Doppler physical principles

Abstract

Doppler methodology has begun with the Austrian teacher's work Christian Andreas Doppler, in 1842, when he studied the desviation of frequency of the light emitted by stars. The first use of Doppler methodology in the medical area was made by Shigeo Satomura, in 1955, when he developed the first ultrasound equipment Doppler with the purpose of studding the heart’s movements. Since then, Doppler method has been improved and won fame in the medical middle with the development of equipments with specific uses like continuous wave Doppler, pulse wave Doppler, Color Doppler and Power Doppler. The physical principles of the Doppler methodology bases on the alteration of the frequency of reflected sound waves when the object reflector moves in relation to a sound wave source. The knowledge about the angle of insonation, pulse repetition frequency (PRF), volume of the sample and wall filter should be considered for a correct use of the Doppler velocimetry. The authors make revision about the historical and physical principles of Doppler, emphasizing on the most important points for the correct use of the Doppler velocimetry in the image diagnosis.