material of an ultrasound transducer is to shorten the pulses, thereby creating images with better image quality.

True

False

True

What helps to determine the frequency of the sound produced by the transducer of a CW system?

A. piezoelectric crystal diameter

B. piezoelectric crystal thickness

C. damping material density

D. ultrasound system electronics

D. ultrasound system electronics

All of the following are true of the focus except:

A. it is at the end of the near zone

B. it is at the beginning of the Fraunhofer zone

C. it has the highest spatial peak intensity

D. it is at the start of the Fresnel zone

D. it is at the start of the Fresnel zon

A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. Is the following true or false? The far zone is the only region where the beam diameter exceeds the transducer diameter.

True

False

True

Which transducer element/crystal thickness would produce the highest frequency?

Thick element/crystal

Thin element/crystal

They will both produce identical frequencies

Crystal thickness has no effect on the frequency

Thin element/crystal

An ultrasound pulse is traveling in soft tissue. Which of the following is most important in the determination of the frequency of sound?

A. the propagation speed of the ultrasound transducer's matching layer

B. the thickness of the transducer's backing material

C. the impedance of the transducer's matching layer

D. the propagation speed of the transducer's active element

D. the propagation speed of the transducer's active element

All of the following occur with focusing except:

A. lower intensity at the focus

B. shorter near zone

C. more compact focal zone

D. smaller diameter beam diameter at the end of the near zone

A. lower intensity at the focus

These transducers focus the ultrasound beam electronically.

A. linear switched array

B. linear phased array

C. mechanical

D. annular phased array

E. convex or curvilinear array

E. convex or curvilinear array

All of the following terms describe the shape of a sound wave created by a tiny fragment of PZT except:

A. spherical

B. Huygen's wavelet

C. V-shaped

D. hourglass

D hourglass

How does a CRT steer the charged particles emitted by the electron gun, located in the back of the tube, so that they sweep across the front screen?

A. by phasing the source

B. by mechanically steering the gun

C. by sending them through a time-varying magnetic field

D. by reflecting the particles off of a mirrored surface

C. by sending them through a time-varying magnetic field

While using a linear sequential array transducer during a color Doppler exam, the shape of the grayscale image is most often _____, whereas the shape of the color Doppler portion of the imge is _____. A. rectangular, parallelogram

B. rectangular, sector

C. sector, trapezoid

D. square, rectangular

A. rectangular, parallelogram

Which of the following terms are associated with phased array transducers?

A. lens

B. multi-focus

C. mirror

D. adjustable

E. external

B. multi-focus

and

D. adjustable

Which best describes the elements in a linear sequential array transducer?

A. rectangular, 1/4 wavelength thick

B. rectangular, 1/2 to 1/4 wavelength wide

C. rectangular, 1 wavelength wide

D. squares, 1/2 wavelength thick

C. rectangular, 1 wavelength wide

True or False? Annular phased array transducers focus sound beams in all planes and at all depths.

 True

False

True

True or False? The "curved pattern" of delays in the electrical spikes used in a linear phased array transducer focuses the beam during reception.

True 

False

True

Ultrasound systems using these transducers do not actually steer the ultrasound beams to create a 2-D image.

A. linear switched(linear sequential) array

B. linear phased array

C. mechanical

D. annular array

E. convex or curvilinear array

F. vector array

G. A and E

G. A and E

How are the piezoelectric crystals excited when sing an ultrasound system with a sequential linear array transducer?

A. singly and in order: the first crystal, the second crystal, etc

B. in pairs: the first 2 crystals, the 3rd and 4th, etc

C. in a specific order

D. in a random sequence

C. in a specific order

What is the shape of the elements in an aannular phased array transducer?

A. rectangles

B. squares

C. wedges

D. circles

D. circles

True or False? All phased array transducer systems direct ultrasound pulses in many directions to create a 2-D image.

True

False

True

Which of the following techniques is internal focusing?

A. lens

B. curved crystal

C. electronic

B. curved crystal

_____________ describe how arrays are operated.

 

Linear

Phased

Sector

Convex

Phased

An advantage of a curvilinear transducer over a phased array sector transducer is the curvilinear's:

Low cost

Smaller footprint

Larger far field viewing area

Larger near field viewing area

None of the above

Larger near field viewing area

How are the piezoelectric crystals of a linear phased array transducer fired?

A. in a single specific pattern

B. in order, from top to bottom

C. at exactly the same time

D. at almost exactly the same time

D. at almost exactly the same time

Which transducer system is most likely to have the longest delay in its TGC curve?

A. 5 MHz linear array

B. 2.5 MHz annular array

C. 7.5 MHz mechanical

D. 5 MHz annular array

B. 2.5 MHz annular array

True or False? Both linear and phased array technologies have the ability to variably focus an ultrasound beam to different depth.

True

False

True

Huygens' Principle is based on ____.

A. refraction

B. constructive interference

C. transverse waves

D. interference

D. interference

Which of the following forms of focusing is different from the others? A. lens

B. mirror

C. phased

D. dynamic receive

D. dynamic receive