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87 Cards in this Set
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Give the formula for propagation speed

C= frequency * wavelength


Propagation speed is dependent on what?

The medium


If density increases what happens to the propagation speed?

decreases


Give the formula for wavelength

wavelength= c/ frequency


give the units for frequency

Hz or MHz


Give the units for Period

seconds or microseconds


Give the units for wavelength

meters or millimeters


Give the units for propagation speed

m/sec or mm/microsecond


Give the units for PRF

H or kHz


Give the units for PRP

seconds or microseconds


Give the units for Pulse Duration

seconds or milliseconds


Give the units for Duty Factor

Duty factor is unitless!


Give the units for SPL

millimeters


Give the units for Amplitude

Megapascals (MPa)


Give the units for Power

Watts or milliwatts


Give the units for Intensity

watts/cm^2


Give the units for the Beam Uniformity Ratio (BUR)

BUR is unitless!


Give the units for Attenuation

Decibels


Give the units for the attenuation coefficient

dB/cm


Give the units for Impedence

Rayls


Give the formula for SPL

SPL= n * wavelength
OR SPL= (n*c)/frequency 

Give the formula for Pulse Duration

PD= n * T


Give the formula for Duty Factor

DF= (PD/PRP) * 1000
OR DF= (PD*PRF)/1000 

Give the formula for Intensity

Intensity= Power/Area


Describe the Temporal average intensity to the Peak average intensity

Intensity TA = Intensity PA * DF


Give the formula for Beam Uniformity Ratio

BUR= SP/ SA


Give the formula for Attenuation coefficient

Ac= 1/2 frequency


Give the formula for Attenuation

Attenuation= Ac * Length
OR Attenuation= 1/2frequency * length 

Give the formula for the Half Value Thickness Layer

HVTL = 3/ Ac
OR HVTL = 6/ frequency 

Give the formula for Impedence

Z= density * c


Give the formula for the Intensity Reflected Coefficient

IRC= [(Z2Z1)/(Z2+Z1)]^2


Give the formula for the Intensity Transmitted Coefficient

ITC= 1 IRC


Give the formula for Snell's Law

[sine incident angle/ sine transmitted angle]= c1/c2


Give the formula to solve for the distance of the reflector

D= 1/2 [c * time]
t represents round trip time 

The average round trip distance of a reflector can be solved using which rule?

13microseconds/1cm Rule
aka the rule of 13 

Define frequency

number of cycles per second


Define period

time it takes for one cycle to occur


Define wavelength

The length of one complete cycle


Define PRF

the number of pulses per second


Define PRP

Time from the begin of one pulse to the beginning of the next pulse


Define PD

time it takes for one pulse to occur


Define Duty Factor

Fraction of time the transducer is generating a pulse (when it's on)


Define SPL

Length of a pulse


Define Amplitude

Variation of a given sound wave, indicates strength


Define Power

Rate at which energy is transferred


Define Intensity

Rate at which energy passes through an area


Define the Beam Uniformity Ratio

unitless ratio that describes the distribution of the sound beam intensity


Define Attenuation

weakening of a sound beam


Define the Half Value Thickness Layer

distance intensity must travel to be reduced by half the original intensity


Define Backscatter

sound travels back in the direction it came from


How many pulses are in a pulsed wave cycle?

23


How many pulses are in a Doppler wave cycle

5 30


Describe the relationship between power, intensity, and amplitude

Power is congruent to Intensity
Power is congruent to Amp^2 Intensity is congruent to Amp^2 

Describe the purpose of Focusing a beam

Decreases the area of the sound beam therefore increases the intensity


Where is the Spatial Peak intensity found

At the beam center


What is the most common intensity used in pulsed wave?

SPTA


Where is SPTP used?

In continuous wave, is the highest intensity


What is the purpose of a hydrophone?

measures the intensity of a sound beam


When does a specular reflection occur?

When the wavelength is larger than the boundary and the surface is smooth


What kind of boundary does perpendicular incidence encounter?

A 90 degree angle


What kind of boundary does an oblique incidence encounter?

Any angle other than 90 degrees


Give the 3 criteria for Snell's Law

1. need 2 different c
2. need to hit at oblique angles 3. incident angle = reflected angle 

Give the 2 requirements for Refraction to occur

1. oblique incidence
2. different propagation speeds on each side of the boundary 

Refraction is strongly dependent on?

Impedence


What will cause scattering?

1. size of reflector is equal or less than the wavelength
2. a rough surface 

List the contrast agents used in the U.S

1. Definity
2. Imagent 3. Optison 

What are the purposes of contrast agents

1. improve lesion detection
2. improves weakened Doppler signals 

List the acoustic variables

1. Pressure
2. Density 3. Particle vibration 

Give the formula for NZL

NZL= (apeature)^2/(4*wavelength)
OR NZL= (aperature)^2*freq/4*c 

Give the formula for Q Factor

Q= operating freq./ Bandwidth


What is the purpose of damping material?

used to reduce number of cycles in a pulse to improve resolution


What is sacrificed with damping material

sensitivity


What is the damping material composed of?

epoxy resin and metal powders


What is another name for damping material?

Backing material


How thick are ultrasound elements typically?

0.21mm


Describe the relationship between crystal thickness and frequency

The thicker the crystal the lower the frequency
The thinner the crystal the higher the frequency 

Describe the matching layer in relation to the crystal wavelength

matching layer = 1/4 wavelength of the crystal


What determines the Near Zone Length?

aperature and operating frequency


What is another name for near zone?

Fresnel zone


Describe the relationship between NZL, aperature, and frequency

Increase aperature, increase NZL
Increase frequency, increase NZL 

What is another name for the far zone?

Fraunhofer zone


Describe the width of the transducer element at the end of the NZL and at double the NZL

End of NZL beam width= 1/2 transducer element width
Double NZL beam width = transducer element width 

Focusing can only be accomplished in what zone?

Fresnel zone aka near zone


Annular array transducers are __ steered and __ focused

mechanically steered, electronically focused


Define aperature

Size of the ultrasound element


Define apodization

outer elements are driven at lower amplitudes than inner elements to reduce grating lobes


Define matching layer

Placed in front of transducer to reduce reflection at the transducer/element interface
