2012年5月15日 星期二

Ultrasound History


The history of ultrasound began with SONAR (Sound Navigation and Ranging) for submarines and has had many uses with varying degrees of success since then.

Ultrasound history, medically speaking, has been primarily a diagnostic technology although it has been tested and used for therapy as well. Doctors and sonographers have been capturing images from within the human body since the 1940's and in spite of its varied history, ultrasound has become one of the most widely used medical diagnostic tools in modern medicine.



When was ultrasound testing invented? 1826.

Who invented ultrasound? Swiss physicist, Jean-Daniel Colladon.

How was ultrasound discovered? Colladon used an underwater bell to determine the speed of sound in the water.

How did ultrasound history progress to what is in 2010?

Many studied sound vibrations (waves), transmission, propagation, and refraction throughout the 1800's.
English Lord Rayleigh published in 1877 "the Theory of Sound" & first described a sound wave as a mathematical equation, forming the basis of future practical work in acoustics.
Italian biologist, Lazzaro Spallanzani, in 1794 demonstrated the ability of bats to navigate accurately in the dark via echo reflections from high frequency inaudible sound or 'ultrasound'.
High frequency sound waves (above the limit of human hearing) were generated by English scientist Francis Galton in 1876, through the Galton whistle, which was his invention.
Austrian physicist Christian Doppler and Buys Ballot in 1845 proved the Doppler Effect on sound waves: A sound's pitch would change if its source or recipient was in motion. This was a very significant change to the future of ultrasound.
It was discovered in Paris, France in 1880 by Pierre Curie and his brother Jacques Curie, that electric potential would be produced when mechanical pressure was exerted on a quartz crystal.
The opposite of which was mathematically deduced from thermodynamic principles by physicist Gabriel Lippman in 1881. The generation and reception of 'ultrasound' was now possible.
Underwater sonar detection systems were developed for the purpose of underwater navigation by submarines in World war I.
The first working sonar system was designed and built in the United States by Canadian Reginald Fessenden in 1914. This system was able to detect an iceberg underwater from 2 miles away. Powerful electronic amplifications were necessary for developments in ultrasonic instruments:

French physicist Paul Langevin and Russian scientist Constantin Chilowsky developed an ultrasonic echo-sounding device called the 'hydrophone', the basis of the development of naval pulse-echo sonar.
Discoveries and developments parallel to echo sound, such as electro-magnetic RADAR;
ENIAC, the first digital computer;
and the point-contact transistor.





In the Medical field, the heating and disruptive effects of ultrasound were applied to therapy, also as a neuro-surgical tool, before being used in the 1940's for diagnosis.Karl Theo Dussik, a neurologist/psychiatrist at the University of Vienna, Austria, and his brother Friederich, a physicist, first employed ultrasound in medical diagnosis by attempting to locate brain tumors by sending an ultrasound beam through the skull which produced an A-mode image. The amplitudes seen on the image showed both sides of the skull and the midline of the brain. If a midline shift was seen, a conclusion was made that there was either a tumor or a bleed. The "image" was recorded photographically on heat-sensitive paper.


Ultra sound waves are currently most commonly associated with their application to ultrasound machines. Read about how ultrasound machines emit ultra sound in this one page overview on DrSmart.com from Smartsound Ultrasound.





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