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vocabulary Flashcards

1
Q

the effects of the medium upon the sound wave

A

acoustic propagation properties

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2
Q

the effects of the sound wave upon the biologic tissue through which it passes

A

biologic effects

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3
Q

concentration of the force in an area, Units= pascals (Pa)

A

pressure

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4
Q

concentration of mass in a volume, UNITS= Kg/cm^3

A

density

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5
Q

measure of particle in motion, UNITS=cm, feet, mile

A

distance

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6
Q

the time it takes a wave to vibrate a single cycle, or the time from the start of one cycle to the start of the next cycle,
determined by the sound source
not adjustable
UNITS= time

A

Period

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7
Q

number of particular events that occur in a specific duration of time
Determined by the sound source
not adjustable
UNITS=per second, hertz, Hz, 1/second

A

frequency

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8
Q

the bigness of a wave. The difference between the maximum value and the average or undisturbed value of an acoustic variable. Also the difference between the minimum value and the average of the acoustic variable
Determined by the sound source (but is affected by the medium)
adjustable
UNITS= any of the acoustic variable
-pressure-pascals
-density-g/cm^3
-distance

A

amplitude

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9
Q

rate of energy transfer or the rate at which work is performed
Determined by the sound source
adjustable
UNITS=watts

A

power

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10
Q

the concentration of energy in a sound beam. (how power of the wave or beam is distributed in space)
Determined by the sound source
Adjustable
W/cm^2

A

intensity

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11
Q

distance or length of one complete cycle
Determined by both the sound source and the medium
Not adjustable
UNITS=mm, meters, cm

A

wavelength

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12
Q

rate at which a sound wave travels through a medium
Determined by the medium
Not adjustable
UNITS=meters per second, mm/us, or any distance divided by time

A

Propagation speed

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13
Q

the ability of an object to resist compression

A

stiffness

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14
Q

describes the relative weight of a material

A

Density

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15
Q

the actual time from the start of a pulse to the end of that pulse, (a single transmit “on” time)
Determined by sound source
not adjustable
UNITS=time

A

pulse duration

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16
Q

Distance that a pulse occupies in space from the start to the end of a pulse
Determined by both the sound source and the medium
not adjustable
UNITS=distance

A

spatial pulse length

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17
Q

the time from the start of one pulse to the start of the next pulse,(one duration plus one listening time)
Determined by the sound source and imaging depth
adjustable
UNITS= time

A

Pulse repetition period

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18
Q

the number of pulses that an ultrasound system transmits into the body each second
Determined by the sound source and max. imaging depth
adjustable
UNITS= Hz

A

Pulse repetition frequency

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19
Q

the percentage or fraction of time that the system transmits a pulse
Determined by the sound source
adjustable
Unitless
For continuous wave it is 1.0 or 100% because it is always transmitting

A

Duty factor

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20
Q

refers to distance or space,

A

spatial

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21
Q

refers to all time, transmit (pulse duration) and receive

A

Temporal

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22
Q

refers only to the transmit time (pulse duration). average intensity for the pulse duration only (ignore listening time)

A

Pulsed

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23
Q

the number of decibels of attenuation that occurs when sound travels one centimeter
UNITS= dB/cm

A

attenuation coefficient

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24
Q

The distance sound travels in a tissue that reduces the intensity of sound to one half its original value
Also known as Penetration depth, depth of penetration, half boundary layer
Units= any unit of length

A

Half-value layer thickness

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25
Q

the acoustic resistance to sound traveling in a medium.
calculated by multiplying the density by the speed of the medium
Determined by the medium
UNITS=rayls, Z

A

impedance (characteristic impedance)

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26
Q

Incident sound beam strikes the boundary at exactly 90 degrees

A 
Normal incidence
(perpendicular,
orthogonal,
right angle,
90 degrees)
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27
Q

occurs when the incident sound beam strikes the boundary at any angle other than 90 degrees

A

Oblique incidence

non-perpendicular

28
Q

describes the property of certain materials to create the voltage when they are mechanically deformed or when pressure is applied to them,

A

Piezoelectric effect

29
Q

piezoelectric materials change shape when a voltage is applied to them through a process called

A

reverse piezoelectric effect

30
Q

materials which convert sound into electricity (and vice versa)

A

Piezoelectric materials

ceramic, active element, crystal

31
Q

the cylindrical tube, constructed of metal or plastic, that protects the internal components of the transducer from damage. Also insulated the patient from electrical shock

A

case

32
Q

a thin metallic barrier lining the inside of the case.

