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Where is the matching layer located?
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What is the purpose of the matching layer?
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TRANSDUCERS

CONSTRUCTION OF

QuestionAnswer
Where is the matching layer located? Between the patient's skin and the piezoelectric element.
What is the purpose of the matching layer? To even out the differences in their impedence
List the last three components in order from the outside in... Matching material, transducer element, backing material
The bigger the impedence the________reflection will occur. less
WIthout a matching layer, what percentage of sound would be transmitted to the patient? 20%
What happens to the Q-factor if damping is increased? It decreases.
If you increase damping what happens to the pulse? It shortens the pulse.
To increase the range of frequencies found within the beam, you would increase or decrease damping? increase damping.
How are mechanical scan heads different than electronic scan heads? Mechanical heads have motors; electronic has no moving parts
Mechanical scan heads have what type of focus? Fixed
Mechanical scan heads have what type of frequency Fixed
How do you change the focus on a mechanical head? You have to change the the probe - head
To change the frequency on a mechanical head.... you have to chance the scan head
What does "array" mean? Multiple elements
What affect does focusing have on the resolution on a mechanical single-disc element transducer? improves the resolution
In what transducer are the scan lines perpendicular to the transducer? Linear Array transducer
In a linear array transducer, how is the beam steered? It isn't. There is no steering with a linear array.
In what transducers are crystals fired in groups of elements? Linear Sequential Array
In what transducer do scan lines NOT have a common origin? Linear Sequential Array
What shape does a linear sequential array produce? A rectangle
Produces a curvilinear image; fires in groups of elements; does NOT have a common point of origin curved sequential array
What type of transducer do I use everytime? Curved sequential array
Sector image with wide near field of view Curved sequential array
What transducer has a rectangular shape but produces a sector shaped image? Phased array transducer
elements arranged in a straight line, smaller footprint phased array
Electronic focusing and steering in a linear phased array. phasing
In phased arrays, the focusing and steering is controlled by delaying the electronic impulses to the element, and is controlled by what? The machine? The sonographer? The thickness of the element? The sonographer
Changing the timing difference between elements Phasing - electronically transmitted waves in different directions without the use of moving parts. Patterns are arranges similar to a windshield wiper.
Phasing steers the scan lines to produce a ________image. sector
A transducer that steers and focuses with phasing phased array
Arrays with no common point of origin vector arrays
what shaped does a vector array have? flat top
to send pulses out rapidly and repeatedly to create a frame of ultrasound Electronic beam steering
By delaying/timing the electrical impulses that control the elements, the beam can be steered Electronic beam steering
By delay/timing the electrical impulses that control the elements, the beam can be steered as well as focused
How do you tell if a beam is focused? The presence of a curvature of the pulsing
What type of array can be electronically focused, but mechanically steered? Annular array
What transducer has concentric circular elements cut from one slab of PZT? Annular Array
On what transducer do the rings independently focus? Annular array
What transducer focuses in both planes and transverse ? Annular array
What transducer has excellent lateral resolution? Annular array
Which transducer uses multiple circular elements? Annual array
Which of the following transducers has electronic focusing? All of the following do: Linear sequential, curvilinear, phased array and annular array
Which transducers have electronic steering? Linear sequential, curvilinear sequntial, and Phased array.
The bigger the impedence mismatch, the ____________the reflection. stronger. There is less transmission
Without a matching layer, what percentage of sound would be transmitted to the patient? 20%
What two characteristics of the active element are used to determine the frequency of sound created by a pulsed wave transducer? 1. The speed of sound in the PZT 2. The thickness of the element.
What is another name for a fixed focal depth in mechanical transducers? conventional, mechanical or fixed focusing
What are the two methods for fixed focusing? internal focusing - use of a curved active element or external focusing with the use of an acoustic lens.
Focusing occurss in what plane/planes? It occurs in both the vertical and horizontal planes because of the hour-glass shape of the beam.
What is an array comprised of? One piece of PZT cut into a collection of separate pieces called elements.
A wire connects each element to its own circuitry in the US system. What is the combination of the active element, wire and system electronics called? Channel
What are the types of array transducers? Linear, Annular and Convex
What is the arrangement of a linear array transducer? Active elements are arranged in a straight line.
What is the arrangement of a annular array transducer? Elements are arranged as circular rings with a common center.
What is the arrangement of a convex Array transducer? Elements are arranged in a bowed or arched line. The transducer may be called curvilinear, or curved.
Phased array always means... adjustable or multi-focus.
WHEN A SPIKE LINE IS STRAIGHT, IN A LINEAR PHASED TRANSDUCER....WHAT HAPPENS TO THE FOCUS? IT'S UNFOCUSED.
What changes the shape of the beam electronically? The beam former.
To focus a beam, the beam former uses a _____pattern . Curved pattern
Created by: jxw039
 

 



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