Radiation has been used in medical diagnosis and treatment throughout the century. But it was not until NIST became involved in providing physical measurement standards for radiation that this tool could be relied on to do more good than harm.
Early in the century, technicians operated X-ray equipment empirically—and without lead shielding—at somewhat arbitrary voltages. The need for standard dosages became clear after World War I, with wider use of more powerful X-ray apparatus for cancer therapy and frequent injuries to equipment operators. There also was concern about radium, a radioactive element used in surgery and dermatology that began appearing in consumer products.
In 1926, the Radiological Society of North America asked NIST to determine national standards for radium and X-rays used in diagnostic and therapeutic procedures. The Institute developed the new standard for X-ray exposure, which could be measured precisely, and produced the first quantitative data on X-ray doses in this country. Working through a national committee, NIST helped bring about the 1931 X-ray safety code, which set guidelines for the shielding of operating rooms and high-voltage equipment and for protective devices for patients and operators.
Radiation measurement work continues today. In the 1970s, NIST set up a program to assure accurate doses of radioactively tagged drugs used to diagnose or treat disease. The program tightened the system for measuring dosages and, according to an economic analysis, has a benefit-to-cost ratio of 97 to 1. NIST currently provides national standards for the 11,000 U.S. mammography facilities and is the only laboratory in the world offering an advanced calibration service—based on a radiation detector 100 times more sensitive than the previous one—for checking the radiation dose in seeds used to treat prostate cancer.
Within a few years of its founding, NIST purchased a hydrogen liquefier and began research on cryogenics, a branch of physics dealing with the production and effects of very low temperatures. Over the century, this research has contributed to scientific, military, aerospace, industrial, and medical fields.
First, the Institute devised a standard method of producing liquid and solid hydrogen at a temperature of about –259 OC (–434 OF), not far above absolute zero. In 1931, using the same apparatus, NIST produced America's first liquefied helium (the coolant used decades later in magnetic resonance imaging, or MRI). By mid-century, NIST was established as the federal expert on cryogenic engineering and published the classic book on the subject.
In the 1950s, NIST designed and constructed the world's largest hydrogen liquefier for the Atomic Energy Commission's nuclear fusion devices. The liquefier provided liquid fuel for the first hydrogen bomb, which was tested successfully. The Institute also began providing data and models to the National Aeronautics and Space Administration (NASA), which wanted liquid hydrogen for use as missile and satellite fuel. For the University of California at Berkeley, NIST helped construct a liquid hydrogen "bubble chamber" (see photo above)—the largest ever at the time—later used in Nobel Prize-winning research by physicist Luis Alvarez .
To meet the needs of industry, NIST gathered data on other cryogenic fluids used in steel and glass manufacturing, freezing of food, and other processes. Institute research on cryogenic refrigerators led to commercialization of this technology, which is used in NASA and Air Force satellites. In addition, NIST research on critical currents in superconductors has contributed to the design of superconducting magnets used in MRI systems and other applications.
For about two decades, NIST was the principal U.S. crime laboratory. The investigations were led by Wilmer Souder, a scientist who became interested in crime detection in about 1913. By the early 1930s, he was participating in 50 to 75 federal investigations annually involving extortion, kidnapping, forgery, and other crimes.
His most famous case was the kidnapping of aviator Charles Lindbergh's baby in 1932. Souder was one of several handwriting experts who independently identified the ransom notes as having been written by Bruno Richard Hauptmann, who after his conviction in 1935 reportedly said: "Dot handwriting was the worstest thing against me."
When the Federal Bureau of Investigation (FBI) hired its first scientist in 1932, Souder helped establish the new crime lab and lectured the trainees on various investigative techniques. When he retired from NIST in 1954, The Washington Post called him "one of the nation's best but ... least known criminologists."
NIST continues to assist law enforcement agencies. More than a dozen law enforcement standards have been issued since the early 1970s. One of them, a standard for ballistic resistance of police body armor, is used by companies that sell bullet-resistant armor to police and the military worldwide. Not a single police officer wearing body armor made to these specifications has been killed by penetration or blunt trauma.
NIST also has worked with the FBI for more than 30 years to improve fingerprint screening. After helping to design the first hardware for that purpose, in 1995 NIST created the first successful computer program that automatically classifies about 80 of 100 fingerprints into five categories. In addition, Institute researchers wrote standards for the exchange of fingerprint data among agencies, enabling real-time electronic distribution of images and information that has accelerated judicial processes.
To help out the Weather Bureau and Navy, NIST built a radiosonde, a balloon-borne instrument that greatly increased the range and quantity of available weather data. Effective up to heights of 24 kilometers (15 miles) or more and distances up to 322 kilometers (200 miles), the radiosonde transmitted continuous data on cloud height and thickness, temperature, pressure, and other phenomena. By 1940, it was an integral part of U.S. weather forecasting, and some 35,000 units were being built each year. In 1938, NIST developed a device that made possible, for the first time, accurate measurements of humidity. Radiosondes still are used today.
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