Ultrasound Physics Review 2

Front 1

What determines the frequency of the transducer

Back 1

The thickness of the transducers element and the propagation speed of the transducer material

Front 2

You are performing an ultrasound exam with a wide bandwith transducer. What is the advantage you obtain with this transducer compared to a narrow bandwith transducer?

Back 2

Improved Axial resolution

Front 3

Which of the following can best improve lateral resolution: Increase damping, Decreased frequency, Increased bandwith, Use of a curved crystal, or Decreased aperature?

Back 3

Use of a curved crystal

Front 4

What is the location where the sound beam reaches its narrowest diameter known as?

Back 4

Focal Zone

Front 5

You are using a type of focusing that varies the number of cycles being fired in a segment, what is this called?

Back 5

Aperature focusing

Front 6

Which type of transducer produces a sector image shape?

Back 6

Phased and Annular array

Front 7

What is the term for a transducer that an array of rectangular elements are arranged in a straight line?

Back 7

Linear Array

Front 8

For linear array transducer, which method of focusing is used to focus the beam in the elevational direction?

Back 8

Mechanical focusing

Front 9

What transducer produces a beam that is symmetrical about the beam axis?

Back 9

Annular array

Front 10

A transducer with a small foot print has which of the following disadvantages: Its too large to use for intercostals scanning, The far field of view is only 1/4 the diameter of the transducer, The Q value is very high, or Focusing degrades at a depth of twice the transducer aperature

Back 10

Focusing degrades at a depth of twice the transducer aperature

Front 11

Which of the folllowing will not improve axial resolution: Increased Damping, Increased Transducer frequency, Increased bandwith, decreased pulse length, or Increased focusing

Back 11

Increased focusing improves lateral resolution

Front 12

You are reviewing an ultrasound image that has a sector display format with a pointed top. What kind of transducer produced this image?

Back 12

Phased array

Front 13

Where is the point of maximum intensity in a sound beam called?

Back 13

Focal point

Front 14

Constructive and destructive interference of sound waves from each individual sound source of a transducer is known as what?

Back 14

Huygens principle

Front 15

Increasing the transducer diameter has which of the following effects: Increased near zone length, Increases the frequency, Increases the beam diameter in the far field?

Back 15

Increases the near zone length

Front 16

A linear array transducer with 4 transmit focal sones selected requires how many pulses on each vector to create the image?

Back 16

4

Front 17

If you wish to adjust the focusing characteristics while scanning with a curved linear array, what type of focusing are you manipulating?

Back 17

Multizone transmit

Front 18

Which of the following transducers is electronically focused but mechanically steered: Segmental linear array, Switched linear array, Phased linear array, Single element mechanical sector, or Annular array?

Back 18

Annular array

Front 19

What type of transducer has the same measurement for elevational and lateral resolution?

Back 19

Annular array

Front 20

You are using a linear array transducer to image a thyroid mass and would like to use a transducer in which the thinnest slice is close to the depth of the mass. Where is the thinnest width of the sound beam in the out-of-plane dimension?

Back 20

It is at the point of mechanical focusing

Front 21

If you wish to produce a sonogram in a rectangular format, what transducer should you choose?

Back 21

Linear array

Front 22

What is another name for axial resolution?

Back 22

Range (L.A.R.R.D Longitudinal axial range radial depth)

Front 23

Dynamic apodization is a method employed to do what?

Back 23

Reduce side lobes

Front 24

If you measure the width on a standard one dimensional linear array transducer, which measure of resolution would be the worst: Axial, Lateral, Elevational, Contrast, or Temporal?

Back 24

Elevational

Front 25

What should you do to obtain the best lateral resolution for a given transducer?

Back 25

Use the maximum number of transmit focal zones

Front 26

You have detected a small hyperechoic focus within the gallbladder. There is no distal acoustic shadow. What can you do to aid visualization of the shadow?

Back 26

Increase the transducer frequency

Front 27

You are scanning a phantom containing many small spherical cystic structures imbedded in a tissue mimmicking material, what type of resolution is best evaluated with this phantom?

Back 27

Elevational

Front 28

Which statement is not true regarding lateral resolution: It is equal to beam width, It is improved by focusing, It is defined as the minimum separation required to resolve two structures perpendicular to the beam axis, It is also known as the azimuthal resolution, or It remains constant throughout scanning depth

Back 28

It remains constant throughout scanning depth

Front 29

Which type of transducer will decrease the slice of thickness of the beam?

Back 29

A linear array with multiple rows of elements

Front 30

What is the algebraic sumnation of waves called?

Back 30

Interference

Front 31

What is the matching layer between the piezoelectric element and the tissue designed to do?

Back 31

Reduce the acoustic impedance mismatch between the element and tissue

Front 32

What does dynamic receive focusing use?

Back 32

Delay lines after the echoes are detected in the array elements

Front 33

What transducer factor characterizes the frequency bandwith of the transmitted ultrasound wave?

Back 33

The Q-Value

Front 34

Varying the excitation voltage to each crystal in the group used to form the ultrasound pule is called what?

Back 34

Apodization

Front 35

Describe a phased array transducer.

Back 35

Electronically focused along the length os the array mechanically focused along the width, and electronically steered

Front 36

Resolution of the two structures parallel to the path of the sound beam is termed what?

Back 36

Axial resolution

Front 37

Which transducer has the same line density in both the near and far fields?

Back 37

Linear array

Front 38

Which of the following technical features minimizes the degree to which beam width varies with depth: Apodization, Dynamic aperature, Copredessing, Rectification, Frame averaging

Back 38

Dynamic Aperature

Front 39

The sound beam can be focused by all of the following except which: Acoustic mirror, Acoustic lens, Curved crystal, Matching layer, or Electronic phasing?

