Ultrasound Physics Chapter 11

Three basic modes of display or format:

1) Amplitude mode

2) Brightness mode

3) Motion mode

A-mode

Amplitude

(Used a lot in ophthalmology)

A-mode appears as:

A series of upward spikes

X-axis of an A-mode display represents:

reflector depth

(derived from the time-of-flight of sound pulse)

Y-axis of an A-mode display represents:

reflection amplitude

On A-mode, strong echoes create:

Tall spikes

B-mode

Brightness

(Basis for gray scale imaging, including real-time imaging)

B-mode appears as:

A line of dots of varying brightness

Weaker reflections appear as:

darker gray dots

(Stronger reflections; brighter white dots)

X-axis of a B-mode represents:

reflector depth

(derived from the time-of-flight of sound pulse)

Z-axis in B-mode represents:

When displayed on an oscilloscope, this is the amplitude information or the brightness of the dot

M-mode

Motion

(used to assess the motion of cardiac walls and structures)

M-mode appears as:

a group of horizontal wavy lines

A straight horizontal line indicates:

a stationary reflector

X-axis of an M-mode represents

time

Y-axis of an M-Mode represents

reflector depth

(derived from the time-of-flight of a sound pulse)

Sampling rate of M-mode

is very high and equal to the pulse repetition frequency

On A-mode, weak echoes create:

short spikes

A-mode is extremely accurate in determining ___

the depth of reflectors

A-mode is used extensively in ___

ophthalmology

B-mode is the first __

form of gray scale imaging

B-mode is the basis for ___

all other types of gray scale imaging, including real time

Which mode is the only one to track reflectors location with respect to time?

M-mode

The ability to distinguish two structures lying close together front to back is called?

axial resolution

The best lateral resolution is determines by?

the width of the sound beam - narrower beams have better resolution