Chapter 10

Question 1

_ is the ability to create

accurate images.

Answer 1

Resolution

Question 2

_ measures the ability of a 
system to display two structures that are 
very close together when the structures 
are parallel to the sound beam’s 
main axis. (one in front of the other)

Answer 2

Axial resolution

Question 3

_ answers the question: What is the minimum distance that two
structures positioned front-to-back can be
apart and still produce two distinct echoes on
an ultrasound image?

Answer 3

Axial resolution

Question 4

Axial resolution is usually measured in

Answer 4

units of distance such as mm

Question 5

Axial resolution is related to

Answer 5

SPL and pulse duration

Question 6

_ pulse improve axial resolution

Answer 6

Shorter

Question 7

Is axial resolution adjustable? Why/why not?

Answer 7

No, SPL for a transducer is fixed, you cannot change the axial resolution.

Question 8

Typical value for axial resolution

Answer 8

0. 1-1mm (for class)

0. 05-0.5mm (for SPI)

Question 9

For axial resolution, _ numerical values indicated shorter pulses and _ image accuracy

Answer 9

Lower

Improve

Question 10

Axial resolution AKA

Answer 10

LARRD
Longitudinal
Axial
Range
Radial
Depth

Question 11

Image quality is better when axial

resolution has a _ numerical value.

Answer 11

Lower

Question 12

The mathematical description of axial

resolution is:

Answer 12

Axial resolution= SPL/2

Axial resolution= wavelength x # of cycles in pulse/2

Question 13

Axial resolution is determined by

Answer 13

Pulse length

Question 14

_ pulses yield improved axial resolution

Answer 14

Shorter

Question 15

A short pulse is created in 2 ways:

Answer 15

1. Less ringing

2. Higher frequency

Question 16

A pulse is _ if there are few cycles in the

pulse.

Answer 16

Short

Question 17

Crystal dampening creates shorter pulses by

Answer 17

reducing the ringing of the crystal after it has

been excited by an electrical signal.

Question 18

A pulse is _ if each cycle in the pulse has a short

wavelength.

Answer 18

Short

Question 19

Shorter wavelengths are characteristic of

Answer 19

Higher frequency sound

Question 20

Pulses made of _ frequency cycles have better axial resolution

Answer 20

Higher

Question 21

Better axial resolution is associated with:

Answer 21

Shorter SPL
Shorter pulse duration
Higher frequencies (shorter wavelength)
Fewer cycles per pulse (less ringing)
lower numerical values

Question 22

Which is the best and worst axial resolution:
A. 12 MHz; 6 cycles/pulse
B. 12 MHz; 3 cycles/pulse
C. 4 MHz; 8 cycles/pulse
D. 4 MHz; 2 cycles/pulse

Answer 22

Best: B
Worst: C

Question 23

The ability to distinctly identify two 
structures that are very close together 
when they are side by side, or 
perpendicular, to the sound beam’s 
main axis.

Answer 23

Lateral resolution

Question 24

_ resolution answers the question:
◦ What is the minimum distance that two structures
positioned side-by-side can be apart and still produce
two distinct echoes on an ultrasound image?

Answer 24

Lateral

Question 25

Lateral resolution is measured in units of

Answer 25

Distance | mm, cm

Question 26

Lateral resolution: _ numbers are preferable since they | indicate more accurate images

Answer 26

Smaller

Question 27

Lateral resolution is determined by

Answer 27

The width of the sound beam

Question 28

_ beams have better lateral resolution

Answer 28

Narrow

Question 29

Beam diameter varies with _; lateral resolution varies with

Answer 29

Depth | Depth

Question 30

Lateral resolution AKA

Answer 30

``` LATABP Lateral Angular Transverse Azimuthal Beam width variation Point spread artifact ```

Question 31

Lateral Resolution is best at

Answer 31

the focus | where the beam is the narrowest.

Question 32

Lateral resolution=

Answer 32

beam diameter

Question 33

When two side-by-side reflectors are closer to each other than the width of the beam, _ reflection is observed on the image

Answer 33

only one

Question 34

Lateral resolution is degraded/worse in

Answer 34

the far field