Concepts familiar from grade-school algebra have broad ramifications in computer science.
Dr. Robley D. Evans, professor emeritus of physics, winner of the 1990 Enrico Fermi Award and a pioneer in studying the effects of radium on the human body, died of respiratory failure on December 31 in Paradise Valley, AZ, where he lived in retirement. He was 88.
Professor Evans was a founder of the field of nuclear medicine and established the standard, used throughout the world, for the maximum permissible body burden of radium.
In its citation accompanying the Fermi Award, the Department of Energy said that Professor Evans did pioneering work "in measurements of body burdens of radioactivity and their effects on human health, and in the use of radioactive isotopes for medical purposes." The Fermi Award is the highest scientific award given by the DOE.
The DOE added that Professor Evans, as a founder of nuclear medicine, "occupies a special place in the history of radiation physics and biology and the development of our understanding of radiation effects today. He has had a unique impact on radiation biology."
As a graduate student at the California Institute of Technology under Nobel laureate Robert A. Millikan in the late 1920s, Professor Evans measured background radiation coming from the earth, so that it could be distinguished from cosmic radiation.
With this experience, his attention was drawn to the victims of radium poisoning, a national scandal in the 1920s. The painters of luminous watch dials in factories often used their lips to point their brushes and thus ingested radium. Radium had also been used indiscriminately in tonics and other medical applications in the belief that it was close to a cure-all and it had been handled carelessly by people in industry. Once in the body, it usually became concentrated in the bones, continuing to emit potentially dangerous radiation and often causing cancer or creating a skeletal condition that resulted in spontaneous fractures.
Professor Evans began his studies of the biological effects of radiation while he was a postdoctoral fellow at the University of California at Berkeley. After joining the MIT faculty in 1934, he established the Radioactivity Center and developed the meter arc method of measuring the amount of radium in the body as indicated by gamma radiation-a method still considered the most reliable and often referred to as the "Evans method."
This research led Professor Evans in 1941 to establish one ten-millionth of a gram of radium as the "maximum permissible body burden"-the greatest quantity of a radioactive substance that the human body can tolerate without a likelihood of damage, allowing a large margin for safety.
Establishing such a standard was crucial as the United States embarked on its atomic bomb program, in which large numbers of researchers and workers would be encountering radioactive materials. The standard is still used today.
The Radioactivity Center also produced the first iodine isotope for a number of medical purposes. With Dr. James Howard Means of Harvard Medical School, Professor Evans began to explore the use of radioactive iodine for the diagnosis and treatment of goiter.
Since iodine taken orally rapidly moves to the thyroid glands, "radioactive cocktails" containing an iodine isotope enabled physicians to study the metabolism of the glands by measuring the radioactivity with a Geiger-Muller counter. Radioactive iodine also proved effective in the treatment of hyperthyroidism.
Professor Evans's accomplishments in medical physics included development of a technique to preserve human whole blood, research primarily undertaken for the benefit of wounded servicemen in World War II. By using as many as two radioactive forms of iron and one of iodine-a so-called "triple tracer" experiment-doctors could determine how well transfused blood cells remained in a recipient's blood stream. A chemical was found to preserve the blood for up to three weeks, the time it required to reach distant battlefields and subsequently was used in blood banks for several decades.
Professor Evans' book, The Atomic Nucleus, was a basic text for graduate students in nuclear physics. First published in 1955, the book has been reprinted and revised and is still frequently cited.
In 1938, Professor Evans was responsible for MIT's first "atom-smasher," the first cyclotron in the world for biological and medical use. The cyclotron was also used in fundamental nuclear and industrial research and remained in service for some three decades.
The Radioactivity Center was involved with fundamental nuclear physics as well as medical applications. Examples of the work that was done include studies on the properties of nuclei; the development of instrumentation and methods for measuring radionuclides; standardization of radionuclides; development of radiochemical methods for isolating radionuclides, and development of methods of calculating radiation dose.
Professor Evans was born on May 18, 1907, in University Place, NE. At the California Institute of Technology, he received the BS degree in physics in 1928, the MS in 1929 and the PhD in 1932. He was an active member of the faculty for 38 years, retiring in 1972, after which he continued to visit MIT as a consultant and served as a special project associate at the Mayo Clinic in Rochester, MN.
A former colleague, Dr. Constantine J. Maletskos of Gloucester, MA, described Professor Evans as "a world-class physicist with an. uncanny ability to see through a problem, to simplify it and get at the important roots, and to set up an appropriate model for a seemingly simple solution to a complex analysis. His famous admonition in one of his radon papers, `A little contemplation saves a lot of calculation,' expresses it all."
Professor Evans also was regarded as a superb teacher, and many of the leading nuclear physicists today were among his 1,200 graduate students, 100 of whom completed their theses under his direction. He wrote a practical manual on teaching, "You and Your Students," which proved so useful to professors that it has been translated into several languages. More than 100,000 copies have been distributed throughout the world.
Among his many honors, Professor Evans was the recipient of the Theobald Smith Medal and Award in the Medical Sciences from the American Association for the Advancement of Science, the Presidential Certificate of Merit, the Hull Award and Gold Medal from the American Medical Association, The Silvanus Thompson Medal from the British Institute of Radiology, the Distinguished Achievement Award from the Health Physics Society and the William D. Coolidge Award from the American Association of Physicists in Medicine.
He was a member of many societies and professional organizations, and served as president of both the Radiation Research Society and the Health Physics Society. Among his memberships were the American Academy of Arts and Sciences (Life Fellow), the American Association for the Advancement of Science (Fellow), the American Association of Physicists in Medicine, the American Association of Physics Teachers, the American Industrial Hygiene Association, the American Nuclear Society, the American Roentgen Ray Society and the Royal Scientific and Literary Society of Sweden.
Survivors include his wife, Mary Margaret (Shanahan) of Paradise Valley, AZ, and three children from his first marriage, Richard O. Evans of West Palm Beach, FL, Ronald A. Evans of Tuscon, AZ and Mrs. Gene (Nadia) Hill of Corpus Christi, TX.