Transducers Pg 62-87

Front 1

What is an ultrasound beam?

Back 1

The width of the pulse of sound as it travels away from the transducer

Front 2

What determines the lateral resolution?

Back 2

The width of the beam in the scan plane

Front 3

lateral resolution

Back 3

minimum separation of two objects that are side by side to the ultrasound beam (how low can the resolution be to still be able to differentiate two lateral interfaces

Front 4

is intensity uniform through out the US beam?

Back 4

no

Front 5

side lobes

Back 5

artifact coming off the side of the US beam

Front 6

near zone

Back 6

area from the element out to a distance of one nearzone length

Front 7

Near Zone is also called

Back 7

Fresnel Zone

Front 8

What determines the near zone length

Back 8

size and operating frequency of the element

Front 9

what is aperture

Back 9

when the near zone length increases with increasing frequency and element size

Front 10

what two zones does an ultrasound beam consist of?

Back 10

near zone and far zone

Front 11

If aperture increases, near-zone length __________

Back 11

increases

Front 12

if frequency increases,near zone length _________

Back 12

increases

Front 13

The region that lies beyond a distance of one near zone legnth is called the _______

Back 13

far zone

Front 14

Far zone is also known as

Back 14

Fraunhoffer zone

Front 15

the beam width ________ with increasing distance from the tx in the far zone

Back 15

increases

Front 16

how do you calculate the beam width at the end of near zone....

Back 16

it is to 1/2 the width of the TX element

Front 17

At double the near zone length the beam is equal to

Back 17

it is equal to the diameter of the tx element

Front 18

What are three ways to focus

Back 18

1. using a curved
2. lens
3. phasing

Front 19

what area of the beam can focusing occur

Back 19

the near zone

Front 20

do narrow beams create better or worse images

Back 20

better

Front 21

focal point

Back 21

location where the beam reached its minimum diameter

Front 22

focal depth

Back 22

distance from the tx face to the focus

Front 23

focal depth is also known as...

Back 23

focal length, near zone length

Front 24

Sound beams _______ in the near zone

Back 24

converge

Front 25

sound beams _______in the far zone

Back 25

diverge

Front 26

focal depth

Back 26

distance from tx to the focal point

Front 27

what determines the focal depth

Back 27

tx diameter
frequency

Front 28

beams with a shallow focus have...

Back 28

1. small diameter
2. low frequency

Front 29

beams with deep focus have ....

Back 29

1. large diameter
2. high frequency

Front 30

Huygen's principle

Back 30

explains the hourglass shape of an imaging tx souond beam

Front 31

What determines the (f) of sound created by a pulsed wave tx

Back 31

thickness and speed of sound in the ceramic

Front 32

what determines the focal length of a sound beam

Back 32

diameter of ceramic and frequency of sound

Front 33

what determines the spread of a sound beam in the far field

Back 33

diameter of ceremic and frequency of sound

Front 34

which of the following tx have the shallowest focus>
a. 4 MHz, 4mm crystal diameter
b. 6MHz, 4mm crystal diameter
c.4 MHz, 6 mm crystal diameter
d. 6 Mhz, 6mm crystal diamter

Back 34

a

Front 35

which has the shallowest focus?
a. lowest (f), largest crystal diameter
b. highest (f), largest crystal diameter
c. lowest (f), smallest crystal diameter
d. highest (f), smallest crystal diameter

Back 35

c

Front 36

resolution

Back 36

the ability to image accurately

Front 37

axial resolution

Back 37

the ability to distinquish two structures that are close to each other along the beams main axis

Front 38

Synonyms for axial resolution

Back 38

LARRD
longitudinal
axial
range
radial
depth

Front 39

shorter pulses provide better or worse LARRD resolution

Back 39

better

Front 40

failure to pass meconium due to absence of ganglion cells in myenteric/Auerbauch's plexus due to failure of neural crest cell migration?

bilious vomitting, associated with Down's syndrome, due to failure of recanalization?

non bilious projectile vomitting at 2 weeks old, due to hypertrophy of pylorus, epigastric olive mass, 1st born males?

progressive dysphagia due to LOSS of Auerbauch's plexus, bird beak on barium swallow?

Back 40

Hirschprung Disease
Duodenal Atresia
Congenital Pyloric Stenosis
Achalasia

Front 41

can LARRD resolution be changed by the sonographer

Back 41

no

Front 42

what is the equation for axial resolution

Back 42

axial resolution=spl/2

Front 43

lateral resolution

Back 43

the minimum distance that two structures are separated by (side to side) that produces two distinct echos

Front 44

where is lateral resolution best>

Back 44

at the focus because the sound beam is narrowest at that point

Front 45

the ability to distinguish two structures lying close together is called

Back 45

resolution

Front 46

the ability to distinguish two structures lying close together front to back or parallel to the sound beam is called

Back 46

axial
LARRD

Front 47

axial resolution is measured with units of

Back 47

distance

Front 48

the more cycles there are in a pulse, the ----------(greater, lesser, same) is the numerical value of the range resolution

Back 48

greater

Front 49

__________ (high, low) frequency tx generally have the best range resolution

Back 49

high

Front 50

linear array

Back 50

produces rectangular images composed of many vertical, parallel scan lines

Front 51

The nearer your aperture the ________(better, worse) your resolution

Back 51

better

Front 52

what type of image does a convex or curved array produce

Back 52

sector

Front 53

linear phased array

Back 53

applies voltages to to most or all elements but at a small time delay so the sound is sent out in a specific path

Front 54

if a linear phased array voltage is applied from R to L the beam would steer

Back 54

L

Front 55

the sharper the curve, the _______(deeper, shallower) the focus

Back 55

more shallow

Front 56

the shorter the delays (less curvature) the _______ (shallower, deeper)

Back 56

deeper

Front 57

are phased linear array focused or steered

Back 57

focused

Front 58

what determines the beam width at the focus

Back 58

aperture, focal length, wavelegnth

Front 59

grating lobes

Back 59

additional beams coming from arrays

Front 60

apodization

Back 60

listening time

Front 61

what are three types of resolution

Back 61

detail
axial
lateral

Front 62

with detail resolution _______(smaller or larger) is better

Back 62

smaller

Front 63

if frequency increases, detail resolution improves but penetration _______

Back 63

decreases

Front 64

what improves lateral resolution

Back 64

reducing the beam diameter

Front 65

in dx Us tx what type of resolution is usually better

Back 65

axial

Front 66

the dividing point btw the near and far zones is at a distance from the tranducer equal to the ______ _____

Back 66

near zone

Front 67

tx size is also called

Back 67

aperture

Front 68

near zone length increases with increasing source _____ and _______ from the source

Back 68

aperture and frequency

Front 69

in the near zone, beam width_____ as distance from the tx increases

Back 69

decreases

Front 70

if a 5-MHz tx with a near-zone lengthof 10 cm is increased in size the near zone length

Back 70

increases

Front 71

a two cycle pulse of 5 MHz us produces separate echoes from reflectors in soft tissue separated by 1 mm

Back 71

true (calculate axial resolution)