Doppler effect

Doppler effect

frequency of sound changes when a sound source and reflector move closer or further away

blood velocity flow

measured by the doppler effect

doppler shift

change in frequency

• Received - Transmitted

positive doppler shift

Received > Transmitted

• RBC moving towards the transducer

negative doppler shift

Received < Transmitted

• RBC moving away from the transducer

0 doppler shift

no movement

doppler equation

(2 * (ultrasound frequency) * Velocity * CosX) / sound of speed

1

Cos(0 degrees)

.87

Cos(30 degrees)

.5

cos(60 degrees)

0

cos(90 degrees)

-0.5

cos(120 degrees)

-0.87

cos(150 degrees)

-1

cos(180 degrees)

direct relationship

relationship between velocity and angle cosine

indirect relationship

relationship between cosine and angle