practice exam Flashcards
Which transducers fires the elements in groups?
linear sequenced array
What is the highest attenuator in U/S?
air
What has the highest prop velocity?
bone
What is the intensity equation?
Power/area
Which of the following has the lowest intensity?
a. SPTP
b. SATP
c. SPTA
d. SATA
SATA
What is the definition of the beam uniformity ratio?
SP/SA
Ultrasound attenuates an average of ___________________dB/cm of
travel for each megahertz of frequency.
0.7
If medium 2 impedance is equal to medium 1 impedance:
100% transmission
What is the measurement for impedance?
Raylz
- A decibel (dB) describes the:
a. Ratio of two sound intensities
b. Sum of two sound intensities
c. Amount of scattering
d. Velocity of the sound wave
Ratio of 2 sound intensities
The attenuation coefficient of sound in soft tissue can be defined by what equation?
freq/2
Diffraction refers to
spreading out of the beam
The echoes are stored before final display by the:
Scan converter
What component of the ultrasound system contains the digital-to analog converter?
Scan converter
How many different shades of gray can the human eye discern at one
time?
about 100
The spatial resolution capabilities of the system are mainly functions of the:
tx
What is infrasound?
sound with a frequency less than 20 Hz
What is audible sound?
s in the frequency range of 20 to 20,000 Hz
How dp you adjust the PRF?
by adjusting the depth
When is angle 2 less than angle 1
if speed of medium 2 is less than the speed of angle 1
What is propogation speed determined by?
Propagation speed is only determined by the medium (specifically stiffness and density
Unit for intensity
W/cm2 i
What testing device is used to measure acoustic output (intensity)
level?
hydrophone
radial resolution is another name for?
axial resolution
Axial resolution formula
1/2 SPL
In the most common type of transducers, the slice-thickness plane is focused by using?
a lens
What is the relationship of propogation speed and frequency?
unrelated, dont alter eachother
Which law describes the relationship between flow and the pressure
differential, viscosity, and length?
Poisuelles
M/C flow in the body
Laminar
