Guide to the Robert Ledley Papers
Digitized Content

Summary
Collection ID:
NMAH.AC.1135
Creators:
Ledley, Robert S.
National Biomedical Research Foundation. Georgetown University
Dates:
1972-1990
Languages:
English
Physical Description:
3 Cubic feet
Repository:
The Robert Ledley Papers document the development of the first whole-body diagnostic imaging system, the Automatic Computerized Transverse Axial (ACTA) X-ray Scanner by Ledley in 1973. Also included is material relating to Ledley's company, Digital Science Information Corporation (DISCO), as well as the public and medical communities' reactions to the scanner.

Scope and Contents
Scope and Contents
The Robert Ledley Papers document the development of the Automatic Computerized Transverse Axial (ACTA) X-ray Scanner, Ledley's company Digital Science Information Corporation (DISCO), as well as the public and medical communities' reactions to the scanner. The collection is arranged into nine series.
Series 1, ACTA Scanner I Schematics, 1973-1975; Series 2, ACTA Scanner I [Computer and Electronics], 1973; and Series 3, ACTA Scanner Tomograph Mechanics, 1973-1974 document the development and design of the ACTA scanner through drawings, notes, memoranda, and product information. More detailed information about these materials is located in the control file. All oversize drawings have been moved to flat storage for preservation concerns.
Series 4, ACTA Scanner Operating Instructions, 1975, is the operating manual created for the scanner used in Ledley's Georgetown lab.
Series 5, ACTA Articles, Clippings, and Press Releases, 1973-1979, is comprised of the aforementioned materials relating to the ACTA Scanner. Newspaper clippings illuminate the public's perception of the scanner, and scientific pieces highlight the medical community's reaction. Ledley's published articles on the scanner and related topics are included.
Series 6, Digital Information Science Corporation (DISCO) material, 1973-1981, documents Ledley's career and his company. A biographical sketch, list of articles, textbooks, and patents highlight Ledley's achievements. Invoices, receipts, contracts, and correspondence illuminate the financial situation at DISCO and the relationship between the company and Pfizer.
Series 7, Computer manuals, 1972-1975, documents the computer systems and software that were used with the ACTA Scanner.
Series 8, Photographic material, 1973-1978, includes an album of photographs depicting the ACTA Scanner and images of the scans it created. This album was disassembled due to preservation concerns. This series also includes a collection of slides featuring the scanner and related equipment in use and images of the scans it created. A detailed description of each photograph and slide is included in the control file.
Series 9, ACTA Scanner film, [1974?], is a 16mm narrated film describing the creation of the scanner, its components, the way they work, the scanner in use, and images of the scans produced.

Arrangement
Arrangement
This collection is arranged into nine series.
Series 1, ACTA Scanner I Schematics, 1973-1975
Series 2, ACTA Scanner I [Computer and Electronics], 1973
Series 3, ACTA Scanner Tomograph Mechanics, 1973-1974
Series 4, ACTA Scanner Operating Instructions, 1975
Series 5, ACTA Articles, Clippings, and Press Releases, 1973-1979
Series 6, Digital Information Science Corporation (DISCO) material, 1973-1981, undated
Series 7, Computer manuals, 1972-1975
Series 8, Photographic material 1973-1978
Subseries 1, Photographs, 19731978
Subseries 2, Slides, 1974
Series 9, ACTA Scanner film [1974?]

Biographical / Historical
Biographical / Historical
Robert Steven Ledley was born in Flushing Meadows, New York in 1926. He received a D.D.S. degree from New York University College in 1948. While attending dental school, he simultaneously studied at Columbia University; he earned a M.A. in Theoretical Physics in 1949. He volunteered for the army and was sent to the U.S. Army Medical Field Service School in Fort Sam Houston, Texas.1 After completing his service, Ledley held a wide variety of research and academic positions in physics, electrical engineering, and medicine.
Ledley was a physicist within the External Control Group of the Electronic Computer Laboratory of the National Bureau of Standards from 1953-1954. He was an operations research analyst within the Strategic Division of the Operations Research Office at Johns Hopkins University from 1954-1956. Ledley went on to become an associate professor in the Department of Electrical Engineering at The George Washington University from 1956-1960 while also serving as a consultant mathematician at the National Bureau of Standards Data Processing Systems Division, 1957-1960. At this time, Ledley also worked part time at the National Research Council's National Academy of Sciences from 1957-1961. Ledley became the president of the National Biomedical Research Foundation in 1960, a position he still holds today. He was an instructor of pediatrics at the Johns Hopkins University School of Medicine from 1960-1963. He returned to The George Washington University's Department of Electrical Engineering in 1968 where he was a professor until 1970. He then became a professor in the Department of Physiology and Biophysics at the Georgetown University School of Medicine in 1970. In 1974, Ledley also became a professor in the Radiology Department at the Georgetown University Medical Center. In 1975, he became the director of the Medical Computing and Biophysics Division at Georgetown University Medical Center.
In 1972, the British company Electric and Musical Industries Limited (EMI) released a medical imaging machine for use on smaller areas of the body that were positioned under a water tank. In 1973, Ledley developed the Automatic Computerized Transverse Axial (ACTA) X-ray Scanner (US Patent #3,922,552). This machine was a whole-body diagnostic medical imaging system. He was awarded a grant from the National Institutes of Health for an engineering equipment project, but the money was never received due to budget cuts. Ledley looked elsewhere for funding. He consulted with Georgetown staff and discovered a neurosurgeon had asked to buy a head scanning machine from EMI. Ledley did not think the images in EMI's brochure appeared clear, and he offered to create a similar machine for half the price. Georgetown agreed to fund this project for $250,000. Ledley secured the services of a machinist at a local machine shop, an electronic engineer, and a programmer/mathematician to assist in the project.2 The ACTA Scanner debuted in February, 1974 and did not require the use of a water tank.
Following the creation of the ACTA Scanner, Ledley organized Digital Information Science Corporation (DISCO) in order to manufacture the system. DISCO began producing scanners as orders were received. Due to financial constraints, DISCO was forced to request $100,000 upon receipt of the order, $100,000 when the scanner was halfway completed, and the final $100,000 payment upon delivery3. In 1975, Pfizer purchased the rights to manufacture the ACTA Scanner from DISCO for $1.5 million.
Ledley is a Fellow of the American Association for the Advancement of Science and a senior member of the Institute of Electrical and Electronics Engineers. He has earned numerous awards and honors for his work. In 1997, he received the National Medal of Technology from President William Jefferson Clinton for his pioneering work on the whole-body CT diagnostic X-ray scanner. He also founded the Pattern Recognition Society and Computerized Tomography Society.
Sources
1 Ash, J., D. Sittig, and R. Ledley. "The Story Behind the Development of the First Whole-body Computerized Tomography Scanner as Told by Robert S. Ledley." Journal of the American Medical Informatics Association, 2006 Sep-Oct (2006), 465-469, http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1561796. (accessed June 24, 2009).
2 Ibid.
3 Ibid.

