Section IV - 41
Ultrasound

Direct measurement of the natural resonant frequencies of varying tissue compositions averaged over time. Indirect measurement of the electromagnetic waves emitted by movement of ions across cellular membranes. Generation of sound waves by a piezoelectric element, the reflections of which are measured by the element and processed by a computer. Direct measurement of microscopic oscillations of molecules, filtered through a white noise generator. Generation of low-intensity ionizing radiation that penetrates tissues of varying density in a characteristic pattern.