Definition of Hertz in an Ultrasound

Ultrasound can provide important details about the inner make-up of a living or inert medium. Though applicable to many fields, ultrasound is probably best known for its use in medicine.

History

Pierre and Marie Curie discovered Piezoelectricity, a concept that preceded ultrasonography. However, the use of ultrasound in the diagnosis and treatment of patients only began in the 1950's.

Nature of Ultrasound

Ultrasound is a type of non-ionizing radiation that uses inaudible high-frequency sound waves to produce an image of the tissue or organ being examined. It has the advantage of being less expensive and quicker to perform than MRI (magnetic resonance imaging).

Definition of Frequency

The Hertz is a general unit of frequency. In the context of ultrasound, it represents the number of complete cycles of sound per unit of time. One cycle per second equals one Hertz (Hz), while one thousand Hertz equals one kilohertz (KHz), and one million Hertz equals one megahertz (MHz)

Ultrasound Frequencies

In ultrasound, sound waves have a frequency greater than 20,000 Hertz (20 KHz). Medical ultrasound frequency typically ranges between 2 and 15 MHz

Ultrasound Bandwidth

Transducers convert energy to produce a pulse or echo for imaging. The range of frequencies in ultrasound transducers is known as bandwidth. An ultrasound equipment with broad bandwidth technology therefore has multiple operating frequencies.

Considerations

Compared to low-frequency ultrasound, high-frequency ultrasound tends to give better image resolution, but has a lower depth of penetration.

References

• The Ultrasound Store: Physical Principles of Ultrasound
• "Foot & Ankle Radiology;" Robert Christman, DPM; Churchill Livingstone; 2003

Resources

• Lunds University: History of Ultrasonography
• National Library of Medicine: Ultrasound