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

This collection is arranged into nine series.

Subseries 1, Photographs, 19731978

Subseries 2, Slides, 1974

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.

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.