9 Ultrasound Imaging

Reflectivity

________ is zero when the acoustic impendences are equal to one another.

Blood flow

________ is the best example of the functional information that an ultrasound can show.

Acoustic impedance

________ is denoted by the letter Z.

Sector transducers

________ have an image shaped like a pie slice.

Intensity

________ is the square of the pressure.

Pm

________ is the maximum pressure intensity and amplitude (kPa)

Ω

________ is the frequency (rad /s) or 2pif where f is frequency (Hz)

Sound

________ is a mechanical pressure wave.

Particles

________ vibrate back- and- forth with a "zero "net movement in ultrasound.

B mode imaging

________ is formed by combining multiple A- mode lines to form a frame.

Doppler mode

________ is a 2- D plot with an overlay.

new interface

The reflecting and refracting at a(n) ________ during ultrasound is due to the acoustic impedance.

Transmittivity

________ is between zero and positive 2.

X axis

________ is time and y axis is amplitude.

K

________ is the wave number or the propagation constant (1 /m)

degree phase shift

A negative value for R indicates a 180 ________ (flip over x- axis); this affects phase shift, but not amplitude or anything else.

material density

Ρ is the average ________ (kg /m^3)

Units of acoustic impedance

________ are kg /m^2* s.

Acoustic wave intensity

________ is used to measure the power in the wave.

Audible waves

________ have a frequency of 20 Hz to 20 kHz.

Transmittivity

________ (T) is transmitted pressure over initial presssure.

Sound

________ is a longitudinal mechanical wave, which means the wave goes out and comes back along the same line.

K

________ is the compressibility constant of the material (ms^2 /kg)

Sector transducers

________ allow imaging through a narrow sonographic window in ultrasounds.

True

True or false, ultrasound imaging is non-ionizing

True

True or false, ultrasound imaging shows anatomical and functional info

False

True or false, ultrasounds can handle a big difference in density (i.e

A-mode

An imaging mode of ultrasound, where the amplitude of returning signal is returned and plotted; measures one line at a time

B-mode

An imaging mode of ultrasound, where A-line the a line plot of amplitude is shown as brightness over a certain distance

M-mode

An imaging mode of ultrasound where a plot of A-line, converted to brightness, and then repeated over time; shows motion; the plot is position vs time

Doppler

An imaging mode of ultrasound; if the object is moving then the returning wave will change, and that change in frequency is measured as velocity; color overlays are used to show velocity of flow and direction

Particle velocity

How fast a particle is moving back and forth, not wave speed

Refresh rate

Numbe of frames drawn per second (1/time of frame)

Sector

Ultrasound probe best for large structures that are deep in the tissue

Linear

Ultrasound probe best for imaging small structures that works best for structures just beneath the skin

Curved

An array ultrasound probe that combines sector and linear formats, best for a broad sonographic window