December 1, 2008
By Beth W. Orenstein
Vol. 9 No. 24 P. 28
Joan Baker delivers the McLaughlin Lecture at the 2008 SDMS Conference.
Manufacturers now make ultrasound equipment that is so compact, it can be carried to patients on battlefields or used by astronauts in space.
But it wasn’t always that way, noted Joan Baker, MSR, RDMS, RDCS, FSDMS, who was introduced at this year’s annual Society of Diagnostic Medical Sonography (SDMS) conference as its “matriarch.” Baker delivered the third annual Stephen McLaughlin Memorial Lecture at the conference held in mid-October, with more than 1,400 sonographers attending. McLaughlin, a former SDMS president, died in January 2005 from brain cancer.
Baker, who is president of Sound Ergonomics in Kenmore, Wash., spoke about the evolution of sonography and how it developed from a few pioneers to a profession with tens of thousands of practitioners.
It may have become cliché to say that “you do not know where you are going until you know where you have been,” Baker said, “but we witness so many times how history repeats itself. If we are to learn anything from our mistakes, we need to study our roots.”
The roots of sonography can be traced as far back as the ancient Greeks, according to Baker. Pythagoras, famous for his theorem about right-angled triangles, invented the Sonometer, which was used to study musical sounds. Boethius (c. 480-c. 525) was the first to compare sound waves to waves produced by dropping a pebble into calm water.
Most consider French physicist Pierre Curie’s discovery of piezoelectricity in 1877 to be the moment that ultrasound was conceived, Baker said. Thirty-five years later, sonographic imaging was developed by French professor and physicist Paul Langevin.
The desire to see inside the body drove many scientists through the late 19th and 20th centuries to develop probes and scopes for diagnosis and treatment. William Conrad Roentgen’s discovery of x-rays in 1895 is just one example, Baker said. Interestingly, the sinking of the Titanic on its maiden voyage in 1912 made people want to know how to detect submerged objects, she explained.
“Constantin Chilowsky came up with the idea for an ultrasonic detection system that he brought to the attention of the French government. The French government turned this over to Paul Langevin, one of the Curie brothers’ first students,” Baker said.
Ultrasound is no different from many other technological advances in that it owes its development to war, Baker said. “The French government called upon Langevin to develop a device capable of detecting submerged enemy submarines during the first World War. The device he developed used the piezoelectric effect that he had learned as a student of the Curies.”
The device that Langevin developed in 1917 was not completed in time to be applied to the war effort. “However, it did form the basis of sonar detection, which was developed during the second World War,” she explained.
A number of other scientists around the world made use of ultrasound technology. For example, in 1928, Soviet physicist Sergei Sokolov suggested using ultrasonic energy for industrial purposes, including the detection of flaws in metals.
But sonography as a medical diagnostic modality is relatively new, according to Baker. In the 1920s and 1930s, ultrasound was used for physical therapy, primarily for members of Europe’s soccer teams. “It also was used for sterilization of vaccines and for cancer therapy in combination with radiation therapy,” she said.
In the 1940s, ultrasound was seen as a cure-all. It was used for everything from arthritic pains to gastric ulcers and eczema.
Karl Dussik, a neurologist and a psychiatrist at the University of Vienna in Austria, is generally regarded as the first physician to employ ultrasound in medical diagnosis. Baker said that in the 1940s, Dussik and his brother, Freiderich, also a physicist, attempted to locate brain tumors and cerebral ventricles by measuring the transmission of the ultrasound beam through the skull. “They called their procedure hyperphonography,” she explained.
In the late 1940s, George Ludwig, while serving at the Naval Medical Research Institute in Maryland, used ultrasound to detect gallstones.
Other ultrasound pioneers include Douglas Howry, a University of Colorado radiologist who, in 1948, concentrated on the development of B-mode equipment that compared cross-sectional anatomy to gross pathology. Howry was one of few radiologists in the field of ultrasound, and he did his work in the basement of his home. “Every field can claim at least one famous basement/garage pioneer,” she said. “Using 2.5 megahertz, he produced a pulse-echo ultrasonic scanner in 1949.”
Some other unsung heroes of ultrasound include John Reid and John Wild who, in 1950, built a linear, handheld, B-mode instrument for breast tumors, and Joseph Holmes, who, in 1951, along with Howry and other engineers, produced the first 2D B-mode linear compound scanner.
“It was Wild’s hope to design a mass screening procedure for breast,” Baker said. “He continued to try to do this until 1960 when his lab was closed for administrative reasons, which later became the subject of a lawsuit.”
Another pioneer was Gil Baum, MD, who became involved in ultrasound in the early 1950s. “Dr. Baum was a special friend of mine,” she said. “He was president of the American Institute of Ultrasound in Medicine [AIUM] when I needed help with the manpower division of the American Medical Association [AMA] to create the occupation of sonographer. He helped me immensely because in those days, a nonphysician was not welcome in the hallowed halls of the AMA.”
