oct 17

Question 1

converts one form of energy to another

Answer 1

transducer

Question 2

convert electric energy into ultrasound energy, and vice versa

Answer 2

ultrasound transducers

Question 3

to press

Answer 3

piezo

Question 4

electron, organic plant resin that was used in early studies of electricity

Answer 4

amber

Question 5

results in the production of a pressure when an applied voltage deforms these materials.

Answer 5

piezoelectricity

Question 6

used commonly as materials in the production of modern ultrasound transducer elements

Answer 6

lead zirconate titanate

Question 7

ceramics often are combined with a nonpiezoelectric polymer to create materials called

Answer 7

piezo-composite

Question 8

take the form of disks.

Answer 8

single-element transducers

Question 9

contain numerous elements that have a rectanguar shape

Answer 9

linear array transducers

Question 10

refers to the piece of piezoelectric material that converts electricity to ultrasound, and vice versa

Answer 10

transducer element aka piezoelectric element

Question 11

Elements, with their associated case and damping and matching materials, are called

Answer 11

transducer assembly
probe
scan head
or
transducer

Question 12

produces a two- or three-cycle ultrasound pulse

Answer 12

single-cycle driving voltage

Question 13

typically 5 to 30 cycles, are used for Doppler techniques

Answer 13

loner-driving voltages

Question 14

preferred, or natural, frequency of operation for the element

Answer 14

operating frequency (sometimes called resonance frequency)

Question 15

Operating frequency is determined by the following:

Answer 15

• The propagation speed of the element material (ct).
• The thickness (th) of the transducer element

Question 16

Typical diagnostic ultrasound elements are ___mm thick and have propagation speeds of ___ mm/μs

Answer 16

0.2 to 1 mm, 4 to 6 mm/μs

Question 17

higher frequency

Answer 17

better detail resolution

Question 18

lower frequency

Answer 18

degradation in resolution

Question 19

quicker, more convenient, and more cost-effective than changing of transducers

Answer 19

push-button frequency switching

Question 20

in which echoes of twice the frequency sent into the body are received to improve the image.

Answer 20

harmonic imaging

Question 21

mixture of metal powder and a plastic or epoxy resin, is attached to the rear face of the transducer elements to reduce the number of cycles in each pulse

Answer 21

Damping (also called backing) material

Question 22

equal to period multiplied by number of cycles in the pulse

Answer 22

pulse duration

Question 23

reduces pulse duration and spatial pulse length and improves resolution

Answer 23

damping

Question 24

• reduces the time that the bell rings after the tap
• also reduces the loudness of the ringing

Answer 24

rubber

Question 25

reduces the ultrasound amplitude and thus decreases the efficiency and sensitivity (ability to detect weak echoes) of the system (an undesired effect)

Answer 25

damping material

Question 26

composites and damping material ___ pulses and ____ resolution

Answer 26

shorten, improve

Question 27

facilitate the passage of ultrasound across the transducer-skin boundary

Answer 27

matching layer and coupling media

Question 28

applied to the skin before transducer contact. This eliminates the air layer and facilitates the passage of sound into and out of the tissue

Answer 28

coupling medium

Question 29

- designed to enter the body via the vagina, rectum, esophagus, or a blood vessel (catheter mounted type) - allow the transducer to be placed closer to the anatomy of interest, thus avoiding intervening tissues and reducing the sound transmission path length

Answer 29

invasive transducers

Question 30

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

Answer 30

beam

Question 31

The width in the scan plane determines the ____, whereas the width perpendicular to the scan plane determines the extent of the section thickness artifact.

Answer 31

lateral resolution

Question 32

- additional beams - source of artifacts

Answer 32

side lobes

Question 33

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

Answer 33

near zone, near field, or Fresnel zone

Question 34

- determined by the size and operating frequency of the element

Answer 34

Near-zone length (NZL; also called nearfield length)

Question 35

Near-zone length increases with increasing frequency or element size, which is also called

Answer 35

aperture

Question 36

The region that lies beyond a distance of one near-zone length is called

Answer 36

far zone, far field, Fraunhofer zone

Question 37

What is somewhat surprising but true is that even in the case of this flat, unfocused transducer element, there is some beam narrowing. This narrowing is sometimes called

Answer 37

natural focus

Question 38

size of a source of ultrasound

Answer 38

aperture

Question 39

distance from the transducer to the center of the focal region

Answer 39

focal length

Question 40

distance between equal beam widths that are some multiple (e.g., ×2) of the minimum value (at the focus)

Answer 40

focal zonelength aka depth of field in photography

Question 41

wave length decreases, frequency ____

Answer 41

increases

Question 42

thinner elements yield? higher or lower frequency

Answer 42

higher

Question 43

pulse duration is equal to

Answer 43

period multiplied by number of cycles in the pulse

Question 44

increase in frequency or in aperture ______ the near-zone length

Answer 44

increases

Question 45

At a sufficient distance from the transducer, an increase in frequency or transducer size can _____ the beam diameter

Answer 45

decrease