Radiology the History of Ultrasound

Radiology

The History of Ultrasound Technology

The history of ultrasound technology is a long and interesting one. It seems counterintuitive to learn that the technology we have today to diagnose life-threatening diseases as well as to diagnose prenatal issues, and to help maintain healthy pregnancies owes much of its development to wartime technology. Of course, many of our life-saving equipment in the medical and other fields seem to come from this ironic source. The technology has survived some precarious beginning as well as some disappointing stops and starts, but it has developed into a useful diagnostic tool that can not only find the smallest of abnormalities to help increase the chance of survival of many diseases, but can also be used to bring much relief and joy into the lives of expectant couples.

Ultrasound is a medical technology that is used to diagnose various diseases and other disorders, as well as contribute to a healthy pregnancy, or diagnose fetal abnormalities. It uses high-frequency waves to develop a visual representation of its subject from the echoes of these waves. Much like SONAR technology, the machine emits a an extremely high frequency pulse that enters the body and is reflected back to the receiver. The waves are measured as to the time and distance it took for them to reach the object and then bounce back to the receiver. This measurement is then calculated by the machine and what is produced is a two-dimensional picture of the objects being examined (Howstuffworks.com). Though so far not used for medical or diagnostic purposes, the technology has been developed even further to be able to produce three-dimensional pictures of the object. Right now this advanced technology is used for recreational purposes for expectant parents to see the facial features of their unborn children. This can also be used for a four dimensional video session as well. This newest advance is slighty controversial, however, because many medical professionals feel that there could be some side effects not yet discovered from this process, and they often prefer subjecting a fetus to the ultrasound process as few times as possible throughout a normal pregnancy

Ultrasound technology's roots are in the development of SONAR technology in the mid-19th century. The concept of high-frequency sound waves, or "ultrasound," had been around since the late 18th century when an Italian scientist began exploring the natural navigational system used by bats. In 1876, Francis Galton developed the Galton whistle, which was capable of producing the high-frequency sounds, however, "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 1880" (Woo, 1). RADAR and radio technology developments during World War I also had a reasonable contribution to the early development of ultrasound.

At first, ultrasound technology was used not for diagnosis, but for therapy treatment. Just as with many budding technologies in the late 19th and early 20th centuries, ultrasound was appropriated for many misguided uses and its benefits were touted for just about every disease from arthritis to heart disease (Woo, 4). This broad and reckless use of the new technology became an obstacle to the development of ultrasound because of the inevitable complaints of damage from these "breakthrough" treatments, and so no major advances were made until the 1940s.

Very near the beginning of World War II, Karl Dussik began exploring ultrasound technology for diagnostic purposes by "attempted to locate brain tumors and the cerebral ventricles by measuring the transmission of ultrasound beam through the skull" (Woo 7). This experiment produced disappointing results, and the development of this apparatus was not pursued further because of the elaborate set-up, and lack of clear visual representations of the brain.

However, at about the same time in Hamburg, Germany, Heinrich Netheler and Wolf-Dieter Keidel were independently working on developing ultrasound technology for the purpose of diagnosis. Where most development on the topic was still focused on the treatment of diseases, both Keidel and Netheler presented papers to the First Congress of Ultrasound in Medicine held in Erlangen, Germany in May, 1948, on the potential of ultrasound technology use in the diagnostic field.

The first diagnostic research conducted in the United States was released as a report to the public in 1949. Though the research had been going on for quite some time, it was being explored under the supervision of the military by a young Lieutenant at the Navel Medical Research Institute by the name of George Ludwig. He conducted research on animal tissue that included such experiments as attempting to detect the presence of human gall stones that had been embedded into animal tissue.

Ludwig's efforts were integral to the advancement of ultrasound technology in the diagnostic arena.

Among other important original findings, Ludwig reported the velocity of sound transmission in animal soft tissues was determined to be between 1490 and 1610 meters per second, with a mean value of 1540 m/sec. This is a value that is still in use today. He also determined that the optimal scanning frequency of the ultrasound transducer was between 1 and 2.5 MHz. His team also showed that the speed of ultrasound and acoustic impedance values of high water-content tissues do not differ greatly from those of water, and that measurements from different directions did not contribute greatly to these parameters. (Woo 28)