79. ULTRASOUNDS: LATERAL RESOLUTION

Question 1

1. What is Lateral Resolution?

Answer 1

• it is the ability to distinctly identify two structures that
  are very close together
• these structures are side by side to the sound beam’s
  main axis
• they can also be perpendicular to the sound beam’s
  main axis

Question 2

2. What does Lateral Resolution tell us about?

Answer 2

• it tells us about the minimum distance that two
  structures can be apart from each other
• and still produce two distinct echoes on an Ultrasound
  image

THESE STRUCTURES:
- are positioned side by side

Question 3

3. What determines the Lateral Resolution?

Answer 3

• it is determined by the width of the ultrasound beam
• it is measures in mm

Question 4

4. What is Lateral Resolution controlled by?

Answer 4

• it is controlled by focusing the beam
• this beam can be focused by the acoustic lens
• it can also be curved by a Piezoelectric crystal

IT ALSO DEPENDS ON THE:
- Beam Diameter

Question 5

5. Where is Lateral Resolution the best?

Answer 5

• it is best at the focus where the beam is narrowest
• it is good within the focal zone

Question 6

6. What do these images show?

Answer 6

THE ECHOES DIAMETER NEEDS TO BE SMALLER:
- than the two infractions in the Lateral Resolution
- this produces a better image

Question 7

7. In clinical situations, which kind of resolution is better?

Answer 7

• Axial Resolution
• this is because the ultrasound pulses are shorter than
  they are wide

THIS MEANS THAT:
- the numerical value for axial resolution is less than the
value for lateral resolution

Question 8

8. What kind of frequencies improve both axial and lateral resolutions?

Answer 8

• high frequencies

Question 9

9. How is Axial Resolution improved?

Answer 9

• it is improved in the entire image by shorter pulses
• this is because they are associated with higher
  frequency sounds

Question 10

10. How is Lateral Resolution improved in the far field?

Answer 10

• it is improved because of the higher frequency pulses
• they diverge less in the far field
• the beams are narrower

Question 11

11. What is the Orientation of Axial Resolutions?

Answer 11

• it is front to back
• it is parallel to the beam

Question 12

12. What is the Orientation of Lateral Resolution?

Answer 12

• it is side by side
• it is perpendicular to the beam

Question 13

13. What is the Axial Resolution determined by?

Answer 13

• it is determined by the pulse length

Question 14

14. What is the Lateral Resolution determined by?

Answer 14

• it is determined by the beam width

Question 15

15. What characteristics make the Axial Resolution the best?

Answer 15

• shorter pulses
• higher frequency
• fewest cycles

Question 16

16. What characteristics make the Lateral Resolution the best?

Answer 16

• having the narrowest beam

Question 17

17. What factors can change the Axial Resolution?

Answer 17

• it can change somewhat at all depths
• it does not change with focus

Question 18

18. What factors can change the Lateral Resolution?

Answer 18

• it changes at all depths
• it is the best at the focus

Question 19

19. What conditions are the best for Axial Resolutions in the near field?

Answer 19

• shortest pulse

Question 20

20. What conditions are the best for Lateral Resolutions in the near field?

Answer 20

• smallest diameter crystal

Question 21

21. What conditions are the best for Axial Resolutions in the far field?

Answer 21

• shortest pulse

Question 22

22. What conditions are the best for Lateral Resolutions in the far field?

Answer 22

• largest diameter
• highest frequency