Doppler Effect and Doppler Instrumentation - Vocabulary Flashcards

Vocabulary flashcards covering the Doppler effect, Doppler shift, Doppler types, instrumentation, and clinical applications.

Doppler Effect

Change in frequency of a wave in relation to an observer moving relative to the wave source.

Christian Doppler

Austrian scientist who first described the Doppler Effect in 1842 for waves such as sound and light.

Doppler Shift

Change in observed frequency due to relative motion between the wave source and the observer.

Positive Doppler Shift

Flow toward the transducer.

Negative Doppler Shift

Flow away from the transducer.

f' (observed frequency)

The frequency actually detected by the observer after the Doppler shift.

f (actual frequency)

The original emitted or intrinsic frequency of the wave.

v (speed of sound)

Propagation speed of the sound wave in the medium.

vo (velocity of observer)

Speed and direction of the observer relative to the medium.

vs (velocity of source)

Speed and direction of the wave source relative to the medium.

Doppler shift formula

f' = f(v + vo) / (v - vs); relates observed frequency to actual frequency and velocities.

Continuous Wave (CW) Doppler

Uses two crystals (one to transmit, one to receive); measures high-velocity flows; no range resolution.

Pulsed Wave (PW) Doppler

Uses a single crystal that transmits and receives alternately; provides depth-specific sampling (range resolution).

Aliasing

Occurs in PW Doppler when velocity is too high, causing incorrect frequency interpretation.

Color Doppler

Overlays flow information in color on a B-mode image; color indicates direction (toward vs. away).

BART

Mnemonic: Red = toward, Blue = away (color coding in Doppler imaging).

Power Doppler

Detects the strength of the Doppler signal without giving flow direction or speed; more sensitive to low flow.

Doppler Instrumentation

Categories of Doppler systems including RADAR, SONAR, MEDICAL IMAGING, and OPTICAL DOPPLER.

RADAR SYSTEMS

Use radio waves to detect motion via Doppler shifts.

SONAR SYSTEMS

Use sound waves to detect motion via Doppler shifts.

MEDICAL IMAGING

Doppler techniques used in ultrasound for medical imaging and assessment of flow.

OPTICAL DOPPLER

Uses light to measure Doppler shifts (optical methods).

Cardiology (Doppler applications)

Assess valve diseases and heart chamber pressures.

Obstetrics (Doppler applications)

Monitor fetal circulation in the umbilical artery or middle cerebral artery.

Vascular Imaging

Detect blood clots, stenosis, or arterial plaque.

Organ Perfusion

Check kidney, liver, or transplant viability using Doppler assessment.

Umbilical Artery

A fetal circulation vessel commonly examined in obstetric Doppler studies.

Middle Cerebral Artery

A fetal circulation vessel often evaluated in obstetric Doppler studies.

Turbulence

Disturbed or irregular blood flow detectable by Doppler imaging.

Flow direction

Direction of moving blood relative to the transducer; toward or away.