Resolution

What are four types of resolution

detail

contrast

temporal

elevational*

 

With detail resolution if 2 reflectors are not sufficiently separated, they will not

produce separate reflections and not be separated on

What are the two types of the detail resolution?

Axial

Lateral

What does axial and lateral both depends on ?

both are dependent on ultrasound pulse characteristics as they travel through tissue

What is axial resolution

the minimum reflector separation required along the direction of travel to produce separate echoes

Axial Resolution AKA?

●longitudinal

●range

●depth

●“LARD”

LARD aka?

Longitudinal, axial, range. radial, depth

What is the formula for axial resolution?

axial resolution (mm) = ½ SPL (mm)

In axial the smaller the number, the better ?

The quality

As SPL goes down the value of axial resolution goes

Down(better quality)

As SPL goes down the value of axial resolution goes

Down(better quality)

As cycles per pulse goes up the number value of axial resolution goes

Up(reduced quality)

As frequency goes up, axial resolution value goe

Down( improves)

How does damping material improve axial resolution

by decreasing cycles per pulse

Lateral Resolution is the minimum reflectors can be separated perpendicular to the direction of sound travel so that two separate _______ are produced

Echos

Lateral resolution aka

, angular, transverse, azimuthal, “LATA”

Lateral resolution =

beam width or diameter (mm)

As beam width goes down, lateral resolution value goes

down (improves)

as focusing goes up lateral resolution value goes

down(improves)

As frequency goes up lateral resolution value goes

Down(improves)

Lateral and axial resolution are best in the ?

Focal region

Low axial or lateral number value means quality

Improves

• If they give SPL and ask for axial resolution

Divide by 2

high axial or lateral number value means quality

Degrades

Axial resolution is usually ______ than lateral resolution and why

better, because pulse it typically wider than tall

Both resolutions are usually

better than system can display

Reminder-focusing the beam may be performed by?

Curving the element

Using a lens

Phasing

Multiple focus can be used to create

a long focal region

• If they give axial resolution and ask for SPL

• → multiply by 2

what is the Formula if soft tissue is stated in the sentence and asking for the Axial resolution?

●SPL = __x 1.54 mm/µs

                         _ MHz

Lateral resolution aka?

●angular

●transverse

●azimuthal

●“LATA”

What is the formula for lateral resolution

lateral resolution (mm) = beam width or diameter (mm)

 

lateral and axial resolution are best in?

best in the focal region

 

axial resolution is usually better than lateral

Yes or no?

Yes

you need multiple lines or pulses to create multiple

Focal regions

multiple lines or pulses take more

Time to create one image or frame

Frame rate ________ _________ with multiple focal regions

Slow, down

Multi focus can be obtained by using

Dynamic aperture

Dynamic aperture means ?

firing only inner elements of the group for a short focus and the outer elements for a deeper focus

Dynamic focusing is a process where

an array transducer can listen for echo's within a focal region

Dynamic focusing is not output focusing but a

Receiving focus

the receiving focus combined with single focus or multi focus greatly

Improved resolution at all depth

acoustic energy may be emitted by a transducer in a direction different that the main axis this is called

Grating lobes

Single element transducers produce _______ lobes while array transducer produce _______ lobes

Side, grating

A grating lobe results in unwanted sound beams which may bring back

inaccurate echo infromation

What process can eliminate extra beams (grating or side lobes)

Apodization or sub-dicing