UTZ p2 ppt 2

Ultrasound transducer

also called a probe, is a device that produces sound waves that bounce off body tissues and mak e c h o e s .

Case, crystal, damping material, matching layer

Components of single element transducer:

Crystal

heart of transducer is the piezoelectric crystal or transducer element

• Quartz, Lithium niobate, Lithium sulfate

What are the crystalline materials?

Lead zirconate

material of choice because of higher sensitivity and superior efficiency

Lead zirconate, barium titanate, lead metianobate

What are the ceramic materials?

Strain

Measures in meters per volt

• An indication of UTZ transmitting capacit

Generated electrical field

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

Electromagnetical coupling factor

indicates the efficiency of energy conversion from electrical to mechanical

thickness

• The critical dimension of piezoelectric crystal is

One half wavelength

In order to have a single wave move back & forth between the front and back of crystal, the distance from one surface to the next should be

Thickness is one half the wavelength of UTZ

• Maximum energy transfer between the mechanical & electric state occurs when

350 celcius

Heat in excess of _ will destroy the property of crystal by altering the alignment of dipole

Damping material

• Combination of epoxy resin and tungsten powder

• Absorbs UTZ emitted by terminating the ringing of crystal

Matching layer

• A layer of material with an acoustic impedance between that of piezoelectric crystal and soft tiss

Coupling medium

• Impedance Matching/Gel

Carbomer

Fluffy white acidic powder that allows other ingredients in the products to work

• Hygroscopic powder with a slight characteristic odour

Edta ( edetic acid )

• White crystalline powder, very slightly soluble in water

• Soluble in solutions of alkali hydroxides

Propylene glycol

A colourless, odourless, viscous hygroscopic liquid with a slight sweet taste

Trolamime

• A clear, colourless or slightly yellow, odourless, viscous hygroscopic liquid

Axial resolution

is the ability to image closely spaced interfaces on the axis of the ultrasound beam

Spatial pulse length

axial resolution depends primarily on the length of the ultrasound pulse in space

Lateral resolution

•- is the ability to image closely spaced interfaces perpendicular to the axis of the ultrasound beam

Beam Width

• Lateral resolution is approx. equal to the effective beam width

• Decreasing the beam width improves the lateral resolution by allowing objects close together

Beam

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

Near zone, near field or Fresnel zone

region extending from the element to a distance of one near-zone length

• Far zone, far field or Fraunhofer zone

region that lies beyond the distance of one near zone length

Linear probe

t h e piezoelectric crystal arrangement is linear, t h e shape of t h e b e a m is rectangular, a n d t h e near-field resolution is good.

Transesophagealexaminations

A b d o m i n a l e x a m i n a t i o n s

B r a i n e x a m i n a t i o n

What can you use t h e phased array

t r a n s d u c e r f o r ?