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Ultrasound Transducer
is a device which converts one form of energy to another.
Ultrasound Transducer
Converts electrical energy into sound (mechanical) energy, and vice versa.
Diagnostic Transducer
act as both a transmitter and receiver of UTZ
- Physical housing assembly
- Electrical connections
- Piezoelectric elements
- Backing materials
- Acoustic lens
- Impedance matching layer
Components And Construction Of A Typical Transducer
PHYSICAL HOUSING
This contains all the individual components.
PHYSICAL HOUSING
Provides the necessary structural support and acts as an electrical and acoustic (mechanical) insulator.
ELECTRICAL CONNECTIONS
Two __ are formed on the front and back face of the crystal by plating a thin film of gold or silver on these surfaces
thin film of gold or silver
Two electrical connections are formed on the front and back face of the crystal by plating a __ on these surfaces
Piezoelectric effect
was discovered by Jacques and Pierre Curie in 1880.
Curie Brothers (Jacques and Pierre)
Who discovered the piezoelectric effect?
PIEZOELECTRIC MATERIALS
Curie Brothers found that certain crystalline minerals when subjected to a mechanical force became electrically polarized which means that they generated voltages, vice versa.
Thinner
__ piezoelectric materials produce higher resonant frequencies.
QUALITY
The frequency also affects the __ of the ultrasound image
BETTER
The HIGHER the frequency, the __ the resolution
LESS
The LOWER the frequency, the __ the resolution
15 MHz
A __ transducer has very good resolution, but cannot penetrate very deep into the body
3 MHz
A __ transducer can penetrate deep in the body, but the resolution is not as good as the 15 MHz
BACKING MATERIALS
shortens the ultrasound pulse length which improves AXIAL RESOLUTION.
front face
BACKING MATERIALS: We are only interested in the vibrations that come off the __ of the transducer.
Backing or damping material
To try to eliminate the vibrations from the back face, and to control the length of vibrations from the front face, a __ is used
1. Araldite loaded with tungsten powder
2. Plastic
3. Cork
4. Rubber
5. Epoxy resin
Damping/ Backing material
ACOUSTIC LENS
The purpose: to improve image lateral resolution by reducing the beam width of the transducer.
LATERAL RESOLUTION
The width of the beam determines the __
LATERAL RESOLUTION
is the ability to resolve structures across or perpendicular to the beam axis.
1. Aluminium
2. Perspex
3. Polystyrene
Acoustic Lens materials
IMPEDANCE MATCHING LAYERS
is sandwich between the piezoelectric crystal and the patient.
IMPEDANCE MATCHING LAYERS
High-purity gamma alumina powder.
SPATIAL PULSE LENGTH
Length of a pulse from front to back.
SPL = length of each cycle times the number of cycles in the pulse.
SPATIAL PULSE LENGTH Formula
Shorter
__ pulse length improves resolution.
decreases
The spatial pulse length (SPL) usually __ with frequency
Lower
Higher SPL = _ Resolution
- Linear Array transducers
- Convex transducers
- Sector transducer
TYPES OF ELECTRONIC ARRAY TRANSDUCERS
LINEAR ARRAY TRANSDUCERS
Produces a parallel scan lines
LINEAR ARRAY TRANSDUCERS
Rectangular field of view.
LINEAR ARRAY TRANSDUCERS
The width of this image is approximately equal to the length of the transducer head.
LINEAR ARRAY TRANSDUCERS
Vascular (vessels), small parts and musculoskeletal applications.
LINEAR ARRAY TRANSDUCERS
Breast, scrotum and thyroid Utz
above 4MHz
LINEAR ARRAY TRANSDUCERS Operate at frequencies typically __.
CONVEX TRANSDUCERS
Convex in shape which provides a wide field of view which diverges with depth.
CONVEX TRANSDUCERS
Abdominal and obstetric scanning except echocardiography.
3.5 MHz
CONVEX TRANSDUCERS Operates at __
CONVEX TRANSDUCERS
best suited to image deep lying structures.
SECTOR TRANSDUCERS
Fan shaped, almost triangular.
SECTOR TRANSDUCERS
Used whenever there is only small space available.
SECTOR TRANSDUCERS
The small footprint and wide field of view
SECTOR TRANSDUCERS
Cardiac ultrasound, Cranial ultrasound, Gynaecological (TVS transducer)
ACOUSTIC COUPLING AGENT
Purpose : "To prevent air between the transducer and the skin of the patient"
↓ REFLECTION = ↑ TRANSMISSION
↑ GEL = __ REFLECTION = __ TRANSMISSION
ACOUSTIC COUPLING AGENT
Often referred to as "gel"
ph 5-10
ACOUSTIC COUPLING AGENT ph
True
T/F Too much gel is far better than not enough!
1. Carbomer
2. EDTA (Edetic Acid)
3. Propylene glycol
4. Trolamine
5. Distilled water
ACOUSTIC COUPLING AGENT INGREDIENTS
CARBOMER
It is a white, fluffy, acidic.
CARBOMER
Hygroscopic powder with a slight characteristic odour
EDTA (EDETIC ACID)
A white crystalline powder, very slightly soluble in water.
EDTA (EDETIC ACID)
Soluble in solutions of alkali hydroxides.
PROPYLENE GLYCOL
A colourless, odourless, viscous hygroscopic liquid with a slight sweet taste.
TROLAMINE
A clear, colourless or slightly yellow, odourless, viscous hygroscopic liquid.
Carbomer = 10.0 g
EDTA = 0.25 g
Propylene Glycol = 75.0 g (72.4 ml)
Trolamine = 12.5 g (11.2 ml)
Distilled Water = Up to 500 g (500 ml)
ACOUSTIC COUPLING AGENT FORMULA
POWER OR OUTPUT CONTROL
This controls the strength of the voltage spike applied to the crystal at pulse emission.
↑ intensity
↑ power = __ intensity
↑ intensity = ↑ strength of echo = ↑ px utz dose
↑ power = __ intensity = __ strength of echo = __ px utz dose
POWER OR OUTPUT CONTROL
Gain
DEPTH / F.O.V CONTROL
Allows to increase or decrease the depth of the FOV on the monitor
↑ area of interest = ↑ visualization
↓ depth = __ area of interest = __ visualization
GAIN
Refers to the degree of amplification applied to all returning echo signals.
GAIN
Adjust the overall brightness of the image
TIME GAIN COMPENSATION (TGC)
Allows adjustment of brightness of a specific depth of the image
FOCAL ZONE
should always be placed at the depth of interest on the utz image in order to ensure the best Lateral resolution
ZOOM / RES
Allow magnification of the areas of the UTZ image displayed on the monitor
