13 Harmonics Flashcards
What is harmonic imaging?
Ultrasound scans from sound reflections at twice the transmitted frequency
What are harmonics?
Multiples of transducer frequency and is created in the tissues
What is the fundamental frequency?
Frequency of the transmitted sound wave
What is harmonic frequency?
Twice the transmitted frequency, also called second harmonic
What is non-linear behavior?
The small difference in speeds between regions of compression and rarefaction
What type of behavior creates harmonics?
Non-linear behavior
How does sound move between regions of compression and rarefaction?
Slightly faster in compression
Slightly slower in rarefaction
What is pulse inversion harmonic imaging?
Positive and negative pulses transmitted down each scan line in which the negative (inverse) pulse cancels the fundamental reflections because of destructive interference
What is the major disadvantage of pulse inversion imaging?
Frame rate is 1/2 of fundamental imaging and degrades temporal resolution, but improves spatial resolution
What type of transducer is used for pulse inversion harmonics?
Wide-bandwidth or broadband transducers
