BRAINCAKEDoppler Imaging
Doppler imaging uses ultrasound to measure the speed of blood flow, for example to find narrowed arteries or check blood flow through the heart and the placenta.
Ultrasound of frequency f is directed at a blood vessel. It is reflected by moving red blood cells, and the reflected ultrasound has a changed frequency because of the Doppler effect. If the blood is moving towards the transducer the reflected frequency is higher; if it is moving away, the reflected frequency is lower.
The change in frequency (Doppler shift) is
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Key terms in this lesson
- doppler effect
- The change in the observed frequency or wavelength of a wave caused by relative motion between its source and the observer.
More in Medical Imaging
- PET Scanning
- Ultrasound
- The Piezoelectric Effect
- Ultrasound Transducers
- A-scans and B-scans
- Acoustic Impedance
- Reflection at Boundaries
- Impedance Matching and Coupling Gel
All 20 lessons in Medical Imaging · All OCR A-level Physics topics