Administration
Processing Information
Processed by Elizabeth Garber (intern), June 2009; supervised by Alison Oswald, archivist.
Separated Materials
An ACTA Scanner and numerous accessories were donated to the Museum in 1984.
Author
Elizabeth Garber.
Immediate Source of Acquisition
This collection was donated by Robert S. Ledley on September 18, 1984.

Using the Collection
Conditions Governing Use
Collection items available for reproduction, but the Archives Center makes no guarantees concerning intellectual property rights. Archives Center cost-recovery and use fees may apply when requesting reproductions.
Conditions Governing Access
The collection is open for research.
Preferred Citation
Robert Ledley Papers, 1972-1984, Archives Center, National Museum of American History, Smithsonian Institution

Custodial History
Custodial History
The papers were transferred to the Archives Center in 2008 from the Division of Medicine and Science.

Keywords
Keywords table of terms and types.
Keyword Terms Keyword Types
Medical innovations Topic Search Smithsonian Collections Search ArchiveGrid
Manuals -- 1970-1990 Type Search Smithsonian Collections Search ArchiveGrid
Patents Type Search Smithsonian Collections Search ArchiveGrid
Inventors Topic Search Smithsonian Collections Search ArchiveGrid
Inventions -- 20th century Topic Search Smithsonian Collections Search ArchiveGrid
Photographs Type Search Smithsonian Collections Search ArchiveGrid
Design drawings Type Search Smithsonian Collections Search ArchiveGrid
Correspondence -- 20th century Type Search Smithsonian Collections Search ArchiveGrid
Biology Topic Search Smithsonian Collections Search ArchiveGrid
Articles -- 20th century Type Search Smithsonian Collections Search ArchiveGrid
History of science and technology Topic Search Smithsonian Collections Search ArchiveGrid
Digital Information Science Corporation Topic Search Smithsonian Collections Search ArchiveGrid
Diagrams Type Search Smithsonian Collections Search ArchiveGrid
Diagnostic imaging Topic Search Smithsonian Collections Search ArchiveGrid
Slides (photographs) -- 1950-2000 Type Search Smithsonian Collections Search ArchiveGrid
Notes Type Search Smithsonian Collections Search ArchiveGrid
Motion pictures (visual works) -- 20th century Type Search Smithsonian Collections Search ArchiveGrid
Medicine Topic Search Smithsonian Collections Search ArchiveGrid
Medical technology Topic Search Smithsonian Collections Search ArchiveGrid
Medical radiology Topic Search Smithsonian Collections Search ArchiveGrid
Albums Type Search Smithsonian Collections Search ArchiveGrid
Whole body imaging Topic Search Smithsonian Collections Search ArchiveGrid
Tomography Topic Search Smithsonian Collections Search ArchiveGrid
Radiology Topic Search Smithsonian Collections Search ArchiveGrid
Computer-Assisted Tomography Scanner Corporate Name Search Smithsonian Collections Search ArchiveGrid
National Biomedical Research Foundation. Georgetown University Corporate Name Search Smithsonian Collections Search ArchiveGrid
Automatic Computerized Transverse Axial Scanner Corporate Name Search Smithsonian Collections Search ArchiveGrid

Repository Contact
Archives Center, National Museum of American History
P.O. Box 37012
Suite 1100, MRC 601
Washington, D.C. 20013-7012
archivescenter@si.edu
http://americanhistory.si.edu/archives