• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/20

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

20 Cards in this Set

  • Front
  • Back

Reverse peizoelectric effect

generating mechanical strain from the applicationof an electrical signal to piezoelectric material

Direct Peizoelectric effect

generating electrical signal from the application of a mechanical strain (sound wave) applied to a peizoelectric material

Peizoelectric materials

Ceramic and crystalline materials with the capacity to generate electrical charge in response to applied mechanical stress

Relationship between frequency and:




- Wavelength


- Penetration


- Resolution

Higher frequency has:


- Shorter wavelength


- Greater penetration


- Greater axial resolution

Acoustic impedance

resistance to propagation of sound waves throughtissues




fixed property of tissues determined by mass density and propagation speedof sound in a specific tissue

Attenuation

Loss of energy as sound waves are transmitted through a medium




Due to:


- Absorption


- Deflection


- Divergence

Absorption

Loss of energy from the ultrasound beam transferred to the tissues in the form of heat

Deflection

Reflection, refraction, and scattering of energy within tissue

Divergence

Loss of the energy as the ultrasound beam widens and the same power is spread over a greater area

Doppler effect

Shift in frequency of sound wave due to relative motion between source and observer




- If source moving towards observer then higher frequency shift


- If source moving away from observer then lower frequency shift

Spectral doppler

Display of doppler velocities (y-axis) over time (x-axis)

Pulsed wave doppler

Emission of sound waves in pulses that allows measurement of doppler shifts at a specific area/depth

Pulse repetition frequency (PRF)

Cycle frequency pulsed wave doppler

Aliasing

Phenomenon with color doppler and pulsed wave spectral doppler whereby the direction/velocity of flow cannot be accurately determined

Nyquist limit

The doppler velocity at which aliasing occurs




= PRF/2

Continous wave doppler

Measures doppler velocities along the entire length of the ultrasound beam

Color flow doppler

Displays doppler shifts over a superimposed 2-d image




Pulse wave doppler from multiple small areas

Power flow doppler

Shows only information on velocity of flow but not direction




Useful for low flow states

Thermal index

Measure of U/S's thermal bio effects




Ratio of attenuated acoustic power at depth of interest to estimated power needed to raise tissue by 1 degree celcius

Mechanical index

Measure of potential for cavitation/micro mechanical damage