basicas are interchangable between manufactureres
reduces scan time in a clinical setting
know your controls
Knobology
varies energy transmitted to patient
should be used at lowest level
ALARA limit
higher power=brighter image
Acoustic power/transmit power
operator controlled
determines electrical voltage to pulsar
low voltage=gentle PZT vibration
high voltage=forceful vibration
transmit power controls
creates electrical signals that excite the PZT crystals
only functions during transmission
operator controlled
0-500 volts
important in Bioeffects
Pulsar
0-500 volts
high =brighter image
also called output gain, accoustic power, energy output or transmitter output
Pulsar voltage
Thermal Index
Mechanical Index
Pulsar Standardization
random and persistant degradation
unwanted low level echoes
Noise
power increase raises ratio
quiality improves with increase
Signal to Noise ratio
determines time between voltage spikes
PRP Pulse repition Period
controlled by operator
pulser repitition
determines depth of scan
operator controlled
Pulse Repitition Period
PRP
continuous wave
vascular
Pulser single pulse
pulsed wave
imaging
Pulser numerous pulses
shorter listening time
shorter PRP
higher PRF
Shallow imaging
longer listening time
longer PRP
lower PRF
Deeper imaging
recieves the electrical spike from pulser and distributes to the active elements in an array transducer
used advanced microprocessor tech to produce digital format
Bean Former
proteects the electrical components in the reciever
Beam Former Switch
prepares information from returning echoes for display
5 functions
Reciever
Amplification
Compensation
Compression
Demodulation
Reject
5 reciever functions
first function
affects all signal quality
receiver gain
measured in dB
adjustable
Gain/Overall Gain knob
Amplification
controls degree of echo amplification or brightness or image
too much can fill artifactual echoes into a fluid structure
too little can negate echo information
Gain Overall Gain
creates and image of uniform brightness
known as TGC Time Gain Compensation
DGC Depth Gain COmpensation
sompensates for the sound wave as it weakens or attentuates
Compensation
operator controlled
sliders on console
structures will be same brightness regardless of depth
TGC
DGC
3rd function
keeps image grayscale content with range of human eye (20 shades)
keeps electrical signal level within accuracy range
called log compression or dynamic range (DR) most common
dB
operator controlled
Compression
relative term that compares on one signal to another
important in quantifying strenght of sound beams, electrical signal strenght and brightness of image
notatoin is logarithmic
Decibels dB
4th function
two part process that changes electrical signals in reciever into a more suitable form for the CRt or monitor
rectifies and smooths electrical signal
NOT adjustable
no effect on image
Demodulation
5th function
controls whether low level signals will be displayed
low leve signasl can be diagnostic or noise
called threshhold or suppression
operator controlled
Reject
Adjustable
all signals affected identically
entire image gets brighter or darker
Amplification overview
Adjustable
signals treated differently bases on reflective depth
images will be uniformly bright from top to bottom
Compensation Overview
Adjustable
Signals treated differently depending on strenght
changes grayscale mapping
Compression Overview
NOT adjustable
prepares electrical signals to be suitable for display
NO effect on image
Demodulatoin Overview
