Td And Beams

Front 1

any device that converts one form of energy into another

Back 1

transducer

Front 2

who discovered the PZE?

Back 2

Pierre and Jacques Curie in 1880s

Front 3

when a _________ force is applied to certain materials, they create a __________

Back 3

mechanical

voltage

Front 4

when voltage is applied to these materials, they change _________ and ____________

Back 4

shape

vibrate

Front 5

Another name for Piezoelectric

Back 5

ferroelectric

Front 6

U/S transducers transfer sound energy into the body and receive sound energy back from the body...T/F

Back 6

True

Front 7

The conversion of electrical energy into sound energy is called

Back 7

Piezoelectric effect

Front 8

What in the U/S machine converts electrical energy into sound energy?

Back 8

crystal, active element

Front 9

How are active elements made to be piezoelectric?

Back 9

They are heated to a Curie point

Front 10

What is the main component of the U/S transducer?

Back 10

crystal

Front 11

How do transducer crystals lose their piezoelectric properties?

Back 11

If they are heated above the Curie point

Front 12

At Curie point, what happens to the transducer?

Back 12

the element becomes depolarized

Front 13

In the transducer, what is bonded to the back of the active element that limits "ringing" of the crystal?

Back 13

dampening element

Front 14

what component of the transducer shortens SPL and pulse duration?

Back 14

dampening layer or backing material

Front 15

T/F
Dampening material increases bandwidth.

Back 15

True

Front 16

Backing material increases the Q-factor? T/F

Back 16

False, it decreases

Front 17

Dampening material __________ the transducers sensitivity to reflected echoes.

Back 17

decreases

Front 18

What component of the transducer reduces reflections at the transducer/tissue interface?

Back 18

matching layer

Front 19

Another name for matching layer

Back 19

impedance matching layer

Front 20

matching layer is usually _____ the wavelength of the U/S beam

Back 20

1/4

Front 21

Reduces the impedance different between the transducer element and the skin

Back 21

matching layer

Front 22

helps send more U/S energy into the body rather than reflecting it

Back 22

matching layer

Front 23

helps matching layer to reduce the impedance difference

Back 23

gel

Front 24

What has the highest impendance range?

Back 24

PZT

Front 25

What has the lowest impedance range?

Back 25

skin

Front 26

The component of the transducer that sends and receives voltages

Back 26

wire

Front 27

The wire sends an electrical voltage to the transducer; this voltage __________ the crystal and causes it to ___________.

Back 27

deforms

vibrate

Front 28

The ______ receives an electrical voltage for processing into an image

Back 28

wire

Front 29

Plastic or metal housing surround the components of the transducer

Back 29

case

Front 30

The case prevents _______ from altering the transducer's performance

Back 30

noise

Front 31

Protects the transducer's parts

Back 31

case

Front 32

The case and insulation can protect the patient from _________________

Back 32

electrical shock

Front 33

The operating frequency of a transducer

Back 33

resonant frequency

Front 34

Another name for resonant frequency

Back 34

natural frequency

Front 35

Transducer frequency depends on the _________ of the crystal, and the __________ of sound in the crystal.

Back 35

thickness

speed

Front 36

Frequency and speed of sound are ___________ related.

Back 36

directly

Front 37

Frequency and crystal thickness are ___________ related.

Back 37

indirectly

Front 38

Higher the speed, the _________ the frequency

Back 38

higher

Front 39

Lower the speed, the __________ the frequency

Back 39

lower

Front 40

Thinner crystal, ________ frequency

Back 40

higher

Front 41

thicker crystal, ___________ frequency

Back 41

lower

Front 42

Pulsed U/S transducers emit a __________ of frequencies

Back 42

spectrum

Front 43

The difference between the highest and the lowest frequency in a pulse

Back 43

bandwidth

Front 44

The shorter the pulse, the _______ the bandwidth.

Back 44

wider

Front 45

_________ pulse duration, wide bandwidth.

Back 45

short

Front 46

_________ pulse duration, narrow bandwidth.

Back 46

long

Front 47

Resonant frequency is at the _______ of the bandwidth.

Back 47

center

Front 48

Advantages of wide bandwidth

Back 48

fewer cycles per pulse gives longer listening time

wider bandwidth can receive a wider range of frequencies

Front 49

Disadvantage of wide bandwidth

Back 49

decreased probe sensitivity
element is not as responsive to the returning sound waves (pressure)

Front 50

Shorter pulses need ________ amplitude signals to vibrate the transducer and make the PZE happen

Back 50

bigger