RIU 324 Lecture 34: Harmonics Powerpoint
12 Apr 2020
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Document Summary
Harmonic imaging: creation of an image using sound waves that are twice the frequency of the fundamental frequency. A. as a sound travels through tissue, the high-pressure bit (compressing tissue) moves faster than the rarefactional component: this distorts the wave! And generates higher frequency components ( harmonics ) deep in the tissues. C. eg 3mhz wave creates 6mhz, 12 mhz harmonics. D: therefore harmonics arise from the nonlinear behavior of the ultrasound wave in the tissue, fundamental frequency: the frequency transmitted into the body (created by the transducer, harmonic frequency: twice the funadmental frequency a. k. a. H. harmonics are created during ultrasound propagation: not produced upon reflection, the machine filters out the fundamental frequency upon signal return. K therefore only the harmonic signals are displayed: the displayed signals are weaker. Interfering signals are suppressed and contrast is improved. Harmonic imaging with an axial and lateral resolution.
