Chapter 14 Flashcards
turns electric energy to acoustic
energy and vise versa
Transducer
creates and controls
the electrical signals sent to the transducer that
generate sound pulses.
Pulser and beam former
determines amplitude, PRP, and PRF
Pulser
determines the firing delay
pattern
Beam former
transforms the electrical signals from
the transducer into a form suitable for display
Receiver
presents processed data
Display
archives the ultrasound studies
Storage
maintains and organizes
the proper timing and interaction of the systems
components
Master Synchronizer
The _ creates electrical signals that
excite the transducer’s PZT crystals and
create sound beams.
Functions during _
pulser
transmission
Directly controls the amount of power entering the
patient
Pulser
The part of the beam former that determines:
PRF
PRP
Amplitude
Pulser
Transducer Output ranges from
0-100 volts
Changes in pulser voltage modify the
brightness of the entire image displayed
on the system’s screen.
The sonographer can adjust the _ of the pulser’s electrical
voltage spike
magnitude
When pulser voltage is low,
the element vibrates _ and a _ sound beam is
transmitted into the body. The
reflected echoes are _ and the image tends to be _
gently
weak
weak
dark
When pulser voltage is high,
the element vibrates _ and _ sound beams are sent into the body. The reflected echoes are _ and the image is _.
more forcefully
stronger
stronger
brighter
Pulser voltage AKA
Output gain Acoustic power Pulser power Energy output Transmitter output Power Gain- avoid using this
Is pulser voltage adjustable by sonographer?
Yes
Modifying transducer output changes
all the
pulses transmitted to the body.
The brightness of the entire image changes
Lower pulser voltages _ the
likelihood of bioeffects
minimize
Random and persistent disturbance that
obscures or reduces a signal’s clarity
Noise
Noise contaminates images with _
low-level,
undesirable information
_ is a comparison of the
meaningful information in an image (signal)
compared to the amount of contamination
(noise).
Signal to noise ratio
When transducer output is low, noise is (more or less) likely to degrade the image
More
An increase in output power =
increase in
signal-to-noise ratio
Better image
Do noise levels remain constant to change?
Remain constant
_ is the most common
way to improve the signal to noise ratio
Increasing output power
Pulse Repetition Period is determined by
the pulser
Is PRP adjustable by sonographer
Yes
_ determines maximum imaging depth
PRP
