Flashcards in Transducers Deck (30):
Beam based imaging is what kind of resolution?
Axial resolution is based on what?
SPL - spatial pulse length
What were the transducers of the past made of?
single crystal or element
How are images formed?
scanning , sweeping and steering of the beam through the tissue
many images - frames within a second
REAL TIME SONOGRAPHY
Images are called....
What are the different types of transducers?
annular phased array
linear array (sequenced and phased)
First transducers were created in the...
What is a mechanical transducer?
MOTOR hooked up to a single piece of PZT
motor moves the ONE singular circular disc shaped crystal
produces a sector shaped image
What are the characteristics of the mechanical transducer crystal?
What kind of image does a mechanical transducer produce?
fan or sector shape
What moves the PZT in the mechanical transducer?
the motor - back and forth
What kind of focus the mechanical transducer have?
conventional (mechanical, fixed)
fixed focal depth
internal curvature of the PZT
acoustic lens - external focuses the beam
How is the mechanical transducer beam steered?
by the motor
a defective crystal destroys the entire image - because there is only one
What is the annular phased array?
crystal: multiple ring shaped elements
concentric rings: inner - shallow focus, outer - deep focus
multifocus in all planes at all depths
What kind of steering do annular arrays have?
may limit the life due to moving parts
design limits multi capabilities during doppler
Annular Phased Array : steering is done ___________, focusing is _________
With an annular what happens if you damage one crystal?
What is a modern transducer?
collection of active elements in a single transducer
elements are connected to the WIRE
each element has its own wire
What is a linear array?
linear segmental, switched or sequential array
NO beam steering
pulses send down straight lines
finish slide 33
which transducer has a large footprint?
Can the image be wider than the linear array transducer?
What kind of image does a linear array create?
How does the linear array work
defective crystal causes band dropout/black line
a few elements (3-10) are fired at the same time in GROUPS
What is the difference between early and modern models of linear array?
early- fixed focused - no steering
modern - electronic transmit focusing and receive focusing - electronic steering available
What is the linear Phased array?
sector or vector array
adjustable or multi focus
multiple elements each with electronic circuitry
ALL of the elements are fired in various patterns
crystal damage - black line dropout
What kind of steering and focus do the linear phased array have?
What is the shape of the image for the linear PHASED array?
how does the linear phased array deal with focus?
curved signals due to the time delays with the phasing tells it to focus
the slopes " " know how to steer the beam
what is the beam former?
electronics that create the patterns of slope (steering) and curvature (focus)
incredible short time delays to create these patterns
IN the MACHINE - tells the transducer what to do
**creates the focusing**