Term
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Definition
| Two items that are not associated. |
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Term
| Directly related or directly proportional |
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Definition
| Two items that are associated such that when one item increases, the other increases. |
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Term
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Definition
| Two items that are associated or affiliated. The relationship does not have to be specified. |
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Term
| Inversely related or inversely proportional. |
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Definition
| Two items are associated such that when one item increases, the other decreases. |
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Term
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Definition
| When these two numbers are multiplied together they equal 1. |
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Term
| Increase by a factor means |
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Definition
| To multiply by that number. |
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Term
| Decrease by a factor means to |
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Definition
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Term
| What are the prefixes for billions and billionths? |
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Definition
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Term
| What are the prefixes for millions and millionths? |
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Definition
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Term
| What are the prefixes for thousands and thousandths? |
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Definition
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Term
| What are the prefixes for hundreds and hundredths? |
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Definition
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Term
| What are the prefixes for tens and tenths? |
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Definition
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Term
| What is scientific notation for 0.000001? |
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Definition
| ten to negative 6 or micro |
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Term
| When converting units if the unit gets larger the number must |
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Definition
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Term
| billion also written as 10 to the 9th power has the prefix |
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Definition
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Term
| Acoustic propagation properties |
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Definition
| the effects of the medium upon the sound wave |
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Term
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Definition
| the effects of the sound wave upon the biologic tissue |
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Term
| What does a sound wave carry? |
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Definition
| a type of wave that carries energy, not matter, from place to place |
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Term
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Definition
| vibration of a moving object |
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Term
| A sound wave is a series of |
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Definition
| compressions and rarefactions |
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Term
| Sound is what kind of wave? |
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Definition
| mechanical and longitudinal |
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Term
| The typical units for period are |
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Definition
0.06 to 0.5 micro senconds usec
which is the same as
0.6 x 10 to negative 7 to 5 x 10 to negative 7 |
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Term
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Definition
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Term
| Can period be changed by the sonographer? |
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Definition
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Term
| The units for frequency are |
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Definition
| hertz Hz same as per second |
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Term
| Frequency is determined by |
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Definition
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Term
| Typical units for frequency are |
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Definition
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Term
| A wave with a frequency exceeding 20,000 Hz or 20kHz |
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Definition
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Term
| Sound with a frequency between 20 Hz and 20,000 Hz |
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Definition
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Term
| Sound with frequencies less than 20Hz |
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Definition
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Term
| This "bigness" parameter amplitude may be expressed in |
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Definition
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Term
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Definition
| The rate that sound travels through a medium |
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Term
| Units for propagation speed |
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Definition
| m/sec or mm/us (micro second) |
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Term
| Propagation speed is determined by |
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Definition
the medium only
density and stiffness |
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Term
| Can the propagation speed be changed by the sonographer? |
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Definition
| No because it is determined only by the media |
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Term
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Definition
| when two waves overlap at the same location and time |
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Term
| Constructive interference |
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Definition
| In phase waves combine to form a wave greater than the original two waves |
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Term
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Definition
| out of phase waves interfere and cause the amplitude of the new wave to be less than the original waves |
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Term
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Definition
| The difference between the maximum value and the average or undisturbed value of an acoustic variable. |
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Term
| Units of amplitude can be any of the acoustic variables such as |
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Definition
pressure - pascals or density - g/cm cubed (3)
Particle motion - distance
dB decibels |
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Term
| Typical values of amplitude are |
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Definition
1 - 3 million pascals
same as 1 MPa to 3 MPa |
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Term
| Amplitude is initially determined by |
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Definition
| the sound source, however, amplitude decreases as sound propagates through the body. The rate at which amplitude decreases as sound propagates depends on the characteristics of both the sound wave and the MEDIUM. |
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Term
| Can the amplitude be controlled by the sonographer? |
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Definition
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Term
| What is peak to peak amplitude? |
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Definition
| The difference between maximum and minimum values of an acoustic variable. |
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Term
| The rate at which energy is performed is |
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Definition
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Term
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Definition
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Term
| The typical values for power are |
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Definition
| 0.004 to 0.090 watts (4 to 90 milliwatts) |
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Term
| Power is determined initially by |
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Definition
| the sound source. However power decreases as sound propagates through the body. |
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Term
| Can the sonographer adjust the power? |
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Definition
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Term
| Power is proportional to the amplitude |
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Definition
SQUARED
if the sonographer increases the amplitude of a wave by a factor of 3 the power is increased 9 fold 3 x 3 =9 AMPLITUDE SQUARED |
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Term
| If a sonographer decreases the amplitude of a wave to 1/2 of its original value how has the power changed? |
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Definition
| Power is proportional to the amplitude squared so the power is decreased to 1/4 or 25% of its original value. |
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Term
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Definition
| the concentration of energy in a sound beam |
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Term
| The units for intensity are |
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Definition
watts per square cm
watts from power and cm squared from beam area |
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Term
| Typical values for intensity are |
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Definition
| 0.01 to 300 watts/cm squared |
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Term
| Intensity is determined initially by |
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Definition
The sound source.
However, intensity changes as sound propagates through the body. The rate at which intensity changes depends on the characteristics of the medium and the shape of the sound beam. |
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Term
| Is intensity adjustable by the sonographer? |
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Definition
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Term
| Amplitude, power and intensity tend to be related how? |
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Definition
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Term
| Intensity is proportional to |
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Definition
power
If power doubles intensity doubles |
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Term
| Intensity is proportional to amplitude |
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Definition
squared.
If a waves amplitude is doubled the intensity is increased four times. |
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Term
| Power and Intensity are related to amplitude |
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Definition
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Term
| Mathematically intensity and power are |
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Definition
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Term
| This parameter is the only one determined by both the source and the medium. |
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Definition
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Term
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Definition
| the distance or length of one complete cycle. |
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Term
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Definition
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Term
| Typical values of wavelength are |
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Definition
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Term
| Wavelength is determined by |
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Definition
| both the source and the medium |
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Term
| Is wavelength adjustable by the sonographer? |
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Definition
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Term
| What is the relationship between wavelength and frequency? |
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Definition
| As long as the wave remains in the same medium they are inversely related. |
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Term
| What is the wavelength of 1 MHz sound in soft tissue? |
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Definition
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Term
| What is the rule that defines the relationship between frequency and wavelength of sound in soft tissue? |
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Definition
| Divide 1.54mm by the frequency in MHz |
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Term
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Definition
| the distance that a sound wave travels through a medium in 1 second. |
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Term
| Units for propagation speed are |
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Definition
| meters/second or mm/micorsecond or any distance divided by time |
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Term
| Typical values for propagation speed are |
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Definition
| 500 m/sec to 4000 m/sec depending on the tissue it is traveling through. |
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Term
| Propagation speed is determined by |
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Definition
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Term
| Is the propagation speed adjustable by the sonographer? |
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Definition
No
It is determined by the medium only |
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Term
| List the speed of sound in biologic tissue from slowest to fastest. |
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Definition
| lung > fat > soft tissue average > liver > blood > muscle > tendon > bone |
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Term
| The propagation speed of air |
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Definition
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Term
| Speed of sound in soft tissue (including blood) |
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Definition
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Term
| Propagation speed of tendon |
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Definition
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Term
| Propagation speed of bone |
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Definition
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Term
| Two characteristics determine the speed of sound in tissue they are |
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Definition
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Term
| Stiffness and speed are related how? |
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Definition
directly
if one goes up the other goes up |
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Term
| Density and speed are related how? |
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Definition
Inversely
If density goes up speed goes down |
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