Wolf D. Keidel was the first to use ultrasound on the heart, and Inge Edler and Hellmuth Hertz of Sweden are considered the “fathers” of echocardiography. Hertz was a physicist at the University of Lund in Sweden when he accidentally met Edler, a cardiologist, over lunch in early 1953. Their chance encounter was the beginning of a relationship that millions have benefited from, she said.
In 1956, Robert Rushmer, a U.S. pediatrician turned cardiovascular physiologist/bioengineer, brought two young engineers, Dean Franklin and Don Baker (Joan Baker’s husband), together to design instruments that could be used to characterize the cardiovascular system in dogs that were not put under anesthesia. “This led to the development of continuous wave Doppler as a handheld device,” Baker said.
1970s Sonic Boom
The late 1960s and early 1970s were referred to as the sonic boom, according to Baker. During this period, 2D echo was introduced by Klaus Bom. In 1966, Don Baker, Dennis Watkins, and John Reid developed pulsed Doppler, which enabled the detection of blood flow from different depths in the heart. Don Baker also was a member of the engineering team that later developed color Doppler and duplex scanning.
Real-time ultrasound started to appear in the early 1980s. With this development, “Ultrasound became more believable because those not used to using it could recognize what they were looking at,” Baker said.
In the 1990s, the field went one step further with 3D and even 4D images that the public could interpret. “This made ultrasound more difficult again, as we find ourselves discussing with the patient what we are looking at,” Baker noted.
In the early days, scanning equipment was very large. The first B scanner Baker operated filled a room 12 feet by 12 feet, she said. “It was the invention of the transistor and finally integrated circuitry that made it possible to build smaller and smaller equipment.”
Poor image quality slowed the acceptance of ultrasound, Baker noted, but in the 1980s, probes became smaller and image resolution improved significantly. Today, she said, the equipment is so compact, it can easily be carried and used in space and on the battlefield.
Transducer technology also has improved greatly over the years, Baker said. Original transducers had large scan heads and heavy cables. Ironically, “The return of the larger scan head and heavy cables is needed for 3D and 4D,” she said. Baker also addressed the history of both the AIUM and the SDMS.
Originally, the AIUM was run by a commercial company that held annual meetings to promote its equipment. “Gradually, over a five-year span there were fewer and fewer therapeutic members and more and more takeover from diagnostic ultrasound. When I attended my first AIUM meeting, there were still board members who were physiatrists,” Baker said.
In 1969, six nonphysicians and nonengineers attended the AIUM meeting in Winnipeg, Canada. L. E. Schnitzer and Baker went to the board of the AIUM to ask permission to form a society for technical specialists. “I had been doing ultrasound for almost 10 years and found it professionally lonely,” she said.
While the AIUM approved their request, Schnitzer and Baker were told that they were wasting their time because their efforts were premature.
Starting at Stanford
A native of England, Baker had been working at the Hospital for Nervous Diseases in London and was invited to Stanford Medical Center in Palo Alto, Calif., in February 1965 to open an ultrasound department.
In 1970, the American Society of Ultrasound Technical Specialists (ASUTS) was formed, with its official beginning at the AIUM meeting in Cleveland. The ASUTS became the Society of Diagnostic Medical Sonographers and then the Society of Diagnostic Medical Sonography, to incorporate all who are part of the organization.
In 1975, a doctor affectionately referred to the ASUTS as ASS-UTS. “That was all it took for all sonographers to be committed to change the name before it stuck,” Baker said with a laugh.
A key moment in the history of sonography came in 1973 when the occupation of sonographer was created through the U.S. Office of Education, according to Baker. Baker represented the ASUTS and the profession and fought hard for the occupation’s recognition.
Once sonography was a recognized occupation, its educational requirements needed to be defined. “In 1974, a committee was formed to write the Document of Essentials,” Baker said. “It took five years to get an agreement.” The Joint Review Committee on Education in Diagnostic Medical Sonography was founded in 1979.
Over the years, SDMS membership has grown exponentially, reaching more than 20,000 in August 2007, Baker said.
SDMS members and staff have been working for passage of the Care Bill in Washington, D.C., which would require sonographers to be credentialed. It is an important issue, she added, “and I hope that those we elect will have the wisdom to pass it. This legislation will protect the public and require standards for our profession.”
The SDMS also has worked with the Occupational Safety & Health Administration to help reduce work-related musculoskeletal injuries to which sonographers are prone, said Baker.
— Beth W. Orenstein is a freelance medical writer and a regular contributor to Radiology Today. She writes from her home in Northampton, Pa.