chapter 1-3 Flashcards
(121 cards)
1
Q
frequency
A
cycles per second hertz
2
Q
amplitude
A
Measures from middle or undisturbed, value to the maximum value
3
Q
wavelength
A
distance or length of one complete cycle
4
Q
human hearing
A
20hz-20kHz
5
Q
high frequency
A
more cycles per second- better resolution but less penetration
6
Q
lower frequency
A
less cycles per second- less resolution but more penetration
7
Q
Pulse waves
A
pulse allow the ultrasound crystals to “talk” during the generation of sound and to “listen” between pulses
8
Q
Unrelated
A
Two items that are not associated
9
Q
related
A
two items that are associated or affiliated. Does not have to be specific
10
Q
Directly related or directly proportional
A
two items that are associated such that when one item increases, the other increases. lower left to upper right
11
Q
inversely related or inversely proportional
A
one item increases, the other decreases. upper left to lower right
12
Q
reciprocal relationship
A
two numbers with a reciprocal relationship are multiplied together the result is 1. when one increases the other decreases
13
Q
units of length
A
distance, circumference: cm, feet
14
Q
units of area
A
cm2, ft2
15
Q
units of volume
A
cm3, ft3
16
Q
positive exponents has a value
A
greater than 10
17
Q
negative exponents has a value
A
less than 1
18
Q
exponents of zero has a value
A
Between 1 and 10
19
Q
if we speak of frequency
A
talking about MEGAhertz
20
Q
if we speak about period
A
talking about MICROseconds
21
Q
tissue is also known as
A
media-medium
22
Q
sound is a
A
mechanical wave
23
Q
compressed
A
squeezed together
24
Q
rarefield
A
stretched apart
25
sound travels in
a straight line
26
sound waves are
Longitudinal waves
27
Acoustic propagation propereties
effects of the medium upon the sound wave
28
biologic effects
effects of thee sound wave upon the biologic tissue through which it passes
29
what are the three acoustic variables
pressure, density, distance
30
Pressure
concentration of force in an area
31
what are the units of pressure
Pascals (Pa)
32
Density
concentration of mass in a volume
33
what are the units of density
kg/cm3
34
Distance
measure of particle motion
35
what are the units of distance
cm, feet, miles
36
sound waves are also known as
acoustic waves
37
Transverse waves
perpendicular to the direction that the wave propagates
38
longitudinal waves
particles move in the same direction that the wave propagates.
39
sound is what kind of wave?
Longitudinal wave
40
in-phase waves
when their peaks occur at the same time and at the same location. "in-step"
41
out-of-phase
their peaks occur at different times, so do their troughs. "out-of-step"
42
interference
waves lose their individual characteristics at that moment and combine to form a single wave
43
constructive interference
wave is larger than either of its comonents
44
destructive interference
resultant wave is smaller than one of its comonents
45
both constructive and destructive interference occur when
frequencies of the wave differ
46
parameters
describe features of a sound wave
47
source
a sound wave is the ultrasound system and transducer
48
Period
is the time it takes a wave to vibrate a single cycle
49
units of Period
time, microseconds,seconds, hours, days
50
Typical value of Period
0.06-0.5 Microseconds
6x10^-8 to 5x10^-7
0.06 to 0.5 micros
0.00000006 to 0.0000005 seconds
51
Period is Determined by
sound source
52
can a Sonographer adjust Period?
NO
53
Frequency
the number of particular events that occur in a specific duration of time. the number of cycles that occurs in one second
54
what are the units of frequency
per second, 1/second=1 hertz
1,000 cycles/second=1 kHz
1,000,000 cycles/second=1 MHz
55
Typical value of Frequency
2 MHz-15MHz
2 million-15 million per second
56
Frequency is determined by
sound source
57
is Frequency adjustable?
