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DMS Physics :!: > Vocab 1 & 2 > Flashcards

Vocab 1 & 2 Flashcards

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1
Q

Sonography

A

medical two-dimensional, cross-sectional and three-dimensional anatomical and flow imaging using ultrasound.

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2
Q

Ultrasound

A

sound having a frequency greater than what humans can hear, that is greater than 20kHz (20,000 Hz).

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3
Q

Image

A

a reproduction, representation, or imitation of the physical form of a person or thing.

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4
Q

Transducer

A

a device that converts energy from one form to another.

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5
Q

Pulse-Echo Technique

A

ultrasound imaging in which pulses are reflected and used to produce a display.

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6
Q

Gray-Scale

A

a range of brightness between white and black.

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7
Q

Scan Line

A

a line produced on a display that represents ultrasonic echoes returning from the body.

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8
Q

Linear Image

A

an anatomical image presented in a rectangular format.

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9
Q

Sector Image

A

an anatomic image presented in a pie slice-shaped format.

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10
Q

Doppler Effect

A

is a change in frequency caused by motion of reflectors.

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11
Q

Color-Doppler Display

A

the representation of two-dimensional, real-time Doppler-shift information superimposed on a real-time, gray scale, anatomical, cross-sectional image.

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12
Q

Spectral-Doppler Display

A

the presentation of Doppler information in a quantitative form. Visual display of Doppler spectrum.

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13
Q

Wave

A

a traveling variation of one or more quantities.

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14
Q

Sound

A

a mechanical, longitudinal traveling wave in which particles in the medium move.

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15
Q

Acoustic Variables

A

sound wave variations of one or more quantities such as pressure, density, temperature or particle motion.

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16
Q

Vacuum Matter

A

the absence of matter (no matter = no sound)

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17
Q

Electromagnetic Waves

A

waves that travel at the speed of light and don’t need a medium for propagation (light, microwaves, X-Rays, TV and radio waves.)

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18
Q

Mechanical Waves

A

waves that are categorized by the direction of the displacement of individual particles in the medium, either transverse or longitudinal.

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19
Q

Transverse Wave

A

a wave in which particles in the medium vibrate perpendicular or “transverse” to the direction of the wave motion.

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20
Q

Longitudinal Wave

A

a mechanical compressional wave in which particles in the medium vibrate parallel to the direction of the wave motion.

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21
Q

Cycle

A

a completion of one compression and one rarefaction.

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22
Q

Compression

A

a region of high pressure and density in a sound wave.

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23
Q

Rarefaction

A

a region of low pressure and density in a sound wave.

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24
Q

Frequency

A

a number of cycles per second. Hz = 1 cycle/sec Freq(MHz)=PropSpeed(mm/us)/Wavelength(mm) or 1/Period(us)

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25
Q

Period

A

the time it takes for one cycle to occur (μs). Period(us)=1/Freq(MHz)

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26
Q

Wavelength

A

the length of space (distance) over which a cycle occurs (mm). Wavelength(mm)=PropSpeed(mm/us)/Freq(MHz)

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27
Q

Stiffness

A

(hardness) is the resistance of a material to compression.

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28
Q

Propagation Speed

A

the speed at which a wave moves through a medium (m/s, km/s, mm/μs). Prop Speed (mm/us)=Wavelength(mm)xFreq(MHz)

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29
Q

Harmonics

A

frequencies that are even and odd multiples of fundamental or operating frequency.

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30
Q

Pulse

A

a few cycles of ultrasound separated in time by gaps of no ultrasound.

31
Q

Pulse Duration

A

the time for one pulse to occur.

PD(us) = Period (us) x # of cycles in pulse

32
Q

PRF

Pulse Repetition Frequency

A

the number of pulses occurring in one second. (kHz, Hz)

PRF (kHz) = 1/PRP (ms)

33
Q

PRP

Pulse Repetition Period

A

the time from the beginning of one pulse to the beginning of the next one. (ms, μs)
PRP (ms) = 1/PRF (kHz)

34
Q

DF

Duty Factor

A

fraction of time that pulsed ultrasound is on. (Unitless or %)
DF(unitless) = PD(us) / PRP (us)

35
Q

SPL

Spatial Pulse Length

A

the length of space that a pulse takes up. (mm)

SPL(mm) = wavelength(mm) x # of cycles in pulse

36
Q

Bandwidth

A

the range of frequencies contained in a pulse.

37
Q

Fractional Bandwidth

A

bandwidth divided by operating frequency.

FB = Bandwidth / Operating Freq.

