Module 4 Review Flashcards
The ability to distinguish 2 structures lying close together is called what?
Spatial resolution
He ability to distinguish 2 structures lying close along the length of the beam is called what?
Axial resolution
The ability to distinguish two structures lying close together across the beam axis is called what?
Lateral resolution
The three types of spatial resolution are what?
- Axial
- Lateral
- Elevational
Axial resolution can also be called what type of resolution?
- Longitudinal
- Range
- Depth
How do these affect axial resolutions (AR)?
1. Increase frequency
2. Increase damping
3. Increase bandwidth
4. Increase Q factor
- Improves AR
- Improves AR
- Improves AR
- Degrades AR
What is the axial resolution in soft tissue using a 3 MHz pulse having 4 cycles?
= 1/2 SPL = 1/2(lamda + RD)
= 1/4((C/F) +RD)
= 1/2 ((1.54/3) + 4)
= 1/2 (2)
= 1mm
Which type of resolution (axial or lateral) is the best in most ultrasound systems?
Axial
Give three synonyms for lateral resolution
- Angular
- Transverse
- Azimuthal
Is lateral resolution equal to bandwidth
No it is equal to beam width
Does lateral resolution change along the length of the beam?
Yes
What affect does the following actions produce with regard to lateral resolution (LR)?
1. Increase frequency of transducer
2. Increase diameter of the transducer crystal
3. Increase distance to the reflector
- Improves LR
- Improves LR
- Best at the focal zone
Can lateral resolution in the far field be improved by focusing?
No
Can reducing the SPL by increase frequency improve axial resolution
Yes, in the midfield
Can electronic focusing improve axial resolution?
No
