Ultrasound imaging
HISTORY
: Milestone applications
• publication of The Theory of Sound (Lord Rayleigh, 1877)
• discovery of piezo-electric effect (Pierre Curie, 1880)
- enabled generation and detection of ultrasonic waves
• first practical use in World War One for detecting submarines
• followed by
- non-destructive testing of metals (airplane wings, bridges)
- seismology
• first clinical use for locating brain tumors (Karl Dussik,
Friederich Dussik, 1942)
• the first greyscale images were produced in 1950
- in real time by Siemens device in 1965
• electronic beam-steering using phased-array technology in 1968
• popular technique since mid-70s
• substantial enhancements since mid-1990
Advantages
• non-invasive
• inexpensive
• portable
• excellent temporal resolution
Disadvantages
• noisy
• low spatial resolution
Samples of clinical applications
• echo ultrasound
- cardiac
- fetal monitoring
• Doppler ultrasound
- blood flow
• ultrasound CT
- mammography
US waves are longitudinal compression waves
•particles never move far
• transducer emits a sound pulse which compresses the material
• elasticity limits compression and extends it into a rarefaction
• rarefaction returns to a compression
• this continues until damping gradually ends this oscillationSEE IMAGE IN thePDF
• ultrasound waves in medicine > 2.5 MHz
• humans can hear between 20 Hz and 20 kHz (animals more)
Generation of Ultrasonic Waves
Via piezoelectric crystal
• deforms on application of electric field ?? generates a pressure wave
• induces an electric field upon deformation ? detects a pressure wave
• such a device is called
see image in PDF
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing.
Although this limit varies from person to person,
it is approximately 20 kilohertz (20,000 hertz) in healthy, young adults and thus,
20 kHz serves as a useful lower limit in describing ultrasound.
The production of ultrasound is used in many different fields,
typically to penetrate a medium and measure the reflection signature or supply focused energy.
The reflection signature can reveal details about the inner structure of the medium,
a property also used by animals such as bats for hunting.
The most well known application of ultrasound is its use in
sonography to produce pictures of fetuses in the human womb.
There are a vast number of other applications as well
clinical application
obstetric & gynecology -1
genitourinary system -2
gasteroentestinal system-3
neuorology -4
mskuloskletal system -5
Etc
obstetric & gynecology -1
genitourinary system -2
gasteroentestinal system-3
neuorology -4
mskuloskletal system Etc -5
obstetric & gynecology -1
genitourinary system -2
gasteroentestinal system-3
neuorology -4
mskuloskletal system Etc -5
N.B ; when we talk about the ultra sound clinica applicaion ; we concentrate on the dagnostic part of usapplication although therapeutic application as as in the treatment of prostatic enlargmet &wide range of applicaion in the plastic surgey & th diagnostic application in obstetric ;include as example ; gestational ge ; amonnt of liquior ; congeital abnormality ;placentae ; presentation of fetus ........etc add to minocentesisasgene therapy
obstetric & gynecology-1
genitourinary system -2
gasteroentestinal system-3
neuorology-4
mskuloskletal system Etc -5