Introduction to Ultrasound Imaging

Study Notes

Ultrasound imaging (sonography) utilizes high-frequency sound waves to visualize internal body structures.
Captures real-time images, allowing observation of organ movement and blood flow.
Ultrasound operates beyond human hearing, using frequencies above 20 kHz, typically between 2-20 MHz.

Lazaro Spallanzani (1794) pioneered echolocation studies, discovering bats use sound, not light, for navigation.
Sir Francis Galton (1880) created equipment for producing 40 Hz sound waves.
Paul-Jacques and Pierre Curie (1880) discovered piezoelectricity, enabling electricity generation in quartz under mechanical vibration.
Paul Langevin (1915) developed sonar for submarine detection during WWI and invented the hydrophone as the first transducer.
Sy Sokolov (1928) proposed using ultrasound to detect flaws in metal structures.
Dr. Karl Dussik (1940) conducted the first medical ultrasound diagnosis to detect brain tumors using transducer placement on the head.
William Fry integrated computer technology into diagnostic ultrasound.
George Ludwig (early 20th century) studied ultrasound reflections from gallstones, highlighting varying acoustic impedances.
Ian Donald (1956) introduced ultrasound to medicine, utilizing A-mode to measure fetal head size.
Tom Brown invented the two-dimensional compound scanner, improving tissue density visualization.
Late 1950s saw the creation of the first contact compound B-scanner, producing static images with olive oil as lubricant.
The 1970s marked the introduction of gray scale imaging, enhancing echo amplitude display.
Mid-1970s introduced real-time scanning systems, offering dynamic sonographic information for the first time.
The Doppler technique was introduced in the 1980s, enhancing blood flow studies.

Thermal effects include slight temperature increases near the transducer, particularly significant at bone-tissue interfaces, with pulsed Doppler showing a higher heating potential.
Mechanical effects comprise cavitation, which involves pressure variations due to ultrasound waves.