NO
58
Frequency of infrasound
less than 20 Hz
59
Frequency of Audible sound
between 20 Hz and 20 KHz
60
Frequency of Ultrasound
Greater than 20 KHz (20,000Hz)
61
Frequency is important to ultrasound because
it affects penetration and image quality
62
Period and frequency are
inversely related to each other
63
period and frequency have a specific relationship called
reciprocal
64
Hertz means
events per seond
64
What are the three Bigness parameters
Amplitude, Power, Intensity
65
Amplitude
Bigness of a wave.
Difference between the maximum value and the average or undisturbed value of an acoustic variable. Difference between the minimum value and the average value of the acoustic variable
66
Units of Amplitude
Pressure- Pascals
Density- g/cm3
Particle motion- cm, inches-any distance
Decibels (dB)
67
typical values of Amplitude
1 million pascals (1 MPa) - 3 million pascals ( 3 MPa)
68
Amplitude is determined by
sound source
69
Can amplitude be adjustable?
Yes, allows the Sonographer to alter initial amplitude of a wave
70
Power
rate of energy transfer or the rate at which work is performed
71
Units of Power?
Watts
72
What is the typical values of Power?
0.004-0.090 watts
(4 - 90 milliwatts)
73
Amplitude and power are related how?
describe the size or magnitude of a wave.
74
squared
number is multiplied by itself
75
Power is determined by?
Sound source
76
is Power adjustable?
Yes, Allows Sonographer to alter the initial power of a wave
77
Intensity
concentration of energy in a sound beam
78
what are the units of intensity?
Watts/square centimeter, W/cm2
watts form power and cm2 from beam area
79
what are the typical values of intensity?
0.01-300 W/cm2
80
how is intensity determined by?
sound source
81
Is intensity adjustable?
Yes, alters the initial intensity of a wave
82
intensity formula
intensity (w/cm2)=power(w) / area(cm2)
83
Amplitude, power, and intensity describe what?
magnitude or strength of a wave. Directly Related
84
is intensity proportional to power?
YES
85
relationship between intensity and amplitude?
intensity is proportional to the wave's amplitude squared
86
Wavelength
distance or length of one complete cycle
87
units of a wavelength
mm, meters, or any other unit of length
88
typical value of wavelength
0.1-0.8 mm
89
Wavelength is determined by
BOTH the Source and the Medium
90
can you adjust wavelength?
NO
91
in soft tissue, sound with a frequency of 1 MHz has a wavelength of
1.54 mm
92
sound with a frequency of 2 MHz has wavelength of
0.77 mm in soft tissue
93
Wavelength formula
wavelength (mm) =1.54 mm/milliseconds/ frequency (MHz)
94
Shorter wavelengths are created by
high frequency sound
95
higher quality images have
greater detail
96
Propagation speed
rate at which a sound wave travels through a medium
97
what are the units of Propagation speed
meters per second, mm/ms, or any distance divided by time
98
what are the typical values of propagation speed?
500 m/s-4000 m/s depending on the tissue
99
propagation speed is determined by
medium through which the sound is traveling
100
is propagation speed adjustable?
NO
101
Biologic medium is called
soft tissue
102
the speed of sound in soft tissue is
1,540 m/s
1.54 mm/ms
1.54km/s
1 mile per second
103
sound travels fastest in
solids
104
sound travels slower in
liquid
105
sound travels slowest in
gases
106
Speed formula
speed (m/s) = frequency (Hz) x wavelength (m)
107
Two characters of Medium affect speed of sound
stiffness, density
108
Stiffness
ability of an object to resist compression
109
how does stiffness affect speed?
stiffness and speed are directly related
110
Bulk modulus
stiffness
111
Elasticity and compressibility are
the opposite of stiff
112
how does density affect speed?
Density and speed are inversely related
113
Stiffness has the greatest influence on
speed
114
sound travels slowly through
air
115
slowest to fastest propagation speeds
air
lung
fat
soft tissue/blood
tendon
bone
116
Pulse duration
Actual time from the start of aa pulse to the end of that pulse. Single transmitted, talking or on time
117
Units for pulse duration
Time: Microseconds
118
typical values of pulse duration
0.3-2.0 microseonds
119
pulse duration is determined by
sound source
120
is pulse duration adjustable?
NO
