Completion of the CCTS program provides the fellow with the didactic and experiential learning necessary to conduct NIH-funded clinical and translational research.
Joseph Woo [ Part 2 ] [ Part 3 ] [ Site Index ] he story of the development of ultrasound applications in medicine should probably start with the history of measuring distance under water using sound waves.
Ultrasound scanners can be regarded Thesis in obstetrics and gynecology a form of 'medical' Sonar. As early asJean-Daniel Colladona Swiss physicist, had successfully used an underwater bell to determine the speed of sound in the waters of Lake Geneva. In the later part of the s, physicists were working towards defining the fundamental physics of sound vibrations wavestransmission, propagation and refraction.
One of them was Lord Rayleigh in England whose famous treatise " the Theory of Sound " published in first described sound wave as a mathematical equation, forming the basis of future practical work in acoustics. As for high frequency 'ultrasound', Lazzaro Spallanzanian Italian biologist, could be credited for it's discovery when he demonstrated in the ability of bats navigating accurately in the dark was through echo reflection from high frequency inaudible sound.
Very high frequency sound waves above the limit of human hearing were generated by English scientist Francis Galton inthrough his invention, the Galton whistle.
The real breakthrough in the evolution of high frequency echo-sounding techniques came when the piezo-electric effect in certain crystals was discovered by Pierre Curie and his brother Jacques Curie in Paris, France in They observed that an electric potential would be produced when mechanical pressure was exerted on a quartz crystal such as the Rochelle salt sodium potassium tartrate tetrahydrate.
The reciprocal behavior of achieving a mechanical stress in response to a voltage difference was mathematically deduced from thermodynamic principles by physicist Gabriel Lippman inand which was quickly verified by the Curie brothers.
It was then possible for the generation and reception of 'ultrasound' that are in the frequency range of millions of cycles per second megahertz which could be employed in echo sounding devices.
Further research and development in piezo-electricity soon followed. Underwater sonar detection systems were developed for the purpose of underwater navigation by submarines in World war I and in particular after the Titanic sank in Alexander Belm in Vienna, described an underwater echo-sounding device in the same year.
The first patent for an underwater echo ranging sonar was filed at the British Patent Office by English metereologist Lewis Richardson, one month after the sinking of the Titanic.
The first working sonar system was designed and built in the United States by Canadian Reginald Fessenden in The Fessenden sonar was an electromagnetic moving-coil oscillator that emitted a low-frequency noise and then switched to a receiver to listen for echoes.
It was able to detect an iceberg underwater from 2 miles away, although with the low frequency, it could not precisely resolve its direction. The turn of the century also saw the invention of the Diode and the Triode, allowing powerful electronic amplifications necessary for developments in ultrasonic instruments.
Patents were filed in France and the United States. They called their device the ' hydrophone '. The transducer of the hydrophone consisted of a mosaic of thin quartz crystals glued between two steel plates with a resonant frequency of KHz.
Between and the hydrophone was further improved in classified research activities and was deployed extensively in the surveillance of German U-boats and submarines. The first known sinking of a submarine detected by hydrophone occurred in the Atlantic during World War I in April, Langevin's hydrophones had formed the basis of the development of naval pulse-echo sonar in the following years.
By the mid s, many ocean liners were equipped with some form of underwater echo-sounding range display systems.
In another development, the first successful radio range-finding experiment occurred inwhen British physicist Edward Appleton used radio echoes to determine the height of the ionosphere.
The first practical RADAR system Radio Detection and Ranging, and using electromagnetic waves rather than ultrasonics was produced in by another British physicist Robert Watson-Wattand by England had established a chain of radar stations along its south and east coasts to detect aggressors in the air or on the sea.
World war II saw rapid developments and refinements in the naval and military radar by researchers in the United States. Such radar display systems had been the direct precursors of subsequent 2-dimensional sonars and medical ultrasonic systems that appeared in the late s. Books such as the "Principles of Radar" published by the Massachusetts Institute of Technology M I T Radar school staff in detailed the techniques of oscilloscopic data presentation which were employed in medical ultrasonic research later on see below.
Two other engineering advances probably had also influenced significantly the development of the sonar, in terms of the much needed data aqusition capabilities: Yet another parallel and equally important development in ultrasonics which had started in the 's was the construction of pulse-echo ultrasonic metal flaw detectorsparticularly relevant at that time was the check on the integrity of metal hulls of large ships and the armour plates of battle tanks.
The concept of ultrasonic metal flaw detection was first suggested by Soviet scientist Sergei Y Sokolov in at the Electrotechnical Institute of Leningrad.
He showed that a transmission technique could be used to detect metal flaws by the variations in ultrasionic energy transmitted across the metal.
The resolution was however poor. He suggested subsequently at a later date that a reflection method may be practical. The equipment suggested by Sokolov which could generate very short pulses necessary to measure the brief propagation time of their returning echoes was not available until the s.
Because of the war, the reflectoscope was not formally published until Feedback and revision.
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About the Gynecologic Oncology Program The Department of Obstetrics and Gynecology offers an ACGME-accredited three-year fellowship in gynecologic oncology under the direction of Dr. Teresa Rutledge, Associate Professor of Obstetrics and Gynecology.
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