UTZ P2

To convert electrical energy into mechanical energy and vice versa

What is the primary function of a plezoelectric crystal in an ultrasound transducer?

Lead zirconate-titanate (PŹT)

The material that is commonly used in piezoelectric crystals due to its high sensitivity

To absorb ultrasound waves and reduce crystal ringing

What is the purpose of the damping material in an ultrasound transducer?

Phased array probe

An ultrasound probe that is best suited for cardiac imaging

To elimninate air gaps and improve sound transmission

The primary advantage of using a coupling medium (gel) in ultrasound imaging

B-mode

A mode displays a two-dimensional grayscale image of anatomical structures

Spatial Pulse Length

It determines axial resolution in ultrasound imaging

Appears black with no internal echoes

a characteristic of an anechoic structure

To reduce acoustic impedance mismatch between the crystal and tissue

The function of matching layer in transducer

Endocavitary probe

A probe that is typically used for endovaginal examinations

Piezoelectric

The principle where mechanical pressure generates electrical charges in certain crystals.

Matching Layer

The layer in a transducer that reduces acoustic impedance mismatch between the crystal and skin.

A-mode

The mode that displays amplitude spikes representing echo depth and intensity.

Coupling medium

A gel applied to the skin to eliminate air gaps during ultrasound.

Lateral Resolution

The resolution determined by beam width, affecting the ability to distinguish side-by-side objects.

Positive & negative charges called dipoles

What charges are found in piezoelectric crystals?

Randomly arranged

How are dipoles arranged in their normal state?

Dipoles align

What happens when the material is heated above a certain temperature?

The crystal expands

What occurs when the piezoelectric crystal is stimulated electrically?

The crystal contracts

What happens when the polarity of the crystal is reversed?

Converts an electric signal into mechanical motion that produces ultrasound.

What does the sequence of expansion and contraction achieve?

Piezoelectric crystal

What is considered the “heart” of the ultrasound transducer?

Quartz, Lithium niobate, Lithium sulfate.

Give examples of crystalline piezoelectric materials.

Barium titanate, Lead metaniobate.
BTLM

Name other ceramic piezoelectric materials.

It is measured in meters per volt and indicates the ultrasound transmitting capacity.

What is “strain” in relation to ultrasound transducers?

What does the generated electric field determine in a piezoelectric crystal?

The stress-induced signal and the capacity of crystals used as an ultrasound receiver.

electromechanical coupling factor

It indicates the efficiency of energy conversion from electrical to mechanical.

Thickness

The critical dimension of a piezoelectric crystal

Thinner elements operate at higher frequencies.

How does crystal thickness relate to frequency?

One-half wavelenght

For a single wave to move back & forth in the crystal, what should the distance (thickness) be?

When the crystal thickness equals one-half the wavelength of ultrasound.

When does maximum energy transfer between mechanical and electric states occur?

0.3 mm

A 2.5 MHz transducer produces ultrasound with a wavelength of 0.6 mm. What is the most effective crystal thickness?

0.2 to 2 mm

the typical thickness of transducer elements

The property of the crystal is destroyed by altering the alignment of dipoles.

What happens if the crystal is heated above 350°C?

A combination of epoxy resin and tungsten powder.

What materials make up the damping material in ultrasound transducers?

Dumpling Material

It absorbs ultrasound by terminating the ringing of the crystal.

It reduces sensitivity because it lowers the intensity of the output signal.

How does damping material affect transducer sensitivity?

Matching Layer

It provides an acoustic impedance between the piezoelectric crystal and soft tissue.

It allows more of the ultrasound beam to be reflected back to the transducer.

How does the matching layer improve ultrasound transmission?

An epoxy resin–tungsten powder matrix designed to reduce reflection at the crystal’s surface.

What material is the matching layer typically made of?

The majority of the ultrasound is reflected.

What happens when ultrasound passes through two very different materials?

To prevent reflection between air and skin, allowing ultrasound waves to enter the body.

Why is gel necessary in ultrasound imaging?

It ensures similar acoustic impedances so the wave can pass effectively through the body.

What is the role of impedance matching in ultrasound?

Because air has very low impedance, even a thin layer reflects almost all sound.

Why does air prevent ultrasound penetration into tissue?

Both facilitate the passage of ultrasound across the transducer–skin boundary.

What do matching layers and coupling media have in common?

To prevent air between the transducer and the patient’s skin.

The main purpose of an acoustic coupling agent

Increased gel → decreased reflection → increased transmission.

How does increasing gel affect ultrasound transmission?

Ph 5-10

The typical pH range of an acoustic coupling agent

Carbomer, EDTA (Edetic Acid), Propylene glycol, Trolamine, Distilled water.

Name the common ingredients of an acoustic coupling agent

Carbomer

Fluffy white acidic powder that allows other ingredients in product to work

Carbomer

Hygroscopic powder with a slight characteristic odor

EDTA (Edetic Acid)

White crystalline powder, very slightly soluble in water

EDTA (edetic acid)

Soluble in solutions of alkali hydroxides

Propylene Glycol

A colorless, odorless, viscous hygroscopic liquid with a slight sweet taste

Trolamine

A clear, colorless or slightly yellow, odorless, viscous hygroscopic liquid

Detail

Ability of images to reproduce small objects

Definition

Refers to reproducing larger objects that have little tissue differentiation

Distortion

Results from the unequal magnification of anatomicak objects that lie different distancws from the image receptor

Spatial Resolution

It measures the ability of an imaging system to reproduce very small high contrast objects

Contrast Resolution

The ability to differentiate anatomic structures having similar tissue

Noise

The variation in signal level contributed by noise causes brightness fluctuations in the image

Axial Resolution

The ability to image closely spaced interferaces along the axis of the ultrasound beam

Millimeters

Unit of axial resolution

Lateral Resolution

The ability to image closely spaced interfaces perpendicular to the axis of ultrasound beam

Beam

It refers to the width of a pulse as it travels away from the transducer

Ultrasound transducer

a device that produces sound waves that bounce off body tissues and make echoes

Generated Electric Field

It determines the stress induced signal and capacity of crystals used ultrasound receiver

Endocavitary probe

This probe provides the opportunity to perform internal examinations of the patient.Therefore, they are designed to fit specific body orifices.

Pencil probe

This probe used to measure blood flow and the speed of sound in blood.