UNIT 10 RESOLUTIONS

Axial resolution describes the accuracy related to visualizing two structures that are ___ to a sound beam’s main axis

Parallel

System X has axial resolution of 0.7 mm whereas System D’s is 0.4 mm. Based on this information, which system will produce the better quality picture?

System D

The axial resolution of an imaging system is reported to be 0.85 mm at the beam’s focus. What is the closest estimate of the system’s radial resolution at a location that is 5 cm deeper than the focus?

Equal to 0.85 mm

What primarily determines axial resolution in ultrasound imaging?

Spatial pulse length

How can axial resolution be improved?

Using a higher frequency transducer

Which transducer has the best axial resolution?

2 cycles/pulse, 4 MHz

Two ultrasound systems produce pulses. One pulse is 0.4 usec in duration and the other is 0.2 usec long. Which pulse is most likely to provide the best radial resolution?

0.2 usec

Lateral resolution is best at which part of the ultrasound beam?

At the focus

What determines lateral resolution?

Beam width

Which factor worsens lateral resolution

Beam divergance

Axial resolution improves when spatial pulse length is:

Shortened

Which transducer characteristic improves lateral resolution?

A larger aperture

Lateral resolution is measured in which direction?

Perpendicular to the beam

What is the formula for axial resolution?

SPL / 2

What happens to lateral resolution in the far field?

It worsens due to beam divergence

Which resolution is typically better in diagnostic ultrasound?

Axial resolution

Which phenomenon most degrades lateral resolution in tissue with a high speed of sound variability?

Phase aberration

What is the primary effect of dynamic receive focusing on lateral resolution?

It maintains optimal beam width across varying depths

Which factor limits the maximum achievable lateral resolution improvement from electronic focusing?

DiffractionBa

Which focusing method provides the greatest improvement in lateral resolution for a linear array?

Multiple transmit focal zones

The focus of an ultrasound beam is the location where the ____

Optimum transverse resolution is

Two ultrasound systems have near zone lengths of 8 cm. At the focus, System G’s lateral resolution is 3.0 mm, whereas System P’s is 5.0 mm. Which system will produce higher quality pictures at their foci?

System G

The lateral resolution of an ultrasound system is 4 mm. Two structures are separated by 3 mm and lie side by side in relation to the sound beam’s main axis. What will most likely appear on the system’s display

One echo

What will lower the value of an ultrasound system’s lateral resolution?

Use an acoustic lens

You suspect that a bright spot on the B-mode image is a calcification but there is no posterior shadowing. How can you best optimize your system to demonstrate a shadow distal to the calcification?

Increase the transducer frequency

Which of the following adjustments will improve the ability to distinguish two structures that lie side‑by‑side

Increase scan line density

Which of the following best describes the f-number?

Focal length divided by the aperature

Spatial resolution consist of:

Lateral and axial resolution

All of the following are other names of axial resolution except:

Azimuthal resolution

All of the following are other names of lateral resolution except:

Longitudinal resolution

When you increase the scan line density in the B-mode image, you improve:

Lateral resolution

Which represents the best measure of resolution for modern day ultrasound scanners?

Axial

What is the advantage of using multiple transmit focal zones?

Increases lateral resolution

Which of the pulses produced from a 7 MHz transducer would have the best lateral and axial resolution?

2 mm beam diameter, 3 pulses per cycle