Back 39

Matching layer

Front 40

What type of focusing decreases the frame rate?

Back 40

Multiple transmit focusing

Front 41

For a single thansducer to offer multiple frequency scanning selections it must have what?

Back 41

Wide bandwith

Front 42

The ability to distinguish between adjacent structures that produce echoes of similar amplitude is termed what?

Back 42

Contrast resolution

Front 43

Increasing scan line density will improve what?

Back 43

Lateral resolution

Front 44

The conversion of an incident pressure wave to an electrical signal is what?

Back 44

The piezoelectric effect

Front 45

Electronic focusing in the transmit mode is accomplished how?

Back 45

Time delays to excite crystal elements

Front 46

What is the purpose of subdicing?

Back 46

To reduce grating lobes

Front 47

What transducer component is designed to control piezoelectric element ringing?

Back 47

Backing material

Front 48

The transducer you are using is an array assembly. What is an advantage of this type of transducer?

Back 48

Transducer arrays enable electronic focusing and steering

Front 49

Which of the following is not associated with a low Q transducer: wide bandwith, multifrequency selection, long pulse length, diagnostic pulsed waved ultrasound, loss of most energy in first few vibrations?

Back 49

Long pulse length

Front 50

An internal method of focusing is what?

Back 50

Curved piezoelectric element

Front 51

If the number of cycles in the transmitted pulsed wave is increased what will be degraded?

Back 51

Axial resolution

Front 52

You have been requested to image a superficial mass and to adjust your equipment to maximize spatial resolution. Spatial resolution consists of what?

Back 52

Lateral and Axial resolution

Front 53

What is the purpose of the radiofrequency shield that is placed around the crystal and backing material of the ultrasound probe?

Back 53

It reduces electromagnetic interference

Front 54

An electronic method of reducing transducer ringing and improving axial resolution is termed what?

Back 54

Dynamic damping

Front 55

What type of resolution is affected most by pulse duration?

Back 55

Axial resolution

Front 56

With a standard one dimensional linear array transducer what type of resolution is affected most by aperature size?

Back 56

Elevational resolution

Front 57

The spectrum of frequencies emitted by a pulsed wave transducer is known as what?

Back 57

Bandwith

Front 58

What is the optimal thickness for the matching layer?

Back 58

one fourth of a wavelength

Front 59

What is a method used to improve frame rates with multizone electronic focusing termed?

Back 59

Aperature focusing

Front 60

If you want to use an array transducer that allows you to control transmit focal depth, what type would you select?

Back 60

Linear array, Convex array, Phased array, Annualar array

Front 61

If you want to perform an abdominal sonogram with the largest possible field of view in both the near field and depth, what type of transducer would be most preferable?

Back 61

Convex array

Front 62

You are using a linear array transducer to evaluate the thyroid gland, for standard B mode imaging, this modern day transducer most likely produces pulses of how many cycles?

Back 62

One to three

Front 63

What is the purpose of applying multiple matching layers to the transducer face?

Back 63

Each matching layer thickness is optimized for a different frequency of the transmitted bandwith which improves sound transmission at the element-tissue interface

Front 64

For nonfocused transducer, the region between the transducer element and the point at which the sound beam is narrowest is called what?

Back 64

Near zone distance

Front 65

What is the minimum beam diameter for an unfocused disk transducer?

Back 65

1/2x disk diameter

Front 66

You must obtain intercostals views to image a liver mass on a small elderly woman, but the large probe you are using does not provide sufficient contact. What probe would be most helpful in this situation?

Back 66

Phased array

Front 67

You have been asked to perform an endovaginal examination of a patient postmenopausal bleeding to evaluate the endometrial thickness. What is the main advantage of scanning endovaginally compared to scanning with a conventional curved linear array through the pelvis?

Back 67

Since the endovaginal probe is closer to the area of interest, a higher frequency transducer can be used, resulting in superior spatial resolution

Front 68

What defines the best axial resolution that can be obtained with a given transducer?

Back 68

Spatial pulse lenght / 2

Front 69

The ultrasound system in your lab has multiple transducers that exhibit different axial resolution for the following axial resolution measurement, which offers the finest detail: .77, .44, .31, .20, or .15mm

Back 69

.15mm

Front 70

What term describes the ability of sound to separate closely spaced objects?

Back 70

Resolution

Front 71

What happens when pressure is applied to a piezoelectric crystal?

Back 71

It emits an electrical signal

Front 72

How is beam focused with a single element transducer?

Back 72

With a curved element

Front 73

What arrary transducer fires all of the elements at once with very small time differences to create the beam?

Back 73

Linear segmental array, Convex array, Annular array, Linear sequential array, and phased array

Front 74

Increasing the following parameter will improve axial resolution: Pulse duration, Pulse length, Frequency, Period, or Focusing?

Back 74

Frequency

Front 75

Which represents the best measure of resolution for modern day ultrasound scanner: Contrast, Axial, Elevation, Temporal, or Lateral?

Back 75

Axial

Front 76

Which of the following transducers produces side lobes: Mechanical sector, Linear sequential array, Phased array, Convex array or all

Back 76

All of them

Front 77

You are scanning the abdomen of an average sized 8yr old with a 3.5MHz Convex array probe. What comprimise are you making by selecting this probe?

Back 77

Decreased spatial resolution

Front 78

Which type of transducer is best suited for small parts imaging?

Back 78

Linear array

Front 79

Which of the following transducer types is best suited for cardiac imaging: Mechanical, Linear, Phased, Convex, or Annular

Back 79

Phased array

Front 80

Which of the following can not be evaluated with a tissue equvalent phantom: Axial resolution, Lateral resolution, Contrast resolution, Slice thickness, Temporal resolution

Back 80

Temporal resolution