  • Prevents spurious (not intended) electrical signals in the air, unrelated to diagnostic information from entering the transducer.
  • Prevents electrical noise from contaminating the clinically important electrical signal used to create diagnostic images
A

electrical shield

33
Q

the piezoelectric crystal itself

  • in simple probe it is shaped like a coin
  • related to the characteristics of the sound beam
  • 1/2 wave length thick
A

PZT or active element

34
Q

a thin barrier of cork or rubber that isolates or “uncouples” the internal components of the transducer form the case
-prevents vibrations in the case from inducing an electrical voltage in the PZT of the transducer

A

acoustic insulator

35
Q

Provides an electrical connestion between the PZT and the ultrasound system

A

Wire (channel)

36
Q

Positioned in front of the PZT at the face of the transducer

  • increases the efficiency of sound energy transfer between the active element and the body
  • protects the active element
  • 1/4 wavelength thick
A

matching layer

37
Q

Bonded to the back of the active element, it reduces ringing of the PZT

  • made of epoxy resin
  • enhances AXIAL RESOLUTION
A

backing material (damping element)

38
Q

1/2 wavelength thick

A

active element

39
Q

1/4 wavelength thick

A

matching layer

40
Q

describes one measure of the detail found in an image

  • measures the ability of a system to display two structures that are very close together when the structures are PARALLEL TO THE SOUND BEAM’S MAIN AXIS
  • determined by spatial pulse length
  • not adjustable
A 
Axial resolution
Longitudinal,
Range,
Radial,
Depth
41
Q

the ability to distinctly identify two structures that are very close together when they are side by side or PERPENDICULAR TO THE SOUND BEAM’S MAIN AXIS
-Determined by the width of the sound beam

A

Lateral resolution
Angular
Transverse
Azimuthal

42
Q

answers the following question: are the reflections on the image created from structures directly in the imaging plane or from structures that lie above or beneath the imaging plane

A

Slice thickness resolution

elevational resolution

43
Q

Most important operational parameter associated with an ultrasound “movie” is the systems ability to create numerous frames each second
-determined by
sound’s speed in the medium
the depth of imaging
-units= hertz

A

Frame rate

44
Q

“accuracy in time”
the ability to precisely position moving structures from instant to instant
-excellent when the system produces many frames per second,and substandard when it produces few frames per second
-determind by frame rate

A

Temporal resolution

45
Q
A

Pixel

46
Q

derived from the term BInary digiT, is the smalles amount of computer memory, bistable , having a value of 0 or 1

A

Bit

47
Q

the manipulation of image data before storage in the scan converter

  • controlled by the sonographer
  • alters the image data forever and cannot be reversed or undone
A

preprocessing

48
Q

the manipulation of image data after storage in the scan converter

  • controlled by the sonographer
  • occurs after A-to-D conversion (digitization) and storage,
  • all changes can by reversed
  • any alterations to a frozen image
A

postprocessing

49
Q

a method of reporting the extent to which a signal can vary and still be accurately measured
Units= decibels(dB)
-a comparison, ratio or relative measurement between largest and smallest signals

A

Dynamic range

50
Q

the frequency of sound created by the transducer and transmitted into the body

A

fundamental frequency

51
Q

twice the fundamental frequency

A

Harmonic frequency (second harmonic frequency)

52
Q

the image created by processing reflections that have the same frequency as the transmitted sound

A

fundamental image

53
Q

the image created by processing reflections that are twice the fundamental frequency

A

harmonic image

54
Q

proportional or symmetrical, _____systems respond in and even manner

A

Linear behavior

55
Q

means irregular or disproportionate, behaves unevenly

A

nonlinear behavior

56
Q

indicates the volume of blood moving during a particular time
answers the question of “how much”
UNITS= volume divided by time (liters/min)

A

Flow

Volume flow rate

57
Q

Indicates the speed or swiftness of a fluid moving form one location to another
answers the question of “how fast”
UNITS= distance divided by time (cm/s)

A

Velocity

58
Q

occurs when blood moves with a variable velocity.
Blood accelerates and decelerates as a result of CARDIAC CONTRACTION; therefore, it commonly appears in arterial circulation

A

Pulsatile flow

59
Q

occurs when blood moves with a variable velocity.

Blood accelerates and decelerates as a result of RESPIRATION;therefore, it often appears in the venous circulation

A

Phasic flow

60
Q

occurs when a fluid moves at a constant speed or velocity.

Present in the venous circulation when individuals stop breathing for a brief moment

A

Steady flow

61
Q

when the flow streamlines are aligned and parallel
Characterized by layers of blood that travel at individual speeds
Commonly found in Normal physiological states

A

Laminar flow

62
Q

Characterized by chaotic flow patterns in many different directions and at many speeds.
The streamlines are often obliterated

A

Turbulent flow

63
Q

Pressure related to the weight of blood pressing on a vessel measured at a height above or below heart level
Units-mmHg same as blood pressure

A

hydrostatic pressure

64
Q

the highest Doppler frequency or velocity that can be measured without the appearance of aliasing

A

Nyquist limit (Nyquist frequency)

65
Q

the routine and periodic evaluation of an ultrasound system to guarantee optimal image quality
Must be performed periodically and routinely

A

Quality assurance

notes (2 decks)

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