Michael E. Phelps, 1998


For his invention of Positron Emission Tomography (PET), and his seminal contributions to its use in research and patient care in neurological disorders, cardiovascular disease and cancer; and for the breadth of his accomplishments that combine physics, mathematics, chemistry, biology, and medical applications.


Michael Phelps is the scientist most often identified as the inventor of PET, a technique that permits the imaging of biological processes in the organ systems of living individuals. Phelps has advanced biomedical imaging by producing four generations of PET scanners, including the prototypes on which all of today's commercial PET scanning systems are based.

Following its inception in 1973, PET has been used in a wide variety of medical applications. For example, PET images of glucose metabolism provide pictures of the metabolic function of the living, developing or aging brain and heart muscle, as well as the altered metabolic states that occur in diseases such as Alzheimer's disease and cancer. PET technology has been applied to the early diagnosis and therapeutic responses in lung, colorectal, breast, ovarian, lymphoma, melanoma, and prostate cancers. PET imaging probes of neurotransmitters are used to observe the normal communication between neuronal systems in the brain as well as the alteration of neuronal functions in disease such as Parkinson's and drug abuse. Recently, Phelps and his co-workers developed an approach to imaging gene expression that promises to be an important contribution to the rapidly expanding field of molecular medicine.

Phelps' initial work dealt with the application of basic nuclear physics, chemistry, and mathematics to biomedical imaging. He combined a number of original insights in developing PET: First, he recognized that positron decay provides the opportunity for a unique coincidence detection system, with opposing detectors. This detection system allows spatial resolution previously not obtainable. Second, using the principle of coincidence detection, he configured a circumferential array of detectors and associated electronics and a mathematical algorithm for forming three-dimensional tomographic images of biological probes of the living human body. Finally, he recognized that the positron-emitting forms of oxygen, nitrogen, carbon and fluorine provide the tools to "label" biochemical molecules for their use as probes, to non-invasive image biological processes in living individuals. By 1973, Phelps was able to convert these insights into the first PET scanner.

Phelps subsequently developed an array of biological assay techniques for PET-based measurements of hemodynamic, biochemical, and biological processes in the brain, heart, and tumors. The success of these measurements drove further refinements both in the development of PET scanners and in the development of biological assay methods. Phelps also conceptualized the miniaturization, automation, and integration of cyclotron technology and biochemical synthesizers necessary for the synthesis of positron-labeled probes into a single, PC-controlled device for producing positron-labeled compounds for research and clinical care.

Phelps established and directed the first clinical PET service exclusively for patient care. This clinic was the first to be used for PET-based diagnoses in such areas as Alzheimer's disease, multi-infarct dementia, Huntington's disease, depression, Parkinson's disease, adult and childhood epilepsies, cardiovascular disease, and numerous types of cancers. Phelps established a large training program to produce scientists and physicians with expertise in PET scanning. His trainees now populate PET research and clinical centers throughout the world.

Michael E. Phelps was born in Cleveland, Ohio, in 1939. He earned his B.S. in Chemistry and Mathematics from Western Washington State University in 1965, and his Ph.D. in Chemistry from Washington University, St. Louis, in 1970. He began his faculty career at Washington University School of Medicine, 1970-1975. From 1975-1976, Phelps was a member of the faculty at the University of Pennsylvania, Philadelphia. In 1976, he moved to the University of California School of Medicine, where he has held the following positions: Professor of Radiological Sciences, 1976-1992; Professor of Biomathematics, 1980-present; Chief, Division of Biophysics, 1981-1984; Jennifer Jones Simon Professor, 1983-1996; Norton Simon Professor, 1996-present; Chief, Division of Nuclear Medicine, 1984-1992; Associate Director, UCLA/DOE Laboratory of Structural Biology & Molecular Medicine, and Chief, Division of Nuclear Medicine, 1984-present; Director, Crump Institute for Biological Imaging, 1989-present; and Chairman, Department of Molecular & Medical Pharmacology, 1992-present; and Chief, Division of Nuclear Medicine, Department of Molecular & Medical Pharmacology, 1992-present.

Phelps has received numerous awards, including George von Hevesy Foundation Prize, 1978, 1982; Certificate of Excellence, Society of Cerebral Blood Flow and Metabolism, 1979; Oldendorf Award, Society for Computerized Tomography and Neurological Imaging, 1981; S. Weir Mitchell Award, American Adacemy of Neurology, 1981; Paul Aebersold Award, Society of Nuclear Medicine, 1983; Ernest O. Lawrence Award, U.S. Department of Energy, 1984; Special Award for Individual Distinction, American Nuclear Society, 1984; Sarah L. Poiley Memorial Award, New York Academy of Sciences, 1984; Richard and Hinda Rosenthal Foundation Award, American College of Physicians, 1987; Landauer Memorial Award, American Association for Physicists in Medicine, 1988; Ted Block Memorial Award, Society of Nuclear Medicine, 1989; Robert J. and Claire Pasarow Foundation Award, 1992; and the Distinguished Scientists Award, Institute for Clinical PET, 1995. He is a member of the Institute of Medicine of the National Academy of Sciences.

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