Axial And Lateral Resolution

Question 1

What is the definition of resolution in imaging?

Answer 1

Accuracy in imaging

Resolution refers to the ability to distinguish between two structures in an image.

Question 2

What is axial resolution?

Answer 2

The minimum distance that 2 structures positioned front-to-back can be apart and still produce 2 distinct echoes

Axial resolution is not adjustable and ranges from 0.1-1.0 mm; lower values indicate better resolution.

Question 3

What is the formula for calculating axial resolution?

Answer 3

(mm) = SPL/2

SPL stands for spatial pulse length.

Question 4

What is another name for axial resolution?

Answer 4

Longitudinal, Range, Radial, or Depth resolution (LARRD)

These terms emphasize the directionality of axial resolution.

Question 5

What improves axial resolution?

Answer 5

• Higher frequency transducer
• Shorter spatial pulse length
• Shorter pulse duration
• Fewer cycles per pulse
• Lower numerical values

Higher frequency results in shorter pulses, enhancing resolution.

Question 6

What is lateral resolution?

Answer 6

The minimum distance that 2 structures positioned side-by-side can be apart and still produce 2 distinct echoes

Lateral resolution is perpendicular to the sound beam’s main axis.

Question 7

What is the formula for calculating lateral resolution?

Answer 7

(mm) = beam width

This indicates that lateral resolution is dependent on the width of the ultrasound beam.

Question 8

What is another name for lateral resolution?

Answer 8

Angular, Transverse, Azimuthal resolution (LATA)

These terms highlight the aspect of lateral resolution in imaging.

Question 9

What improves lateral resolution in the far field?

Answer 9

Higher frequency transducer

Higher frequency reduces beam divergence, enhancing lateral resolution.

Question 10

What are the focusing techniques for improving resolution?

Answer 10

• Fixed focusing
• Conventional or mechanical focusing
• Electronic focusing

These techniques can involve both external and internal methods.

Question 11

Does axial resolution change with depth?

Answer 11

No, it remains the same at all depths

Axial resolution is constant, regardless of depth.

Question 12

What is the best condition for axial resolution in the near field?

Answer 12

Highest frequency and fewest cycles

This results in the shortest spatial pulse length.

Question 13

What is the best condition for lateral resolution?

Answer 13

Narrowest beam width

Lateral resolution improves with smaller beam widths.

Question 14

What is the relationship between crystal diameter and lateral resolution?

Answer 14

• Smallest diameter crystal = best lateral resolution
• Largest diameter & highest frequency = least divergence

Larger crystals can provide better lateral resolution due to their ability to focus the beam more effectively.

Question 15

What happens to beam diameter in the near field as focal length is reduced?

Answer 15

Beam diameter decreases

This is part of the effects of focusing in ultrasound imaging.

Question 16

What is the effect of focusing on the focal depth?

Answer 16

Focal depth is shallower

A shallower focal depth can affect image quality and resolution.

Question 17

How does focusing affect beam diameter in the far zone?

Answer 17

Beam diameter in the far zone increases

This increase leads to more divergence of the beam.

Question 18

What is the effect of focusing on the focal zone?

Answer 18

Focal zone is smaller

A smaller focal zone can improve image clarity.

Question 19

Focusing only improves which type of resolution?

Answer 19

Lateral Resolution

Lateral resolution refers to the ability to distinguish two structures that are side by side.

Question 20

What are the characteristics of continuous wave frequency?

Answer 20

Continuous Wave

This type of frequency is used in specific ultrasound applications.

Question 21

What are the characteristics of pulsed wave frequency?

Answer 21

Pulsed Wave

Pulsed wave frequency is commonly used for imaging and diagnostics.

Question 22

What defines the focal length in ultrasound?

Answer 22

Focal Length

Focal length is a critical parameter affecting image quality.

Question 23

What is beam divergence?

Answer 23

Beam Divergence

Beam divergence describes how much a beam spreads out as it travels.

Question 24

What are the two types of resolution in ultrasound?

Answer 24

• Lateral Resolution
• Axial Resolution

Lateral resolution refers to the ability to distinguish side-by-side structures, while axial resolution pertains to the ability to distinguish structures along the axis of the beam.

Question 25

What determines sound beams?

Answer 25

Determinants of Sound Beams

These include various physical properties and parameters of the ultrasound system.

Question 26

What factors determine beam width?

Answer 26

• Frequency of electrical signal from ultrasound system
• Thickness and speed of sound of ceramic (PZT)
• Diameter and frequency of sound of ceramic

These factors play a crucial role in shaping the ultrasound beam.

Question 27

What does SPL stand for in ultrasound?

Answer 27

SPL

SPL stands for Spatial Pulse Length, an important factor in determining resolution.

Question 28

What does PD stand for in ultrasound?

Answer 28

PD

PD stands for Pulse Duration, which affects the quality of the ultrasound image.