Transducers

Question 1

What is the piezoelectric effect?

Answer 1

heat is applied which causes crystals to vibrate and send sound wave to medium

Question 2

What is the most common piezoelectric material?

Answer 2

lead zirconate titanate (PZT)

Question 3

PZT is also called?

Answer 3

crystal, ceramic, active element

Question 4

What is polarization?

Answer 4

heating of PZT to Curie temperature to activate piezoelectric properties

Question 5

What is depolarization?

Answer 5

PZT is heated past Curie temperature and loses piezoelectric properties

Question 6

What is Curie temperarure?

Answer 6

365 degrees C

Question 7

Phased transducers can be?

Answer 7

steered electronically

Question 8

Vector transducers can?

Answer 8

angle the image; rectangle to trapezoid

Question 9

Which type of transducer contains multiple closely spaced crystals with an individual connection?

Answer 9

Array

Question 10

Which type of transducer has multiple crystals and electronic steering?

Answer 10

phased array

Question 11

Phased array transducers are always?

Answer 11

adjustable or multifocus

Question 12

Mechanical transducers are also called?

Answer 12

Liquid path, motorized, wobble, fixed focus

Question 13

A mechanical transducer contains how many elements?

Answer 13

1

Question 14

Image shape of a mechanical transducer

Answer 14

fan or sector shaped

Question 15

How is a mechanical transducer steered?

Answer 15

Mechanically; motor rotates single crystal

Question 16

Which type of transducer has a single fixed focus?

Answer 16

mechanical

Question 17

Mechanical transdcuers have _____ resolution in the far field

Answer 17

decreased

Question 18

If the element of a mechanical transducers is damaged, what will happen to the image?

Answer 18

completely lost; one crystal

Question 19

Which artifact is created with a mechanical transducers?

Answer 19

side lobes

Question 20

What is side lobe artifact?

Answer 20

hyperechoic lines appear to the side of anatomy in the far field

Question 21

What is used to correct side lobes?

Answer 21

Apodization

Question 22

How are the elements arranged in a linear array?

Answer 22

straight line

Question 23

How are the elements arranged in a convex array?

Answer 23

bowed or arched line (curved)

Question 24

Linear arrays are also called?

Answer 24

Linear switch array

Question 25

A linear array image has what shape?

Answer 25

rectangle

Question 26

A linear array has what type of steering?

Answer 26

electronic

Question 27

How are the elements energized in a linear sequential/switched array?

Answer 27

individually in a sequence

Question 28

How are the elements energized in a linear segmental array?

Answer 28

in groups

Question 29

If a crystal is damaged in an array, what will happen to the image?

Answer 29

single vertical dropoff

Question 30

Image shape of a curved array transducer

Answer 30

fan or sector

Question 31

Which is the only type of transducer that is both mechanical and electric?

Answer 31

annular phased array

Question 32

How are the elements of an annular phased array arranged?

Answer 32

concentric circles (onion)

Question 33

An annular phased array has what kind of steering?

Answer 33

mechanical

Question 34

If a crystal malfunctions in an annular phased array, what will happen to the image?

Answer 34

horizontal dropout

Question 35

What artifact is created by linear phased array?

Answer 35

grating lobes

Question 36

What corrects grating lobes?

Answer 36

apodization and subdicing

Question 37

What are grating lobes?

Answer 37

hyperechoic lines on the side of anatomy in the **near field**

Question 38

Vector arrays contain a combination of _____ steering and _______ focal zones

Answer 38

electronic; multiple