A change in the frequency of waves, such as sound or light, received by an observer, when the source is moving relative to the observer. The frequency increases when the source is approaching and decreases when it is retreating. The Doppler effect is used in a number of medical applications...
Medical Definition Doppler effect noun : a change in the frequency with which waves (as sound, light, or radio waves) from a given source reach an observer when the source and the observer are in motion with respect to each other so that the frequency increases or decreases according to...
doi:DE2418426 A1LANZ, WERNER, DIPL.-PHYS. DR.MED., MUENCHENDE2418426A1 * Apr 17, 1974 Oct 30, 1975 Werner Dipl Phys Dr Med Lanz Ultrasonic Doppler effect applied to locate arteries and veins - ensuring successful medical puncture at first attempt...
The Doppler effect occurs because the shift in frequency is proportional to the speed of movement between the source and the receiver and therefore, it can be used to measure this speed. In medical imaging, the Doppler effect was initially used to measure the velocity of blood in large vessels...
The Doppler effect also has applications in medical physics. In a Doppler echocardiogram, sound waves of a certain frequency are channeled into the heart and reflect off of blood cells moving through the heart and blood vessels. Similar to the Doppler radar, cardiologists can understand the speed...
An alternative to utilizing the Doppler effect is to shift the analysis out of the frequency domain into the time domain. Called time domain analysis (TDA), this technique focuses on the ability to identify a “piece of blood” (RBC cluster) and follow its movement over time. By measuring ...
Doppler ultrasonography uses what is called the Doppler effect to measure the rate and direction of blood flow in the vessels. Just as a siren's pitch sounds higher when its source is moving toward you and lower as it moves away, so too will ultrasound waves change pitch, or frequency, as...
The carotid CW ultrasound patch (Flosonics Medical, Sudbury, Canada) is a wearable, non-invasive device (Fig. 3) that uses two continuous-wave 4 MHz ultrasound transducers; one transducer transmits sound continuously, while the other receives echoes continuously. The frequency of the received echo...
Fig. 13 shows the effect of an eye movement (angle δ) on the error in extracting the phase (phase shift Φm). Obviously the error is the higher the larger δ and the closer α to 90°. This also holds true for any error in the determination of the Doppler angle for other reasons...
Doppler ultrasound uses the Doppler effect created by moving objects, such as blood cells which are flowing through a blood vessel, to depict flow information. The Doppler effect consists of an acquired change in frequency of an ultrasound wave which occurs when the ultrasound wave is reflected of...