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Ultrasound physics Ch 1-3
Diagnostic Medical Sonography
84
Physics
Undergraduate 1
05/21/2011

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Term
x-axis
Definition
The horizontal axis
Term
y-axis
Definition
vertical axis
Term
unrelated
Definition
two items that are not associated
Term
directly related
Definition
Two items that are associated such that one item increases, the other increases
Term
Related
Definition
Two itemss that are associated or affiliated
Term
inversely related
Definition
Two items are associated such that when one item icreases, the other decreases
Term
true
Definition
A number followed by the word percent is unitlesss
Term
Billion
Definition
Giga
Term
million
Definition
mega
Term
thousand
Definition
kilo
Term
hundred
Definition
hecto
Term
ten
Definition
deca
Term
tenth
Definition
deci
Term
hundredth
Definition
centi
Term
thousandth
Definition
milli
Term
millionth
Definition
micro
Term
billionth
Definition
nano
Term
Mechanical & longitudinal
Definition
Sound waves are what?
Term
Bioeffects
Definition
The effects of the sound wae upon the biologic tissue through which it passes
Term

acoustic propagation

 properties

Definition

The effects of the medium upon the

 sound wave

Term
  • Pressure
  • Density
  • Distance
Definition
Three acoustic variables
Term
Pressure
Definition

Concentration of force in an area

pascals(Pa)

 

Term
Density
Definition

Concentration of mass in a volume

kg/cm³

Term
Distance
Definition

Measure of particle motion

cm,feet,mile

Term
  • Period
  • Frequency
  • Amplitude
  • power
  • Intensity
  • Wavelength
  • Propagation speed
Definition
Seven acoustic parameters
Term
In-phase waves
Definition
Two waves that peaks occur at the same time and at the same location
Term
Interference
Definition
These waves lose theri individual characteristics at that moment and combine to form a single wave
Term
Out-of-phase waves
Definition

Two waves that peaks occur at

different times

Term
Constructive Interference
Definition
The interference of a pair of in-phase waves results in the formation of a single wave of greater amplitude than either of its components
Term
Destructive Interference
Definition
The interference of a pair of out-of-phase waves results in the formation of a single wave of lesser amplitude than either of its components
Term
Parameters
Definition
Describe features of a sound wave
Term
Ultrasound system and transducer
Definition
What is the source of a sound wave?
Term
Tissue
Definition
What is the medium?
Term
Period
Definition

the time it takes a wave to vibrate a

 single cycle

Term

Time

Sec,ms,hours,or days

Definition
Period is reported in what units?
Term
source
Definition
Period is determined by what?
Term
No
Definition
Can period be adjusted?
Term
Frequency
Definition
The number of particular events that occurs in a specific duration of time
Term
2 MHz - 10 MHz
Definition
In clinical imaging, frequency ranges approximately what?
Term
source
Definition
Frequency is determined by what?
Term
no
Definition
Can the frequency be adjusted?
Term
less than 20 Hz
Definition
infrasound
Term
between 20 Hz & 20 kHz
Definition
Audible sound
Term
greater than 20 kHz
Definition
ultrasound
Term
It affects penetration and image quality
Definition
Why is frequency important?
Term
Inversely related
Definition
How are frequency and period related?
Term
Reciprocals
Definition
Period and frequency are also what?
Term
  • Amplitude
  • Power
  • Intensity
Definition
Three parameters describe the size, or magnitude, or strength of a sound wave
Term
Amplitude
Definition

the "bigness" of a wave

 It is the difference between the maximum value and the average or undisturbed value of an acoustic variable

Term
1 million pascals to 3 million pascals
Definition
In clinical imaging, pressure amplitude ranges what?
Term
sound source
Definition
Amplitude is determined by what?
Term
Yes
Definition
Can amplitude be adjusted?
Term
Power
Definition

The rate of energy transfer or the rate at which work is performed.

Also describes "bigness" of a wave

Term
watts
Definition
Power has units of what?
Term
0.004 - 0.090 watts
Definition
In clinical imaging, typical powers range from what?
Term
sound source
Definition
Powere is determined by what?
Term
yes
Definition
Is power adjustable?
Term

They are proportional, directly related

Power=amplitude²

Definition
How are power and amplitude related?
Term
Intensity
Definition

The concentration of energy in a sound beam.

Also describes the "bigness" of a wave.

Term

watts/square centimeter

W/cm²

Definition
What is the units for intensity?
Term
0.01 - 300 W/cm²
Definition

In clinical imaging, intensity ranges

 from what?

Term
sound source
Definition
Intensity is determined by what?
Term
yes
Definition
is intensity adjustable?
Term
Power(W) / Area(cm²)
Definition
Intensity = ?
Term

intensity = power

(proportional)

Definition
how is intensity and power related?
Term
Wavelength
Definition
The distance or length of one complete cycle
Term

Meters

Any units of length

Definition
units of wavelength?
Term
Both the source and medium
Definition
What is wavelength determined by?
Term
No
Definition
can wavelength be adjusted?
Term
Inversely related
Definition
How are wavelength and frequency related?
Term
1.54 mm
Definition
In soft tissue, frequency of 1 MHz has a wavelength of what?
Term

Wavelength =

1.54 (mm/microsecond)/Frequency (MHz)

Definition
What is the rule that defines the relationship between frequency and wavelength of sound in soft tissue?
Term
Shorter wavelength sound produces higher quality images with greater detail.
Definition
Why is wavelength important in diagnostic ultrasound?
Term
Propagation speed
Definition
the distance that a sound wave travels through a medium in 1 second
Term
meters per second
Definition
units of propagation speed?
Term
500 m/s to 4000 m/s
Definition
In the body, the speed of sound ranges from what?
Term
medium only
Definition
Speed is determined by what?
Term
no
Definition
is speed of sound adjustable?
Term
1540m/s or 1.54 mm/µs
Definition
What is the speed of sound in soft tissue?
Term
  • stiffness
  • density
Definition
What two characteristics of a medium affect the speed of sound?
Term
stiffness
Definition
the ability of an object to resist compression
Term
Density
Definition
Describes the relative weight  of a material, weighs more
Term
directly related
Definition
how are stiffness and speed related?
Term
Inversely related
Definition
How are density and speed related?
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