BASICS
Sound waves are _______ and _______ waves.
MECHANICAL LONGITUDINAL
What are the three types of attenuation?
Absorption
Reflection
Scattering
In order for a crystal to have piezoelectric properties, it must first be ________.
Polarized
The pulser only functions during ______.
Transmission
What happens to wavelength when there is a positive Doppler shift?
Wavelength decreases
Longitudinal waves travel ______ to the direction of the wave.
parallel
The __________ the path length (depth) the greater the amount of attenuation.
The PZT thickness is _____ the wavelength.
1/2
What function of the receiver affects the signal after it has returned to the patient, therefore reducing patient exposure?
Amplification
The Doppler equation
Doppler frequency = 2 x F x V x cos/c
What ACOUSTIC Parameters are adjustable?
amplitude, power, and intensity
In order for reflection to occur, there must be a mismatch in ___________.
acoustic impedance
Backing material results in short ___ and better _____ resolution.
Short SPL and better axial resolution
When the signal is much stronger than noise.
High signal to noise ratio
An angle of 0 degrees has a cosine of
1
The number of pulses per second is ...
PRF
This type of scattering occurs when a structure is much smaller than the wavelength.
Rayleigh scattering
The frequency of a transducer is determined by:
Thickness of PZT
Speed of sound of the PZT
Which receiver function allows the sonographer to create a uniform image?
Compensation
Nyquist limit = PRF/2
Which PULSE parameters are affected by depth?
PRP, PRF, DF
Refraction occurs when these two criteria are met.
Change in speed of sounds
Oblique incidence
A low-frequency transducer will have ______ beam divergence in the far field than a high-frequency transducer.
more
Which receiver function allows the sonographer to adjust the displayed gray scale?
Compression
The ability to select the exact location where velocities are measured.
Range resolution