The Basics of Ultrasound

How it works


Sound waves are produced by vibration from the crystal of the probe. They hit tissue and based on wave frequency and tissue properties are altered.


Wave length = Propagation velocity of the tissue/ Frequency

Sound waves hit tissues and have one of the above actions. Based on how fast and how intense the sound waves return results in depth and color. See below for colors 

ALara

As low as reasonably achievable

Limit scan time

Use the lowest power function ( less doppler, appropriate machine presets)

Lowest MI (mechanical index) and TI (thermal index)

Probe motions


the modes 

B Mode used for most structural and anatomical questions

M Mode used for motion- pneumothorax (lungs sliding), TAPSE, MAPSE, Fetal Heart Tones (lowest energy), diaphragm excursion

Color doppler used for detection and direction of flow

Power doppler tells you presence of flow but no direction or velocity. Good for low flow states

Pulse wave doppler tells you direction, velocity and phasicity of flow

Tissue doppler is used for tissue compliance. Measures tissue movement

ultrasound ethics

Basic US Slides