Module 1.1 : Transducer Evolution Flashcards
1
Q
Probe evolution
A
Single disc, mechanically steered, annular array, electronic array
2
Q
Mechanical transducers
A
-started out as thin disk shaped crystal 6-19mm in diameter
- fixed focal zone with varying configuration
+ linear translation
+ wobbler
+ oscillating element
+ oscillating mirror
3
Q
Linear translation
A
- oldest technology
- moved crystal assembly along track to SWEEP the tissue
4
Q
Wobbler
A
- fixed and element onto a motor that rotated back and forth to obtain field of view
- very popular type of probe that produced a SECTOR image
- fluid filled and moving parts risked production of air bubbles
5
Q
Linear field of view
A
- to achieve linear FOV probes use a reflector or acoustic mirror to direct the sound into the patient
- OSCILLATING MIRROR that moves with a stationary element
6
Q
Rotating wheel
A
- several crystals that spin and only pulse when the element passes the FOV
7
Q
Annular array
A
- biggest advances in transducer technology
- probe still mechanically steered you could electronically change the focus
8
Q
Annular array - focusing
A
- uses concentric disco to allow for the focusing of the beam
- changing the disc that is fired you changed the diameter which varies the focal depth
- wider th crystal the larger the distance to the focal point
9
Q
Annular array - limitation
A
- still has the same limitation for mechanically steered probes
- inherit to annular arrays was grating lobes
- grating lobes are low energy beams that radiate away from main axis and make artifact
+ grating lobes are called side lobes in single disk element
10
Q
Electronic arrays
A
- have multiple small elements aligned in linear rows
- 2nmain types
+ phased sector array
+ phased linear array ( and curved) - have wide bandwidths and need flexibility to perform many exams
11
Q
Electronic array - phasing
A
- uses nanosecond time delays to change when the voltage excites the crystal
- purpose to control the Beam using Huygens principle and allow for beam focusing snd steering
12
Q
Electronic arrays - focusing and steering
A
- accomplished with phasing of voltages
- steering of beam can help direct th sound at an Angle for sector array
- vector scanning is same as steering the beam
13
Q
Electronic arrays - phased sector array s
A
- all crystals (128) are fired at nearly the same time to steer beam across the face of the probe
- sector FOV can be as large as 90’ or as small as 30’ with the thought of scanning the ribs as reason for the shape
14
Q
Electronic arrays - linear arrays
A
- have relatively large footprints with 64-100 elements in a row
- FOV is rectangular shaped but can be trapezoidal
- no scan line divergence
- highenfrequencies
15
Q
Segmental sequencing
A
- group of crystals fired to crate a beam followed by a second group one crystal down
