phyiscs 5-7 patrt 1

These flashcards cover key concepts related to the interaction of sound and media, focusing on attenuation, half-value layer, impedance, reflection, transmission, and the characteristics of ultrasound in various media.

Attenuation

The reduction in the strength of ultrasound as it travels through a medium, composed of absorption, reflection, and scattering.

Half-Value Layer

The thickness of a medium required to reduce the intensity of ultrasound to half its original value.

Impedance

The acoustic impedance, which is the product of the medium's density and the speed of sound within it, influencing reflection and transmission.

Reflection

The return of sound waves when they hit a boundary between two different media.

Transmission

The passing of sound waves through a medium, critical for imaging structures deep in the body.

Acoustic Impedance

An important tissue property that influences the amount of reflection at tissue interfaces.

Attenuation in Bone

Significantly greater than attenuation in soft tissue.

Attenuation in Air

Greater than attenuation in soft tissue.

Attenuation Coefficient

In soft tissue, it approximates half of the ultrasonic frequency in megahertz (MHz).

Attenuation Units

Measured in decibels (dB).

Depth of Penetration

Increases as frequency decreases.

Half-Value Layer Thickness Factors

Depends on the medium and frequency of sound.

Types of Angles in Acoustic Waves

Acute (less than 90°), Right (exactly 90°), Obtuse (greater than 90°), with acute and obtuse angles also being classified as oblique.