The development history of ultrasound imaging (part one)
Ultrasound refers to a sound wave with a vibration frequency higher than 20KHz, which has the characteristics of strong penetrating power and good directionality. In nature, some animals use ultrasound to detect surrounding targets or obstacles, and this also gives mankind enlightenment. With the discovery of piezoelectric materials at the end of the 19th century and the smooth realization of industrialization, ultrasound has rapidly developed in the fields of space ranging and target detection, and new applications such as sonar and medical imaging have been born. The application of ultrasound imaging in medicine has a long history. With the rapid development in recent decades, mature imaging processing procedures have been formed.
The first written report on the use of sound waves for spatial positioning can be traced back to 1794. LazaroSpallanzani ("Opus coli difisica") analyzed the basic mechanism of bats for spatial positioning and believed that bats used other mechanisms for positioning rather than visual space. Positioning.
By 1880, Galto created and produced equipment capable of generating sound waves with a frequency of 40.000 Hz. In the same year, the Jacques et Pierre Curie brothers pointed out that the mechanical vibration of quartz crystals can generate electricity, and this phenomenon is now called the piezoelectric effect. The brothers Jacqueset Pierre Curie also discovered the inverse piezoelectric effect. Quartz crystals can vibrate under the action of electric charge changes to form ultrasonic waves. In 1912, Richardson invented an echolocator based on the concept of ultrasound, which was used to navigate and detect objects in the water. In 1929, Sokolov proposed the theory of sound propagation, and in the early 1930s began to use ultrasound to detect internal defects in metal structures. In 1937, the Dussig brothers tried to use ultrasound to show the structure of the ventricle, but their attempt was unsuccessful because ultrasound could not penetrate the bone structure. Ludwig and Stuters began to use pulsed ultrasound to detect gallbladder stones in the 1940s. In 1956, Ian Donald actually used one-dimensional mode (A-mode ultrasound) to measure the diameter of the parietal lobe of the fetal head in practice. Two years later, Donald and Brown released ultrasound images of female genital tumors. At the same time, Brown invented the so-called "two-dimensional compound scanner", which enables examiners to observe and analyze the density of tissues. This is often referred to as the turning point in the medical application of ultrasound.
In 1942, an Austrian doctor pioneered the application of penetrating ultrasound imaging in human brain diagnosis. Although the imaging effect of the brain image obtained by this method was very poor, he innovatively introduced ultrasound imaging into clinical medical diagnosis. , This work is still regarded as a milestone in the field of medical ultrasound imaging. Since then, with the deepening of ultrasound theoretical research, different ultrasound imaging methods have been continuously proposed, improved, and commercialized, and until today, there are still an endless stream of new ultrasound imaging methods available.
The average propagation velocity of ultrasound in human soft tissues is 1540m/s, a value that every sonographer is familiar with. But, do you know who measured this value first? George Döring Ludwig (George Döring Ludwig) was the first to measure the average propagation speed of ultrasound in human soft tissues. This value has been used to this day.
