Ultra note 2

Absorption

Conversion of sound energy into heat energy.

Ultrasound Scanning

The PX does not feel the heat because it easily spreads out.

Attenuation

Absorption is the dominant factor in this process.

Rayls

Unit of absorption.

Reflection

Very important concept; foundation of diagnostic ultrasound.

Specular Reflection

Reflection coming from smooth surfaces.

Back Scattering

Reflection coming from rough surfaces.

Rayleigh-Tyndall Effect

Reflection coming from microscopic structures.

Acoustic Impedance

Physical property of tissue; determines the percentage of wave transmission and reflection.

Impedance Matching

Process that decreases reflection.

Coupling Agent

Substances applied in impedance matching.

Critical Angle

Incident angle in which total internal reflection occurs.

Bandwidth

Useful range of frequency over which anything can operate.

Beamwidth

Determined by the diameter of the probe or transducer.

Fresnel Zone

Beam nearest to the source; also known as near field.

Fraunhofer Zone

Beam farther from the source; described as a divergent beam.

A-Mode (Amplitude)

Displayed as spikes; represents amplitude.

B-Mode (Binary and Brightness)

Produces gray scale; incorporated in modern ultrasound machines.

C-Mode (Constant)

Used in Doppler applications.

M-Mode (Motion)

Represented by a single acoustic line; used in echocardiography.

Real-Time Ultrasound

Demonstrates the accurate structural movement of what is scanned.

Doppler Imaging

Imaging that uses the principle of shift for blood flow assessment.

Resolution

Refers to the clarity of an ultrasound image.