38
Q

Operating Frequency

A

preferred (maximum efficiency) frequency of operation of a transducer. Unit: MHz

39
Q

Quality Factor

A

the reciprocal of fractional bandwidth (operating frequency divided by bandwidth). Unitless
QF = Operating Freq / Bandwidth

40
Q

Amplitude

A

the maximum variation that occurs in an acoustic variable (pressure, density, temperature, particle motion). Units: Pa, g/cm3, cm, dB, etc.)

41
Q

Intensity

A

the rate at which energy passes through a unit area. Unit: W/cm2, mW/cm2
Intensity (W/cm2) = Power (Watts) / Area (cm2)

42
Q

Power

A

the rate of doing work. Unit: Watts

43
Q

Energy

A

the capability to do work. Unit: Joule (J)

44
Q

Attenuation

A

the weakening of sound as it propagates. Unit: dB

45
Q

Attenuation Coefficient

A

the rate at which the sound decreases in amplitude and intensity as it moves through a medium. Unit: dB/cm
Atten Coeff = 0.5dB/cm x Freq (MHz)

46
Q

Reflection

A

echo or a portion of sound returned from a media boundary. OR is the sound moving in the opposite direction after encountering a boundary between 2 media.

47
Q

Absorption

A

conversion of sound to heat.

48
Q

Scattering

A

diffusion or redirection of sound in several directions upon encountering tissue interfaces and heterogeneous tissues.

49
Q

Scatterer

A

an echo-generated structure.

50
Q

Echoes

A

reflected & scattered sound waves.

51
Q

Incident Sound

A

the initial sound prior to hitting a boundary between 2 media.

52
Q

Reflected Sound

A

the sound moving in the opposite direction of the incident sound after encountering a boundary between 2 media.

53
Q

Transmitted Sound

A

the sound that continues to the next boundary after encountering a boundary between 2 media.

54
Q

Incident Intensity

A

the strength of the initial beam prior to hitting a boundary between 2 media.

55
Q

Reflected Intensity

A

the strength of the beam moving in the opposite direction of the incident sound (or beam) after encountering a boundary between 2 media.

56
Q

Transmitted Intensity

A

the strength of the beam that continues to the next boundary after encountering a boundary between 2 media.

57
Q

Impedance

A

the acoustic resistance to sound traveling in a medium. Unit: rayls
Impedance (rayls) = density (kg/m3) x Prop Speed (m/s)

58
Q

Perpendicular Incidence

A

sound direction that is perpendicular to the boundary between media.

59
Q

Incident Reflection Coefficient

IRC

A

the fraction of incident intensity that is reflected. Unitless, %
IRC = Reflected Intensity (mW/cm2) / Incident Intensity (mW/cm2)

60
Q

Intensity Transmission Coefficient

ITC

A

the fraction of incident intensity transmitted into the second medium. Unitless, %
ITC= 1- IRC or ITC= Transmitted Intensity (mW/cm2) / Incident Intensity (mW/cm2)

61
Q

Incident Angle

A

the angle between incident sound direction and a line perpendicular to the media boundary.

62
Q

Reflected Angle

A

the angle between the reflected sound direction and a line perpendicular to the media boundary.

63
Q

Transmission Angle

A

the angle between the transmitted sound direction and a line perpendicular to the media boundary.

64
Q

Oblique Incidence

A

the direction of travel of the incident sound wave that is NOT perpendicular to the boundary between the media.

65
Q

Refraction

A

a change in the direction of sound when it crosses a boundary (from Latin term “to turn aside.”)

66
Q

Specular Reflectors

A

reflectors which occur when thebeamis small compared to the boundary (wavelength is small to the boundary.)

67
Q

Nonspecular Reflectors

A

reflectors which occur when thebeamis large compared to the boundary (wavelength is large to the boundary.)

68
Q

Backscatter

A

sound scattered back in the direction from which it originally came.

69
Q

Speckle

A

a form of acoustic noise in sonographic imaging.

70
Q

Interference

A

produced when several echoes are generated simultaneously within the pulse as it interacts with the scatterers.

71
Q

Constructive Interference

A

occurs when the echoes arrive at the transducer in such a way that they reinforce each other.

72
Q

Destructive Interference

A

occurs when the echoes arrive at the transducer in such a way that they partially or totally cancel each other.

73
Q

Contrast Agents

A

a liquid suspension intravenously injected into the circulatory system to increase echogenicity.

74
Q

13μs/cm Rule

A

13 microseconds of round-trip travel time are required for each cm of distance from the transducer to the reflector.

DMS Physics :!: (4 decks)

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