chapter 8 Flashcards

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1
Q

Transducer

A

is any device that converts one form of energy into another

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2
Q

what are the two functions of transducers

A

during transmission electrical energy from the system is converted into sound
during reception the reflected sound pulse is converted into electricity

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3
Q

Piezoelectric Effect

A

property of certain material to create a voltage when they are mechanically deformed or when pressure is applied to them

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4
Q

Reverse piezoelectric effect

A

piezo. material change shape when a voltage is applied to them

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5
Q

Piezoelectric or ferroelectric

A

material which convert sound into electricity

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6
Q

what are the peieozelectric material used in clinical transducers

A

lead, zirconate, titanate, or PZT

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7
Q

what are the synonyms of PZT

A

ceramic, active element, or crystal

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8
Q

What is the case of a transducer?

A

cylindrical tube, it protects the internal components of the transducer from damage. Insulates the patient from electrical shock

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9
Q

What is the electrical Sheild of a transducer?

A

Metallic barrier lining the inside of the case. prevents spurious electrical signals in the air. Helps prevent electrical noise from contaminating the clinically I,portant electrical signals used to create diagnostic images

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10
Q

Acoustic insulator

A

a thin barrier of cork or rubber that isolates or uncouples the internal components of the transducer from the case. Prevents vibrations in the case from inducing an electrical voltage in the PZT of the transducer

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11
Q

PZT or active element

A

The crystal. emitted by the transducer are related to the dimensions of the active element. is 1 half wavelength thick

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12
Q

wire

A

provides electrical connection between the PZT and the ultrasound system. the crystals vibrate produces a voltage that must return to the system for processing into an image

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13
Q

Matching layer

A

increasing the efficiency of sound energy transfer between the active element and the body
protects the active element
the matching layer is 1 half wavelength thick

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14
Q

Backing material

A

reduces the ringing of the PZT

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15
Q

another name for backing material

A

damping element

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16
Q

what are the characteristics of damping material

A

high degree of sound absorption
acoustic impedance similar to PZT

17
Q

what are the three consequences of using backing material

A

decreased sensitivity
wide bandwidth
low quality factor

18
Q

decreased sensitivity

A

during reception, transducer with damping material are less able to convert low-level sound reflections into meaningful electrical signals

19
Q

bandwidth

A

is the range of frequencies in the pulse

20
Q

wide bandwidth or broadband

A

imaging probes produce pulses

21
Q

long duration events are narrow bandwidth, whereas

A

short duration events are wide bandwidth (broadband)

22
Q

Quality factor

A

unites number that is inversely related to bandwidth

23
Q

the temperature at which PZT is polarized

A

Curie temperature or Curie point

24
Q

Depolarization

A

the loss of piezoelectric properties