physics

Bandwidth

Difference between the upper and lower frequencies.

Narrow Bandwidth

Q-Factor: Higher

Image quality: Poor

Broad Bandwith

Q-Factor: Lower

Image quality: Improved

Higher Ensemble Length

Lower temporal resolution

Compression

Equalizes larger echoes with small ones. Decreases dynamic range

Demodulation

Converts Voltages deliver to the receiver.

Two components: Rectification and smoothing.

Axilal resolution

Short Pulse duration (PD) And short Spatial Pulse Length (SPL): improve Axial resolution

Axial Resolution

Two reflectors PARALLEL to the direction of sound beam

One in front of the other

Axial Resolution Synonyms

LARRD:

Longitudinal

Axial

Range

Radial

Depth

What is SPL decrease by?

The use of backing material in a transducer; Limits #of cycles

Is Frequency Increases what happens to Axial resolution?

It improves Axial resolution

Lateral Resolution

Two Reflectors: PERPENDICULAR to the direction of the sound beam.

Lateral Resolution: Synonyms

LATA

Lateral

Azimuthal

Transverse

Angular

Lateral Resolution

A narrow Beam width will IMPROVE Lateral Resolution

Lateral Resolution

Achieve by focusing.

Mechanical: Focused using a curved internal element or external lense

Array: Focused by way of electronic time delays

Lateral Resolution

Less Divergence is optimal to improve lateral resolution

Lateral Resolution in the Far field

Large Diameter, High Frequency active element transducer

Elevational Resolution

Thickness: slice thickness plane

Improves: as Thickness of elevational plane decreases

Elevational Resolution

1D Array uses a lens and 1.5D Array uses system electronics to focus.

Elevational Resolution

Thin Elevational plane is preferable to reduce slice thickness artifacts

Spatial Resolution

Overall detail of the image

High pixel density offer superior resolution

Pixel Density

The more pixels a display has, the better the SPATIAL RESOLUTION!!!

TEMPORAL RESOLUTION

Time required for acquisition of one imaging frame

Relevant to dynamic imaging

Frame Rate

FR