1PHYS 6720 - Lecture IX1Lecture IX Ultrasound Imaging1.Introduction2.Acoustic waves3.Acoustic detection4.Ultrasound and Doppler imagingPHYS 6720 - Lecture IX2IX-1IntroductionHistorical development•In 1870s, Francis Galton in England invented an ultrasound whistle to test the upper threshold frequency of human and animals and reported that the limit decreases as man ages•In 1880s, French physicists Pierre Curie and Jacques Curie observed the piezoelectric phenomenon of quartz crystal and other materials that laid foundation for ultrasound transducers •In 1920s and 30s, Sergei Y. Sokolov of Soviet Union, among others, reported detection of flaws metal objects with ultrasonic waves, first through transmission mode and later suggested improvement with a higher frequency (~3MHz) and a reflection mode •In 1945 and later, F.A. Firestone of University of Michigan filed several patents for flaw detection using a “supersonic reflectoscope”3IX-1IntroductionHistorical development•In 1941 and right after WWII, K.T. Dussik of Austria published a paper on medical use of ultrasound imaging (“On the possibility of using ultrasound waves as a diagnostic aid”) and experimental results with quartz transducers in transmission modeT1 - ultrasonic generator, Q1- transmitter, Q2 - receiver, T2 - converter amplifier, W – water bath, L - light, P - photographic/ heat-sensitive paperhttp://www.ob-ultrasound.net/dussikbio.htmlPHYS 6720 - Lecture IX4IX-1IntroductionHistorical development•After the rapid development of radar technology through WWII, several research groups in Japan, U.S. and Europe have pursued ultrasound detection equipment and ultrasound imaging devices•In 1958, Ian Donald published the first OBGY clinical paper on using pulse-echo technique in A and B-mode to diagnose a huge, easily removable, ovarian cyst in a woman who had been diagnosed as having inoperable cancer of the stomach •Wide applications of ultrasound in medical diagnosis started in 1960s in obstetrics and gynecology and other specialties when commercial equipment became available •The "First World Congress on Ultrasonic Diagnostics in Medicine" was held in Vienna in 1969 PHYS 6720 - Lecture IX5IX-1IntroductionHistorical developmentPublications on ultrasound imaging in OBGY increased from 1 in 1958 to 296 in 1978PHYS 6720 - Lecture IX6IX-1IntroductionAdvantage of ultrasound and Doppler imaging•No ionization radiation •Safety concerns include tissue temperature rise at low intensity and additional shock-wave generation under high-frequency and short-pulse (<~ns) conditions •So for diagnostic applications with low intensity and long-pulse (>~μs), ultrasound can be used in regular clinics by non-specialist physicians (do need training) •Fast signal acquisition: real-time imaging•Low-cost: an ultrasound imager costs between $30k and $100k
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